Genesis of the Electrochemical Instrumentation at ... - ACS Publications

Waters Symposium: Electrochemistry edited by

Waters Symposium

Adrian C. Michael University of Pittsburgh Pittsburgh, PA 15260

Serendipity: Genesis of the Electrochemical Instrumentation at Princeton Applied Research Coorporation J. B. Flato J. B. Flato & Associates, Lafayette, CA 94549; [email protected]

Over the course of the 20th century, the capabilities of laboratory instrumentation grew from primitive spectrographs and simple balances to today’s incredible devices: ICP–MS systems, full-body scanners, among others. The names of the giants who invented these breakthrough instruments are wellknown to everyone: Beckman and his pH meter, the audio oscillator of Hewlett and Packard that started the field of electronic test equipment, Kirkland’s original work in pressurized liquid chromatography, and even Heyrovsky’s Nobel Prizewinning polarograph. These were scientific giants whose vision, initiative, and hard work gave rise to some of the most significant developments in the field. However, the creation of significant new instruments is not always a result of genius and vision. Sometimes, it arises from a combination of commercial or financial pressure and fortuitous circumstances. In the late 1960s, Princeton Applied Research Corporation (PAR) was a small electronic instrument company trying to expand out of its base in the physics laboratory. They were experts in electronic “signal-processing” technology and believed that there should be applications of these techniques in other areas of scientific research. At that time, the major analytical instrument companies were concentrating on newly emerging techniques such as atomic absorption and, shortly thereafter, liquid chromatography. They had little interest in electroanalytical techniques because they felt the market was too small. PAR was used to dealing with physicists who required minimal support from their instrumentation sources, but they believed that the advantages that would be derived from signal-processing could outweigh other considerations in allowing them to penetrate selective markets. In retrospect, the foray into electrochemistry succeeded in spite of itself. PAR entered the market appreciating neither its size nor the support requirements that chemists had, but its instrumentation was sufficiently useful and the applications sufficiently important as to create a substantial business. The timing was also particularly fortuitous. Many of the trace-metal determinations and exotic organic analyses that were the basis of PAR’s commercial success became much easier to perform using more sensitive and more foolproof, albeit far more expensive, techniques a decade or so later. Advanced HPLC, LC–MS, ICP, and other alphabet-soup measurements have supplanted polarography in most laboratories, although the research applications of electrochemical measurements are still important. Digital techniques and linked computers brought evermore complex measurements under control, and user-friendly control panels with real switches were replaced by color screens and keyboards. In its heyday, 656

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however, the PAR line of relatively inexpensive, user-friendly analog instruments were ubiquitous in university and industrial laboratories around the world and were familiar to an entire generation of lab workers. The story of the beginnings of electrochemistry at Princeton Applied Research Corporation is a perfect example of how good things sometimes take place orthogonally to the people involved, as a result of serendipity and plain dumb luck! Princeton Applied Research Corporation In the fall of 1966, a small company in Princeton, New Jersey ran an intriguing ad in the employment section of the Sunday New York Times. Only one column by 2 or 3 inches, the headline was “Instrumentation Scientists”. The body copy sought “Ph.D. Physicists, Chemists, Electrical Engineers, and Mechanical Engineers interested in developing new instrumentation”. Very little other information was provided (Figure 1). Princeton Applied Research Corporation (PAR) was founded in 1961 by three Princeton-area physicists. Thomas Coor had been working at the Princeton–Penn accelerator. His expertise was in applying electronic techniques to noisy signals to extract their information content. This was commonly called “signal processing”. Emil W. (Wendy) Lehmann had been one of the administrators at the accelerator. Orest C. (Chick) Chaykowsky joined them from another Princeton-area electronics company to function as head of sales and marketing. The company was founded with investments from several Princetonarea Wall Street types who served on the company’s board. They

Figure 1. New York Times recruitment ad.

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Waters Symposium: Electrochemistry

also invited Robert H. Dicke, a Princeton University physics professor who was one of the leading proponents of signal-processing techniques, to serve as a director. Shortly after start-up, PAR was joined by Harry S. Reichard, an electrical engineer who had also worked at the accelerator, who functioned as a circuit designer extraordinaire. In 1966, PAR had been in business for a number of years and was doing exceedingly well selling products such as lock-in amplifiers and boxcar integrators to physics researchers. They had built up a considerable stock of cash and equity and their Wall Street advisers told them to diversify. I responded to the New York Times ad and was invited for an interview. When I met with Tom and Harry they explained a little about their techniques for processing noisy signals in the physics lab. They believed that these techniques were equally applicable to other types of research—chemistry, for example—and were seeking scientists to develop instruments that would employ those techniques in their own fields. It sounded interesting to me, although I really had no idea what signal-processing was. After the usual sorts of negotiations, I accepted a position with the title of senior research chemist. I was not the only respondent to the New York Times ad. Over a short period of time, PAR also hired an EE who had previously worked at Perkin-Elmer in atomic absorption, a cryogenics engineer, a systems engineer, and a physician with a background in electronic circuitry. Each of us was told to go find new instruments for Tom, Harry, and company to design. We were given no guidance as to how to do this and left pretty much on our own. Tom Coor and Wendy Lehman had spent many years working in university physics research labs. In the academic environment, they had had the opportunity to learn about a cross-section of physicist’s needs and wants in instrumentation. This led them to develop a long mental list of products for the physics lab even before they started the company. They expected their newly hired staff of assorted instrumentation scientists to apply their familiarity with their own fields to do the same thing. The PAR people at the time held the view that physics was the ultimate science and that all other fields were simplifications and subsets of it. They felt sure that they could apply their superior knowledge of all things scientific to solving the “petty” problems of chemists, doctors, engineers, or whoever, as long as someone told them what the problems actually were. I remember one day, for example, that Tom Coor suggested that I visit Princeton Chemical Research, a company located up the street from us, to see what their problems were. His comment to me was “They have actual chemists over there making smells!” It turns out that PCR actually manufactured golf balls, and had nothing particularly useful for us. OK, So What Shall We Make? I was fresh out of grad school and way over my head. I had no idea how anyone would decide what products people might buy or how to go about finding this out. Unlike Tom, Wendy, and Harry, I had had only a few years of graduate study in which to interact with other chemists and learn about their needs. My previous sales experience had been limited www.JCE.DivCHED.org

