Rethinking a Timeless Titration Experimental Setup through

May 13, 2019 - ... a Timeless Titration Experimental Setup through Automation and Open-Source ... across teaching laboratories from high school to uni...
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Rethinking a Timeless Titration Experimental Setup through Automation and Open-Source Robotic Technology: Making Titration Accessible for Students of All Abilities Ronald Soong,* Kyle Agmata, Tina Doyle, Amy Jenne, Antonio Adamo, and Andre J. Simpson University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada

J. Chem. Educ. Downloaded from pubs.acs.org by 94.231.219.189 on 05/13/19. For personal use only.

S Supporting Information *

ABSTRACT: Titration is a common introductory experiment performed across teaching laboratories from high school to university. Yet, its setup remains inaccessible for students with disabilities, denying them the opportunity for experiential learning. Therefore, rethinking such a setup is required to increase laboratory participation for these students. To remove these physical barriers, an automated titration unit based on existing undergraduate titration setups and universal design concepts, coupled with text-to-speech (TTS) capability, is presented. This unit can connect seamlessly via Bluetooth to any mobile platform and takes advantage of the advances in assistive features, such as TTS, on either a tablet or a smartphone. The cost of this unit is between $300 and $500, not including the cost of the smartphone or tablet. However, with the popularity of mobile devices in our society, these devices are becoming highly affordable, and almost every undergraduate is equipped with such a device. Also, with the emphasis on coding literacy, this autotitration setup serves as an excellent example and exercise on design thinking and automation in an undergraduate chemistry lab. KEYWORDS: First-Year Undergraduate/General, Laboratory Equipment/Apparatus, Analytical Chemistry, Collaborative/Cooperative Learning, Laboratory Computing/Interfacing

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INTRODUCTION

Despite our best efforts, students with disabilities often question their aptitudes in STEM (science, technology, engineering, and mathematics) due to the lack of opportunity and accommodation resources.1−4 Understanding that laboratory assistive technology can be expensive, ranging in the thousands of dollars, students with disabilities are frequently excluded from many laboratory activities.5 Many exercises are designed for able-bodied students with specific learning outcomes.4 Over the years, efforts have been made to increase the participation of students with disabilities through sensory replacement activities.6,7 While titration is a commonly used introductory analytical technique in many teaching laboratories, its setup remains inaccessible for students with disabilities as shown in Figure 1. Therefore, only able-bodied students can satisfy these physical requirements, which creates unnecessary barriers to learning for students with disabilities.4 With the understanding that science should be accessible for all, a rethinking of the traditional titration setup is required through the universal design (UD) concept.8−10 The utilization of UD is wellcelebrated in the accessibility community and often used to eliminate not only physical barriers in building spaces, classrooms, and laboratories, but also the learning barriers for instructional materials.8−10 Therefore, UD concepts can be used to adapt the current equipment for students with accessibility needs, allowing them to gain greater access to © XXXX American Chemical Society and Division of Chemical Education, Inc.

Figure 1. Illustration depicting the traditional titration setup in an undergraduate lab showing various potential physical barriers for students with different disabilities.

experiential learning while achieving the learning outcomes through participation in laboratory exercises.4,8−10 Received: January 10, 2019 Revised: April 22, 2019

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DOI: 10.1021/acs.jchemed.9b00025 J. Chem. Educ. XXXX, XXX, XXX−XXX

Journal of Chemical Education

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Figure 2. (A) Picture depicting the assembly of the Arduino unit with 1Sheeld+ module and sensor expansion shield. (B) A schematic illustrating how each component is connected to the unit.

Given this circumstance, we have designed an affordable autotitration unit based on the UD concept that addresses the accessibility gap in titration experiments using existing laboratory equipment. Since titration is a common experiment found in most chemistry curricula, addressing this accessibility gap will have a profound impact on learning for students with disabilities. Successful automation of an existing titration setup has been demonstrated in previous reports.11,12 These setups consisted of either a solenoid valve or a plastic reagent reservoir fitted with a double stopcock as a mean to control dispensing of droplets. However, features, such as TTS and large readout display, needed for students with disabilities are absent. Therefore, these designs can be further improved to allow greater access for students with disabilities. This UD titration setup uses an Arduino open-source microcontroller, coupled to a Bluetooth enabled shield called 1Sheeld+, and a servo to control the stopcock on a buret for precise autodispensing of liquid. This Bluetooth shield allows the Arduino to pair seamlessly with either a smartphone or tablet that runs on either an Android or iOS operating system via the 1Sheeld+ app, allowing the Arduino unit to take full advantage of the assistive functionalities of your mobile device, including TTS and data storage/logging capability. The total cost of this setup is between $300 and $500, an affordable alternative to a commercial setup, which cost in the range of thousands of dollars.5,7 Also, with the increased emphasis on coding literacy, this UD autotitration setup serves as an excellent example and exercise on design thinking and automation in a chemistry lab.

(7) Zip ties (8) USB printer transfer cable (9) MacBook Air 2012 Sample codes and the connection diagram (see Figure S1) can be found in the Supporting Information. All chemicals used were purchased from Sigma-Aldrich unless otherwise specified. An enclosure box was 3D printed at the UTSC (University of Toronto Scarborough) Library MakerSpace. The 3D printer used was a MakerBot Replicator 2 using PLA (polylactic acid) filament as the substrate for printing. The assembly of the Bluetooth Arduino unit is illustrated in Figure 2.

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HAZARDS NaOH, sodium hydroxide, is a corrosive substance. Regardless of concentration, gloves, eye protection, and a lab coat should be worn before handling the substance. If liquids are spilled on the Arduino unit, unplug the power source and remove all the components from the Arduino unit. Wipe the Arduino unit down for any excess liquid and allow the unit to air-dry overnight before testing its functionality.

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DISCUSSION The assembly of the Arduino unit is simple and straightforward. Both the 1Sheeld+ Bluetooth module and the sensor expansion shields can be easily snapped onto the Arduino without soldering. The pairing between the 1Sheeld+ and a smartphone via Bluetooth is seamless with detailed instructions given on the manufacturer’s website.14 Once the devices are paired, the functionality can be selected on a smartphone to indicate that you want the Arduino to incorporate the 1Sheeld+ app. This device offers several advantages and improvements in addition to TTS over the previously reported MUCSH:5 (1) remote control capability, (2) expanded functionality without additional cost, (3) large screen readout for sensor values, and (4) reduction of the demand for memory on the Arduino units for data storage (see Supporting Information for more details). The 1Sheeld+ mobile app offers a comprehensive list of

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MATERIALS AND METHODS The following hardware was purchased from RobotShop Inc.:13 (1) Arduino UNO (2) Arduino expansion sensor shield (3) 1Sheeld+ Bluetooth shield (4) Jumper cables (5) Gravity analog pH meter kit (6) Servo (Hitec 32225S HS-225MG) B

DOI: 10.1021/acs.jchemed.9b00025 J. Chem. Educ. XXXX, XXX, XXX−XXX

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Technology Report

Figure 3. (A) Illustration depicting the assembly of a UD autotitration setup adapted from existing laboratory equipment. (B) A picture of the autotitration setup with the servo connected to the stopcock on the buret and controlled via Arduino. The readings from the pH electrodes are recorded via the Arduino, and the values are sent through Bluetooth to the smart phone through the 1Sheeld+ app. The pH values are also audibly outputted through the TTS capability of the app. (C) Servo attachment to the stopcock on the buret. The handle on the stopcock is strapped to the horns on the servo using zip ties and caped with a short piece of silicone tubing. (D) Arduino hardware setup with sensor expansion shield and 1Sheeld+ Bluetooth module.

this device in automating a titration experiment, a titration was performed in which H3PO4 in Pepsi-Cola soda was titrated against NaOH. An Arduino program was written (see Supporting Information) such that the device will audibly output the pH values after each injection from a buret. The dispensing of liquid from the buret is controlled via a servo, allowing the system to automate the titration. (Note: After each injection, the system will wait 10 s before taking a pH reading, allowing the system to reach equilibrium.) The resulting titration curve shown in Figure 4 is consistent with the literature. The calibration of volume per automated injection via a buret was performed according to the literature.11 On the basis of our calculations from three titration trials (see Supporting Information), the concentration of H3PO4 is approximately 4.59 ± 0.077 mM, which is

functionalities. For accessibility purposes, TTS, datalogging, voice control, and color detector are features that can be easily added to your system with minorprogramming. The programming of this unit was simple, and its operation is straightforward: sensors as well as servos can be easily attached to the pins on the sensor expansion shield. Importantly, once the data is collected, it can be transferred to the mobile device via Bluetooth for storage as either a .txt or .csv file format in the OneSheeld/Datalogger directory. Also, the pH value can be audibly outputted via TTS of the app.14 An illustration of the titration setup is shown in Figure 3. A project enclosure should be used to protect the unit from chemical spillage but is not necessary for its operation. The small form of this device makes it easy to incorporate into any experimental setup. To illustrate the applicability of C