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Figure 2. Block diagram of Diefenderfer ac polarograph (1).

to selling bands and orchestras to people about to get married, experience that did not really carry over. I was given an intensive but abbreviated course in signal-processing techniques, usually over lunch, and I tried to see how these techniques might be applied to chemistry research problems. The first application I looked at was in atomic absorption (AA) spectroscopy, a field that was growing explosively. Sensitivity was the most important parameter of AA instruments, and the sensitivity was strongly affected by the signal-to-noise ratio of the burners used to atomize the sample. Many people used PAR lock-in amplifiers to process AA signals, and the PAR people felt that this might be a potential market to address. We came up with a number of interesting variations on the basic AA technique involving the use of lock-ins, and I spent several months trying to get results better than the competition. I failed, which was probably fortunate since PAR never could have supported a competitive AA instrument line in the marketplace. Scratch one market! AC Polarography?? During this period of the late 1960s, every issue of Analytical Chemistry included at least half-a-dozen of what I call “triangle” articles. These were articles describing how an electrochemistry researcher had made some wonderful measurement using an instrument constructed from off-the-shelf operational amplifiers from companies like Philbrick and BurrBrown. Each article contained circuit diagrams filled with operational amplifiers, for which the circuit symbol was a triangle, leading to the designation. In grad school, I had built several such devices and had a passing familiarity with them. I had been looking at these articles and thinking about possible commercial opportunities when Tom Coor approached me one day with a article from the December 1967 Analytical Chemistry entitled “Alternating Current Polarograph with Simplified Phase Detection” by Ronald F. Evilia and A. James Diefenderfer (1). In this article, the authors built a triangle-based instrument to perform ac polarography with phase-sensitive detection, using a PAR lock-in amplifier as the detector (Figures 2


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Figure 4. “Universal” electrochemical instrument circuit configuration.

Figure 3. Circuit diagram of Diefenderfer polarograph (1).

and 3). Their results suggested that they could obtain significantly better sensitivity and resolution than other reported polarographic methods, including non-phase-sensitive ac polarography. Tom wondered whether a commercial ac polarograph incorporating this method could be of interest. Tom and I visited Diefenderfer, whose location at Lehigh University was only an hour or so from Princeton. His work seemed interesting, but I remembered the problems I had always encountered when trying to perform real polarographic analyses, using everything from an old Sargent dc unit to a “Polarotrace” cathode ray system. Diefenderfer’s classic triangle article demonstrated what a triangularly-competent researcher could accomplish. However, I was not sure that the commercial possibilities were worth pursuing. Nonetheless, it seemed clear that there were many scientists doing interesting electrochemical research using operational amplifiers. It also was suggested that many others would have liked to have done so but they were triangularly-challenged. I thus began to think about an instrument that incorporated not only ac polarography but various other electrochemical measurements, one that could be used by a scientist with no knowledge of operational amplifier circuitry. A Multifunctional Instrument I have never been sure whether it was my naiveté, their enthusiasm, or miscommunication, but I came away from my original PAR interview with the impression that I would learn what signal-processing meant, seek out chemistry applications for it, and then come up with specifications for the products. Tom, Harry, and their associates would then develop the products, with some degree of comment and review from me. Although I had designed and built various instruments in grad school and had a reasonable background in electronics and circuit design, I certainly was not qualified as a design engineer and had absolutely no concept of what went into a commercial product. In most businesses, market research is a fundamental tool employed to help define new products and evaluate their potential. At PAR, formal market research was unheard-of.

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There was an individual whose title was market-research manager, but his primary activity was to manage the distributor organization—his market research consisted of informal conversations with distributors and customers. Since PAR had no customers in electrochemistry, he was unable to provide any relevant information. My primary source of information in developing these product specs was Analytical Chemistry and the large number of triangle articles that appeared in each issue. Since there were few commercial instruments to look at and little information about what techniques were being most widely used, the only method we had to determine what types of measurements to include in an instrument was to count up the number of citations in the journals and use them as an indication of popularity. We were able to get some indications of what would and would not be viable, but more importantly, it soon became apparent that if one ignores the switching issues, virtually all of the publications employed the same basic circuitry, with only minor variations. This led to the conclusion that we could develop several different products using the same configuration, just by varying the complexity of the switching and perhaps the power parameters (Figure 4). Eventually, we settled on just two products—a polarograph to perform ac, dc, and perhaps some other forms of polarography, and a general-purpose device that could operate in many modes and perform a large number of different electrochemical techniques. The general-purpose instrument was designated the model 170, from an arcane system of model numbering PAR had developed to categorize products by market, and the ac polarograph was the model 171. I drew up a block diagram of an instrument, came up with some specifications for the various amplifiers, and submitted it to Tom Coor and Harry Reichard. My expectation was that they would assign an engineer to me and that together, we would convert my rough block diagram into detailed product designs, with me providing the chemistry input and an engineer doing the engineering. Reality, however, was a little different. All this was taking place in the summer and fall of 1967, and PAR was in the midst of a major expansion


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were still, however, a long way away from actual design specifications, and we still needed to solve a number of technical issues, such as whether potentiostatic circuitry was really needed and what to do about the pesky mercury drop and its unpredictable behavior.

Figure 5. Potentiostatic (three electrodes) versus simple potential (two electrodes) control.

program. Each of the new hires was trying to come up with a new product or product line and each wanted engineering assistance. At the same time, the signal-processing core of the company was engaged in a major redesign of the company’s flagship lock-in amplifier, the HR-8. This product line was the most important cash cow for the business, as well as the primary interest of its leaders, and thus got the highest priority. As a result, when I asked for engineering assistance, I got comments like “This is pretty simple stuff—can’t you just design it yourself ”, and “We’ll help you out where necessary” instead of staff members. I pleaded ignorance, lack of engineering experience, and general incompetence. Eventually, they agreed to assign one junior engineer to help me. Frank Eckert was a non-degreed engineer who had learned his circuit design in the army. Frank proved invaluable over the ten years or so we worked together. He was the essence of a practical engineer. I would come up with all sorts of far-out approaches to various problems. Frank would then remove the unnecessary components and add the critical bypass capacitors, protection diodes, and bleed resistors that turned a paper design into something that would actually work. Actual Measurements Between seminars on circuit design conducted by Harry Reichard over overdone hamburgers and lessons in practical circuit design and construction from Frank Eckert, we eventually managed to pull together breadboards of the amplifiers, hook them up to a purchased E. H. Sargent dropping mercury electrode (DME), and actually run some polarograms! I also managed to convince them to hire another chemist at that point, and Marty Hackman, who had worked with me at a previous job, was brought on board to serve as the bench chemist doing the actual measurements. Of course, we were not doing anything that had not been done elsewhere before, but we proved to ourselves that the circuitry would serve the function and perform the measurements. We were thus able to prove that we could run actual polarograms. We

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Potentiostat? For example, I had to justify the additional expense and effort that a potentiostatic system would entail. It had been well-established that applying the potential across the entire cell in an electrochemical measurement, rather than just across the working electrode–solution interface, led to errors that increased markedly in higher resistivity solutions or at higher potentials. Potentiostatic circuitry provided much more precise control of the applied potential at the working electrode– solution interface by using an actual reference electrode to monitor the potential at that point. The potential thus monitored was then fed back to the control amplifier so as to correct for any potential drops occurring between the amplifier’s output and the working electrode. Commercially available instruments at that time did not include potentiostatic control, probably because the cost of including such circuitry before operational amplifier technology became readily available was prohibitive. Using such circuitry required a “buffer” amplifier of high input impedance to prevent polarization of the reference electrode and a control amplifier of sufficient compliance to apply an “excess” potential at the counter electrode, which would result, after any potential drops in the system, in the correct potential being applied at the working electrode. Scientists had been performing electrochemical measurements for years before potentiostats became available, and one school of thought held that they did not make much difference. However, Figure 5 shows the same polarogram, run on the same solution, with and without potentiostatic control. This simple experiment on a simple solution proved that it was worth doing even in the simplest systems. The “Infernal” Dropping Mercury Electrode Heyrovsky’s original Nobel Prize-winning work used a dropping mercury electrode (DME) because it provided a continuously renewed, perfectly smooth electrode surface. Mercury also has other advantages. It has a high hydrogen overpotential and it gives rise to reversibility in many measurements because the ions are reduced at the electrode into metal atoms, which are actually soluble in mercury. Unfortunately, a DME is also a great nuisance, particularly if it is being used in measurements where other actions must be synchronized with the mercury drop in some way. The drop fall is not always reproducible, stray vibrations can dislodge it prematurely, and the rate of mercury flow, and thus the point in time at which the drop falls off of its own weight, varies with the applied potential. On the other hand, the technique called polarography was defined as the subset of voltammetry specifically performed at a dropping mercury electrode and it had always been the standard used. We felt that we had to start with a DME. Nice clean single-element polarograms, run in strong supporting electrolyte solutions containing few extraneous species and minimal contamination, give results like the ones


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Figure 6. Polarogram of 10᎑5 M chloramphenicol in 0.1 M acetate buffer.