DOI: 10.1021/acs.jchemed.9b00025 J. Chem. Educ. XXXX, XXX, XXX−XXX

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affordable and a common fixture for many students. Therefore, the ability to pair with a mobile device makes it convenient for students as our titration system is built on well-supported platforms: iOS and Android. Last, with the increased emphasis on coding literacy at the undergraduate level, this UD autotitration unit provides an excellent example of design thinking and programming, modernizing the current chemistry curriculum.

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CONCLUSION In this technology report, we present a UD autotitration unit that bridges the accessibility gap in the teaching laboratory. This autotitration unit is based on the concept of universal design that allows users of all abilities to perform a titration experiment. All experimental data can be stored, and output is audible through a smartphone or tablet using Bluetooth. The cost of this device is a fraction of that of a commercially available assistive device and offers comparable features. With the increased emphasis on coding literacy, this UD autotitration setup serves as an excellent example and exercise in design thinking and automation in an undergraduate chemistry curriculum.

Figure 4. Sample titration curve of 30 mL of Pepsi-Cola soda with 0.05 M of NaOH solution via an autotitration unit.

acceptable compared with literature values of 5.03 mM, validating the accuracy and precision of our approach.15 This UD autotitration setup allows students with various disabilities, such as visual impairments, or the inability to reach and turn a stopcock on a buret, to perform and participate in a titration experiment. This titration setup is an improvement over the micropipette titration approach for students with disabilities as it removes the manual dexterity requirement for any liquid handling reserved for able-bodied students.5 While this system only addresses the titration aspects of the experiment, assistance is still required for equipment setup, volume measurements, and dilution. Furthermore, with a few modifications it is possible to adapt this titration setup to other undergraduate experiments, such as potentiometric titration, conductometric titration, and complexometric titration.16−19 For example, conductometric titration can be performed via connecting a conductivity electrode to the analog port of the Arduino.19 As for potentiometric titration, construction of a potentiostat is required, and instructions for this can be found elsewhere.20 Therefore, this automation approach removes most of the unnecessary physical barriers to learning for students with disabilities. However, at some point, this automation approach may become impractical if the end point is qualitatively determined, such as with the use of a color indicator, instead of quantitively determined via electrochemistry. Since the intensity of color is affected by numerous environmental factors, including the illumination source, this can make it difficult for automation, and a machine learning approach may be required. This device is highly flexible and can be reprogrammed to accommodate different needs without significantly compromising a student’s learning experience. This can be done with modifications including remote control turning of the stopcock, or using the detector on your smartphone to detect the color change at the end point with the aid of a machine learning algorithm (see Supporting Information).21,22 While the ability to incorporate mobile device sensors offers flexibility in project design, it is not always necessary. In fact, exploring new sensors and opensource modules can offer insights into new applications and experiments in the sciences. Therefore, the aim of this UD setup is to retain the experiential aspect of learning, while using automation to overcome physical barriers pertaining to this learning experience. While this is a significant improvement compared to the MUCSH,5 the additional cost of a tablet or a smartphone may be an issue in some schools. However, with the advances in technology, mobile devices are becoming

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.9b00025. General instructor notes, titration experiment, sample code, sample student handout for the experiment, and sample instructor note for the experiment (PDF, DOCX)

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Ronald Soong: 0000-0002-8223-9028 Andre J. Simpson: 0000-0002-8247-5450 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We acknowledge the University of Toronto Scarborough and the University of Toronto Scarborough MakerSpace for their generous support for this project. In addition, we acknowledge seed funding support from the Instructional Technology Innovation Fund from the University of Toronto.