Figure 7. Sampled, low-pass-filtered, and unprocessed polarograms of the identical solution.

in Figure 5, and one could conceive of their use in a practical analytical laboratory for actual analyses. However, few people need to continuously analyze cadmium and lead in water as their only activity for the rest of their lives. As soon as we tried to analyze more complex systems such as that in Figure 6, the smooth sigmoid curve turned into a wiggly line with indeterminate inflection points and was clearly not usable as a competitively attractive analytical technique. The conventional solution to smoothing the polarogram was to use a low-pass RC filter to damp out the oscillations produced by the growth and fall of the mercury drop. However, it was clear that using such a filter would distort the polarogram, particularly if the rate at which the excitation voltage was scanned was reasonably high. Schemes for mechanically dislodging the mercury drop or superimposing high-frequency signals to detect when the drop fell had been published. Today, we would not think twice about setting up a simple system with a laser diode and a detector to monitor the drop, but such devices did not exist at the time. Use of a mechanical drop dislodging device—a drop timer—seemed to be the simplest approach. It would have the added advantage of allowing the use of drop times much shorter than those that could be obtained from a natural drop fall. Using such a device also permitted us to sample the current at a predetermined point in the drop growth–fall cycle, and thus eliminate display of the large excursions produced by recording the entire cycle. Figure 7 illustrates the differences in shape between an unfiltered polarogram, one in which an RC filter was employed, and a sampled system. The sampled system reproduces the shape of the envelope precisely, while the filtered system produces a highly visible distortion even in the ideal case. Some of our advisors expressed concern about distortions that might be produced by the mechanical drop timer—effects of the sideways motion of the capillary or the drop, stirring of the solution, and so forth. Some relatively simple investigations satisfied us that these effects could be ignored. In Figure 8, we show oscilloscope photographs of two voltammograms taken in the same solution under identical conditions, except that one case is a naturally falling drop while the other is a mechanically timed drop. The differences between the shapes of the two traces, at least on the timescale employed, are imperceptible. Mechanically timed drops allowed us to know exactly when the current would reach a maximum on each drop. This allowed us to use sample-and-hold circuits to eliminate the effect of the drop fall on the output signal, producing the smooth curves, with envelopes that reproduced the maximum of the DME signal, which became characteristic of these instruments. Operational Amplifiers 101

Figure 8. (top) Mechanically timed drop and (bottom) naturally falling drop.

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One circuit of particular importance was the “electrometer” amplifier, a high input-impedance amplifier to buffer reference electrodes so that they could be fed back into the potentiostat summing amplifier (Figure 9). Before the development of such high input-impedance devices, using such electrodes was feasible only in a null-balance arrangement, where no current was drawn from the electrode. To have true


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Figure 9. Basic electrometer circuit. Figure 10. Programmer section of model 170 control panel.

potentiostatic control, however, it was necessary to come up with a circuit that allowed the reference electrode potential to be continuously monitored without polarizing the electrode, and this in turn required a buffer with impedance sufficiently high as to not draw any appreciable current. I fumbled with this design for a while, getting basically nowhere, until I brought it up one day at lunch in the local hamburger joint. Harry Reichard proceeded to sketch out a circuit for a MOSFET input amplifier on the back of a placemat. That circuit, virtually unchanged, was the basis of the reference electrode amplifiers in all the PAR electrochemistry products at least as long as I was there! This was the period before widespread use of integrated circuits and certainly before anything was digital. We were designing amplifiers using individual transistors and diodes. There were some packaged op amps available in the market place (the well-known Fairchild 709 for example) but we would have had to add additional input and output stages and assorted trimming networks to meet our needs. The PAR people were experts at amplifier design and felt it was better and cheaper to design our own amplifiers. In fact, while I did not get much support from engineering when I asked for staff, I got an incredible education in amplifier circuit design from Tom and Harry. They had a nonmathematical way of looking at circuits that allowed me to learn, in a matter of months, how to design the sorts of circuits we needed, how to oversee the circuit board layouts, and how to select the appropriate components. They had told me that this was pretty simple stuff when I asked for help, and indeed they made it so. In fact, the most complicated things in any of the PAR analog products, by far, were the rotary switching networks used to implement the various operating modes—the actual functional circuits were quite simple and elegant. www.JCE.DivCHED.org

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OK, What Does It Actually Do?? My original mandate had been to look into ac polarography, as prompted by the Diefenderfer article. My highly advanced, detailed market research, accomplished by browsing through Analytical Chemistry, suggested that there was more interest in various “sophisticated” techniques for electrochemistry research than there was in a polarograph, ac or otherwise. While there had been a great deal of data published by researchers using triangle systems, we needed to concern ourselves with the commercial potential of the instrument. We needed to determine which features would enhance the saleability of the product(s), and then we had to balance the implementation costs of each feature against the degree to which the sales potential would be enhanced. These tradeoffs are faced in every development project, but the difficulty was exacerbated by our lack of feedback from the actual marketplace. At this time, PAR had no presence in any field of chemistry, except perhaps for those spectroscopists who used lockin amplifiers in their home-brew instruments. There were no salesmen talking to chemists in the field and no chemists calling the company and asking for help. PAR management, coming from a strict academic background, did not believe in common market-research techniques—focus groups, market surveys, trade show interviews—and there was absolutely no interest in spending any money to employ them. We also were short of time, as it had been decided that the instrument would be introduced at the Pittsburgh Conference in March 1968, and we were, at that point, in the summer of 1967. Thus, for the research instrument, we used the kitchen sink approach. We put in every capability we could think of that could be achieved by reconfiguring the basic block diagram, from dc polarography to all sorts of pulsed voltage and


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Figure 12. Signal Processor control panel.

Figure 11. Measured Quantity control panel

current possibilities. We even built in a pH measurement function simply because we had the circuitry to do it. And How Does It Do It? Since this was long before the days of computers, the only way to make a rational user interface for such a system was essentially to allow (force) the user to invent the techniques themselves. The user would have the ability to separately select the excitation technique and the measurement technique and separately determine the individual parameters of each. Instead of having a function knob with a large collection of named techniques on it, we provided primitive programming capabilities for both the excitation end of the experiment and the actual measurement. Figure 10 shows the “Programmer” section of the instrument’s control panel. On the “excitation” side, the user could select voltage or current, ramped or pulsed, with various modulations. The starting and ending points of the scan could be selected as well as the modulation amplitudes. It is worth noting that, in an effort to provide precision, we used “digital” knobs operating 10-turn helical potentiometers to set the actual parameter values. Figure 11 shows the “Measured Quantity” control section. The instrument could be set to measure either potential or current in a variety of ways. A direct potential reading could be taken or the potential could be monitored while a constant current was applied. For more precise measurements, an actual null potential measurement could be made using a measurement philosophy derived from primitive nonelectronic measurement instrumentation. Similarly, the current could be plotted as a function of potential under a variety of conditions, including direct voltage scan, pulsed potential scans, “derivative” pulse, and even ac modulation using a built-in phase-sensitive detector. Subsequent to the raw measurement, we included a signal-processing section, pictured in Figure 12. Here, different modes of data presentation, including smoothed, integrated, and sampled, were provided. When used with a DME, the drop time could be varied. A phase-sensitive detector was included for ac polarography, our original start662


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ing point. By allowing the parameters of both the excitation and the measurement to be varied, model 170 gave researchers a level of flexibility in an analog instrument that was probably ahead of its time, although providing such functions with a modern computer-based system would be child’s play. By today’s standards, what we were doing was primitive from a design point of view, but incredibly laborious as to implementation. We also were working very fast, when viewed from 35 years in the future. I joined PAR in January of 1967. We settled on the basic concepts of the instrument in the summer of that year, and it was announced, with the usual sort of “hardware” article, at Pittcon in Cleveland in March 1968. The instrument showed at the conference was an advanced prototype but much of it worked. First production instruments were not shipped, however, until about a year later as we still had a great deal to learn about design for production and actually producing these products. That we got all this done quickly was especially amazing when it is realized that the staff involved was incredibly small—one junior engineer, one wireperson, one mechanical designer, and one draftsman—and that the group was under the direction of someone—me—who had absolutely no idea how to go about designing or specifying a manufacturable commercial product! Actual Product Development Process Some of the most interesting and memorable parts of the project came up during the manufacturing design period. The legerdemain that covers the transition from a laboratory breadboard to something you can ship around the world and keep working in remote locations is not usually exposed to the scientific community, so we will provide some anecdotal insight here.

Packaging An issue that comes up in the design of any instrument is packaging—not the shipping cartons, but the actual case in which the instrument is built. At the time of the 170 project, PAR had standards for instrument packages based on the concept that the products would be rack-mounted in


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Figure 13. Commercial 6-pole, 2-position wafer switch.

Figure 14. Blank switch wafer diagram.

a physics lab. All the instruments were in 19-in. wide rackmountable boxes whose height varied depending on the complexity of the product. There were no provisions for recorders or other output devices. PAR instruments, such as lock-ins and signal averagers, were usually used as part of more complex systems including rack-mountable products from a variety of manufacturers as well as oscilloscopes, strip chart recorders, and so forth. For PAR’s first foray into analytical instrumentation, we had decided that we had to offer a complete system. This would include an xy plotter that would allow us to ensure that current was plotted as a function of voltage, rather than of time. Earlier instruments had used strip-chart recorders, and essentially assumed that the applied potential was linear with time. In all the PAR products, the actual applied potential was used to drive the x axis of the recorder, giving much more accurate and reproducible data. It was also felt that the whole thing had to be in a single cabinet except for the electrode assembly and that we had to make the cabinets and panels impervious, or at least resistant, to corrosive chemicals. We wanted the instrument to retain the PAR “look”, which at that time consisted of gray-paint front panels, a box made from aluminum extrusions, and blue vinyl-coated aluminum sheet panels. Drafting came up with a package design for a console with a sloped front panel and a bed for the xy plotter that looked reasonable. As the sole chemist in the company, I was charged with selecting materials and vendors for the “resistant” package components. In the lab, we determined that the blue vinyl-clad aluminum sheets were adequately resistant, but the gray-painted front panels peeled when attacked by either 40% NaOH or concentrated H2SO4. In retrospect, anyone who dumped concentrated acid or base on his instrument deserved the consequences, and we probably should have tested only for resistance to coffee. I found vendors for front panels made out of engraved and filled anodized aluminum. These panels would resist anything we threw at them. They probably cost a fortune, but at the time I had not yet learned to worry about such minor details as material costs. For the cabinet, however, we ran into a different problem. The vinyl-clad aluminum was sufficiently resistant to chemicals, but it was not strong enough to use for the cabinet unless it was built on a frame of solid metal “girders” of some sort. By the time we had reached this point, enough of the design had been completed for us to be forced into the dimensions originally specified by drafting, and there simply was not enough room to add support girders to the cabinet and still fit all the bits and

pieces inside. The mechanical designers said that sheet steel would be strong enough to build the cabinet as a simple “weldment” without supporting members, but no one made vinyl-clad sheet steel! After considerable digging, we found a vendor in western New York State near Buffalo. This organization could fabricate the cabinets out of sheet steel and then paint them with a crackle finish vinyl paint that would meet our chemical resistance requirements and actually looked like the PAR aluminum sheets. We gave him the order for some prototypes and moved on to other things.