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REFERENCES

(1) Sevo, R. Literature Review: Disabilities and Diversity in Science and Engineering. Recomm. Read. Disabil. Divers. Sci. Eng. B. Bogue E. Cady. Apply Res. to Pract. Resour. 2012, 1−18. (2) Shanahan, J. Disability Is Not a Disqualification. Science (Washington, DC, U. S.) 2016, 351 (6271), 418. (3) Brown, E. The Fight for Accessibility. Nature 2016, 532 (7597), 137−139. (4) Sukhai, M. A.; Mohler, C. E. Creating a Culture of Accessibility in the Sciences; Academic Press: New York, 2016. (5) Soong, R.; Agmata, K.; Doyle, T.; Jenne, A.; Adamo, T.; Simpson, A. Combining the Maker Movement with Accessibility Needs in an Undergraduate Laboratory: A Cost-Effective Text-to-

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Speech Multipurpose, Universal Chemistry Sensor Hub (MUCSH) for Students with Disabilities. J. Chem. Educ. 2018, 95 (12), 2268− 2272. (6) Pereira, F.; Mata, P.; Aires-de-Sousa, J.; Lobo, A. M.; et al. Sonified Infrared Spectra and Their Interpretation by Blind and Visually Impaired Students. J. Chem. Educ. 2013, 90 (8), 1028−1031. (7) Costa, S. C.; Fernandes, J. C. B. Listening to pH. J. Chem. Educ. 2019, 96 (2), 372−376. (8) Basham, J. D.; Marino, M. T. Understanding STEM Education and Supporting Students through Universal Design for Learning. Teach. Except. Child. 2013, 45 (4), 8−15. (9) Silver, P.; Bourke, A.; Strehorn, K. C. Universal Instructional Design in Higher Education: An Approach for Inclusion. Equity Excell. Educ. 1998, 31 (2), 47−51. (10) Hitchcock, C.; Stahl, S. Assistive Technology, Universal Design, Universal Design for Learning: Improved Learning Opportunities. J. Spec. Educ. Technol. 2003, 18 (4), 45−52. (11) Famularo, N.; Kholod, Y.; Kosenkov, D. Integrating Chemistry Laboratory Instrumentation into the Industrial Internet: Building, Programming, and Experimenting with an Automatic Titrator. J. Chem. Educ. 2016, 93 (1), 175−181. (12) Cao, T.; Zhang, Q.; Thompson, J. E. Designing, Constructing, and Using an Inexpensive Electronic Buret. J. Chem. Educ. 2015, 92 (1), 106−109. (13) RobotShop. www.robotshop.com/ (accessed Apr 2019). (14) 1Sheeld. https://1sheeld.com/ (accessed Apr 2019). (15) Murphy, J. Determination of Phosphoric Acid in Cola Beverages: A Colorimetric and pH Titration Experiment for General Chemistry. J. Chem. Educ. 1983, 60 (5), 420. (16) Grabowski, L. E.; Goode, S. R. Determining a Solubility Product Constant by Potentiometric Titration To Increase Students’ Conceptual Understanding of Potentiometry and Titrations. J. Chem. Educ. 2017, 94 (5), 636−639. (17) Belle-Oudry, D. Quantitative Analysis of Sulfate in Water by Indirect EDTA Titration. J. Chem. Educ. 2008, 85 (9), 1269. (18) Yang, S.-P.; Tsai, R.-Y. Complexometric Titration of Aluminum and Magnesium Ions in Commercial Antacids. An Experiment for General and Analytical Chemistry Laboratories. J. Chem. Educ. 2006, 83 (6), 906. (19) Garcia, J.; Schultz, L. D. Determination of Sulfate by Conductometric Titration: An Undergraduate Laboratory Experiment. J. Chem. Educ. 2016, 93 (5), 910−914. (20) Meloni, G. N. Building a Microcontroller Based Potentiostat: A Inexpensive and Versatile Platform for Teaching Electrochemistry and Instrumentation. J. Chem. Educ. 2016, 93 (7), 1320−1322. (21) Bandyopadhyay, S.; Rathod, B. B. The Sound and Feel of Titrations: A Smartphone Aid for Color-Blind and Visually Impaired Students. J. Chem. Educ. 2017, 94 (7), 946−949. (22) Häse, F.; Roch, L. M.; Kreisbeck, C.; Aspuru-Guzik, A. ChemOS: Orchestrating Autonomous Experimentation. Sci. Robot. 2018, 2−4.

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DOI: 10.1021/acs.jchemed.9b00025 J. Chem. Educ. XXXX, XXX, XXX−XXX