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Switching While all these cabinet design and panel issues were going on, we had to convert the design concepts into an instrument. Most of the amplifier circuits had been built and tested, and everything seemed to work well. However, all the experiments had been performed by connecting the various breadboards together with clip leads—actual switches and front panels had never been built. We had invented a front-panel design, but it fell to me to figure out the switching required to implement the functions and the wiring for all the interconnects. In those days, programmable solid-state switches did not exist and everything was analog. To implement the various functions we had so fearlessly come up with, each function switch had to be designed as a multiwafer, multiwiper rotary switch that could interconnect the various circuit elements in different ways for each different function. Figure 13 shows front and rear views of a single-wafer, commercial, 6-pole, 2-position rotary switch. A diagram such as this is used by the designer to figure out the exact wiring configuration to be used to accomplish the functions. They differ from the typical representation of a switch found in a circuit schematic in that the actual wafer geometry is shown. In the case of a simple switch such as this one, the wiring is obvious. Range switches were also easy, but the function switches were a nightmare. In the case of the 170, we had to employ complex, multiwafer switches that had as many as 8 positions. Since the types of connections varied widely, depending on whether current or voltage was being measured, for example, the switching functions were not linear, but rather involved changing many different interconnects simultaneously. To create such custom switches, we had to start from a blank wafer diagram as in Figure 14 and come up with complex wiper configurations that would perform entirely different interconnects at different rotation points. We then had


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Figure 15. Single wafer of a multiwafer, multipole function switch.

to figure out how to make all the necessary connections, and only the necessary connections, by connecting different parts of different wafers together on the same switch. One wafer of such a switch configuration is shown in Figure 15, but most of the function switches in the 170 were 5 and 6 wafers deep! The eventual wiring diagram of the 170, which included all the switches and interconnections, was on a roll of paper 12 feet long by four feet high! Construction After a first pass at the wiring diagram was completed, the next step was to assemble the first complete prototype. Most of the individual circuit boards had already been built and tested in some form, using either wire-wrap or point-topoint construction, and in some cases, first-pass printed boards already existed. It was a long way, however, from working individual boards to a complete, interconnected instrument. The board cage had to be constructed and, most importantly, all the wiring that connected the individual pins on the boards to the switches on the panel and the pins on other boards had to be installed. The power supply was built on a separate chassis that slid in and out of the bottom of the cabinet, but the amplifier card cage was designed to be mounted above it in a fixed position. The boards could be accessed from the rear, while the board connectors were on the front side so that the wires from them to the actual front-panel switches need only be long enough for adequate service loops when the front panel was opened. It was simply not feasible to ask the typical production worker to follow a detailed wiring diagram as complex as the one involved and connect things pointto-point. Thus, to make production of this device feasible, it was necessary to design a wiring harness, a package of wires cut to length, stripped and tinned, and tied together in such a way as to allow a relatively unskilled worker to simply lay it in place and solder all the connections. At that time, PAR had a woman who was a wiring miracle worker. Veronica Gibbons, known as Ronnie, could take a hand-drawn wiring diagram and a bunch of hardware and wire up the complete chassis neatly and compactly, while documenting what she did, so that the harness could then be built outside as a unit. Harnesses were made by outside vendors, with wires laid down on a “bed of nails” constructed on a sheet of wood. The completed, tie-wrapped harness could then be installed and connected more quickly and neatly than if someone had to individually route each wire. All this depended upon Ronnie, as she did the harnesses for all PAR products.

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The eventual wiring harness of the 170, as originally constructed by Ronnie from my 12-foot diagram, had 400 wires in it and was an inch thick! Soon, we received the first two prototype cabinets from the sheet-metal vendor. They arrived nice and neat, covered in blue-vinyl paint, and looked exactly as they should. The color matched the PAR aluminum, the dimensions were correct, and everyone was happy. However, as we started to install components inside, a slight problem developed. The blue paint peeled off in sheets as soon as it was touched! Disaster! We were now only a few months away from Pittcon, the prototypes really could not be tested spread out along a bench, and we had no cabinets. We sent the cabinets back to the vendor, whereupon he revealed that he had had no experience in using the particular vinyl paint we specified on steel surfaces. All his previous work had been done on aluminum cabinets. We subsequently found out that the steel materials used were always lightly coated with oil as they moved around the factory, to prevent rust formation. The usual “pickling” baths, which treated the cabinetry before painting, would remove dirt and grease from aluminum cabinets but were not strong enough to get the last traces of oil off the sheet steel units. They had to use a stronger, multipledip pickle to clean the steel cabinets before painting. It was quite fortunate that we discovered this problem at the prototype stage rather than on instruments that had been shipped to customers. Pricing Meanwhile, a business issue was rearing its head. It was now late fall, and we were still aiming for a Pittcon introduction in March. PAR at this point had no computers in its manufacturing operation. When a subassembly was designed and drawn up in the drafting department, a bill of materials was placed upon the drawing. This table simply listed the reference drawing numbers or part numbers of each of the components used in the particular subassembly. Purchasing, on the other hand, needed a complete parts list for the entire instrument. A pile of separate lists, one for each of a very large number of drawings, was no help to them. Only with one consolidated list could they determine total quantities and thus obtain maximum discounts. To convert the bills of materials on the drawings into something that purchasing could use to find vendors and determine prices, a truly high-tech procedure was employed. A blueprint of each subassembly drawing was sliced up by hand, the slices were sorted by part number, and then a total purchasing parts list was pasted up from the slivers of paper, with quantities indicated by the number of slivers! The first destination of these lists was purchasing, which had to actually go out and buy parts for production, but another use was to determine what the material cost was, so as to allow a selling price to be set. For parts such as standard electronic components that were already in use in other products the cost was known. However, this instrument used many new parts whose cost had to be determined through the purchasing process, which in turn required complete and accurate parts lists. Even though the cut-and-paste technique could produce these lists, the design first had to be complete. At


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that point in time that was far from true—some subassemblies had not yet been designed and others were rapidly changing. Purchasing was getting quotes on the parts and trying to price out each parts list, but the information was incomplete. Nonetheless, we were approaching a deadline for announcing a selling price—Pittcon was looming and we had to print literature, notify foreign distributors, and so on. My education, to that point, had been in science. I had degrees from both the Polytechnic Institute of Brooklyn and New York University. However, at Poly, business education was unheard of. At NYU, people who went to the School of Commerce where business studies were offered were looked down upon by the “elite” at Arts & Science. My exposure to business education had been limited to flunking some students in my quantitative analysis course. I did not know one end of a profit and loss sheet from the other and had no idea how to read a balance sheet. Sometime in early December, I was notified that the time had come to schedule a pricing meeting. Since there was no marketing group and no sales force, the meeting was attended by the lady from drafting who compiled the parts lists, the controller, the company president, and me. At this point, no one had seen a finished instrument, no one in manufacturing had any idea what was involved, and purchasing had pricing on only a portion of the total parts list. There were standard factors for the percentage that parts should represent of the total cost of a product and for the overhead burden on manufacturing labor—how much to add to the hourly labor cost to account for supervision, purchasing, and so forth. However, all the factors were based on the standard PAR 19-in. wide rack-mounted box of electronics, a very different animal from the 170. Thus, operating from our usual complete lack of knowledge, people made their estimates, the numbers were added up, and the total estimated cost came out to be ∼$6,000. When I was then asked what the selling price should be, I figured that they wanted a 15% profit margin, so I said the price should be $6,900! This highly naïve statement of course completely ignored the need to pay for R&D, marketing and sales, general company administration, facilities, insurance, etc., etc., etc. After some discussion, we set the price at $9,500. I wanted to keep it below $10,000, an approval threshold for many agencies and universities, while Wendy Lehmann wanted to set it as high as possible since he knew the numbers were incomplete. Wendy, as was usually the case, turned out to be correct, and the price was later raised a number of times. The Perils of Export Markets and Documentation All the problems we had with the cabinet produced another interesting side effect. We planned to introduce the instrument at Pittcon in March and had also planned to send it to our European office in France for an exhibition later in the year, to be followed by a tour through various countries in Europe to introduce the product. Normally, in those preEU days, carrying demo equipment from one country to another meant clearing customs twice for each border and took an interminable quantity of time. However, the United States had just become a party to an international agreement under which products for exhibition purposes could be transported

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across borders without paying customs duties, if appropriate paperwork was included. This paperwork, known as an ATA Carnet, consisted of detailed descriptions of the product and a pile of forms, one of which had to be stamped by both incoming and outgoing customs in each country as the borders were crossed. In midwinter, as we were madly trying to get ready for Pittcon, a secretary from the export department hunted me up and asked for the precise weight of the product. Since we had not received a cabinet and had not constructed a finished prototype, and more importantly since I had no clue as to why this mattered, I made a completely wild guess as to the weight. This later turned out to be a huge problem that fell squarely upon my shoulders when I made my first trip to Europe to give seminars and demonstrate the equipment. Our first stop was Switzerland, and it turns out that Swiss Customs duties are based at least partially on the weight of the shipment. I arrived at the Zurich airport on my very first trip, speaking only a little German and no Schweizerdeutsch dialect, to find that the customs inspectors would not clear my shipment. It seems that it weighed substantially more than the weight quoted on the Carnet while it was in its package, and substantially less when it was unpacked! It took a great deal of effort, in quite a few languages, before we finally got out of the airport. We Were Not Alone! At the time, I assumed that much of our difficulty arose from my complete lack of experience and PAR’s unfamiliarity with chemistry markets. As it turns out, this was only partially true, and more experienced suppliers with worldwide reputations encountered similar problems. The 170 included a built-in xy plotter. PAR obviously was not going to make these, and we sought a vendor to supply them. The original prototype contained plotters from one vendor with inadequate slewing speed. We wanted to allow users to do reasonably fast cyclic voltammetry without connecting an external oscilloscope and also to do classical dc polarography with natural drops. This need for speed meant that we were looking for a fast plotter. We thus threw open the bidding to all suppliers when we sought plotters for the production instruments. We obtained samples from a number of suppliers and had just about made our decision based primarily on price as they all seemed to perform about equally well. However, one well-known purveyor of plotters was unhappy with the fact that we had not chosen their offering. I explained that their price was 50% above the other vendors. Their device had better specifications, but only in areas that did not matter for our application. The local salesman then told me that they had a new product, not yet announced, which he thought would be perfect for our application as to both price and as to performance. He took me out to their plant to see the prototype and I was impressed. Since this supplier was a much more established name than any of our other choices and since this new product seemed so good, we decided to give them the contract and ordered 3 plotters for prototypes and 10 for the first production run. Delivery was promised by the end of the summer, which was when we planned to ship our first orders.


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Figure 16. Model 170 electrochemistry system.

Figure 17. Model 171 polarographic analyzer.

Sometime later, the first two plotters came in. We installed them in the lab prototype instruments and began our testing. I was called away for something, and when I returned, I found Frank and Marty scratching their heads. The plotter had worked for a few minutes, but then it suddenly died, and nothing they could do would bring it back. We pulled it out of the cabinet and tried to figure out what had happened. We had the schematics and circuit board diagrams so we started a troubleshooting procedure to find the problem, but got nowhere for quite some time. Power was coming out of the power supplies and going to the main board, but nothing was happening at the other end. We traced and measured and troubleshot for quite a while and could not figure out the problem, when Frank happened to notice a resistor lying in the bottom of the cabinet. It was a 10 KΩ metal film resistor, but it was not the brand that we used at PAR and was a different color. Sure enough, it turned out to be the same brand and color as was used on the xy plotter. With that hint, we began to carefully examine the circuit board, comparing it to the labeled photograph that had been supplied in the manual, and eventually found two empty solder pads where the diagram showed a resistor. The 10 KΩ resistor we had found was the feedback gain control resistor for the main signal amplifier in the recorder. The unit we had received was a prototype, and even though it had printed boards, the boards had been hand-assembled and the component leads were not crimped and bent to the board. The resistor had overheated so badly that it literally melted the solder and fell out of the board! Apparently, in an effort to get the maximum speed out of the plotter, the vendor had designed it with no filtering networks in the feedback loops, assuming that the signals people were trying to plot would be sufficiently clean as to obviate the need for such networks. In our case, since oscilloscope readout was always an alternative for faster experiments, there was no fixed filtering in the signal processing networks.

The user could apply a time-constant or not as he wished, and with the time constant off, the signal could contain a good bit of noise—enough to overload the amplifier as it tried to drive the y axis motor back and forth at high speed responding to the noisy signal. The resistor heated up enough to melt the resistor’s solder joints. An interesting approach to fusing. We chose another vendor.

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Despite All, Pittcon Arrived These were the sorts of things that happened throughout the project. We had no professional product engineering staff and no experienced manufacturing engineers. In fact, we had no one with any experience at all except for Frank Eckert and Ronnie Gibbons, and they were not in supervisory roles. We muddled along, improvised and ad-libbed, crossed our fingers, and prayed. With a lot of perseverance, many hours, and incredible good luck, we managed to get one 170 prototype, with hand-wired boards and lacking some features, assembled in time for Pittcon (Figure 16). The 171, which was the simpler polarograph version, was not completed until somewhat later (Figure 17). We always felt that building the more complex instrument first was the right thing to do, since it was always easier to remove features than to cram them into an already-finished design. This was probably a wise decision, because while the 170 sold well for quite a few years, the 171 was a complete flop! I doubt if we sold even 10 instruments in total. After Pittcon, we came back with a lot of inquiries, people ready to buy, wanting quotations, delivery dates, and so on. However, there was a still a great deal of work to be done to get the instrument into production and we worked extremely hard for about another 6 months before things lightened a bit and we could deal with other issues, like training a sales force, developing a marketing campaign, or even thinking about the next products.


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strument was awarded the IR100 award in 1968, and the “hardware” article initially presented at Pittcon was the lead article in one of the early issues of American Laboratory magazine, in February 1969 (Figure 18). This rather artsy picture was taken of a real DME in a real solution. We took the picture in our own lab late at night, using a quickly-built trigger circuit to fire the flash just before the drop was dislodged. It probably took 20 exposures until we got one that worked, and this was before the free “film” of digital photography! Conclusions

Figure 18. Magazine cover from American Laboratory, February 1969 (published with permission).

The recorder problem occurred as we were getting the 170 into production. We began delivering units in the summer of 1968 and the unit remained in production for quite a few years, yielding good results for many researchers. The in-

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One thing I learned at PAR was that successful instrument development requires that the specifications of the product be pretty well frozen before the actual design effort is begun. Obviously, you need to try some things, build breadboards, test concepts, and so forth. However, starting on the actual design of a product—freezing even the package concept or the geometry—before all the specs have been set forth and all the parameters have been established is a recipe for at least excessive costs and time, if not total disaster. As a consultant, I often tell people that my contribution is to prevent them from making mistakes I have already made, and this first project at PAR was a perfect example of a long list of mistakes. The eventual result was a good one, and we even managed to meet some of the deadlines by putting in incredible hours and having an extraordinary run of good luck. The way we did it, however, worked only because the production runs were small, the market was forgiving, the technology was fairly primitive, and we were extremely lucky. Literature Cited 1. Evilia, Ronald F.; Diefenderfer, A. James. Anal. Chem. 1967, 14, 1885–1887.


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Genesis of the Electrochemical Instrumentation at ... - ACS Publications

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