Multilayered Ag NPs-PEDOT-Paper Composite Device for Human

Subscriber access provided by UNIV OF NEW ENGLAND ARMIDALE

Surfaces, Interfaces, and Applications

Multilayered Ag NPs-PEDOT-Paper Composite Device for Human-Machine Interfacing Yi-Jie Tsai, Chang-Ming Wang, Ta-Sheng Chang, Sanjeeb Sutradhar, Che-Wei Chang, Chong-You Chen, Chia-Han Hsieh, and Wei-Ssu Liao ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b21390 • Publication Date (Web): 14 Feb 2019 Downloaded from http://pubs.acs.org on February 15, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Multilayered Ag NPs-PEDOT-Paper Composite Device for Human-Machine Interfacing Yi-Jie Tsai,† Chang-Ming Wang,† Ta-Sheng Chang, Sanjeeb Sutradhar, Che-Wei Chang, Chong-You Chen, Chia-Han Hsieh, and Wei-Ssu Liao* Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan

*To whom correspondence should be addressed: [email protected] (W.S.L.) †These authors contributed equally

KEYWORDS. Sensor, conductive polymer, nanoparticle, filter paper, interface

1

ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ABSTRACT

Flexible pressure sensors have attracted increasing interest due to their potential application on wearable sensing devices for human-machine interface connections, but challenges regarding material cost, fabrication robustness, signal transduction, sensitivity improvement, detection range, and operation convenience still need to be overcome. Herein, with a simple, low-cost, and scalable approach, a flexible and wearable pressure sensing device fabricated by utilizing filter paper as solid support, poly(3,4-ethylenedioxythiophene) (PEDOT) to enhance conductivity, and silver nanoparticles (Ag NPs) to provide a rougher surface, is introduced. Sandwiching and laminating composite material layers with two thermoplastic polypropylene films lead to robust integration of sensing devices, where assembling four layers of composite materials results in the best sensitivity toward applied pressure. This practical pressure sensing device entailing properties of high sensitivity of 0.119 kPa-1, high durability of 2000 operation cycles, and an ultralow energy consumption level of 10 -5 W, is a promising candidate for contriving point-of-care wearable electronic devices and applying to human-machine interface connection.

2


Page 2 of 36

Page 3 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


INTRODUCTION Flexible pressure sensing devices have recently attracted great amount of interest due to the potential wide applications on wearable electronics,1-4 electronic skins,5-6 smart robotics,7-8 and human-machine interfaces.9-12 To realize these practical usage, essential properties including high mechanical flexibility, great detection sensitivity, broad pressure measurement range, and harmonized signal responding interfaces are required. However, the current reported pressure sensing devices with high sensitivity are usually limited to small applicable pressure ranges (25 kPa) exhibit a lower sensitivity.15-18 Besides, the commonly adopted sophisticated fabrication techniques based on photolithography or chemical etching raise barriers to economical large-scale device production.19-22 It is therefore highly urgent to develop a pressure sensor featuring high sensitivity, broad pressure range, good repeatability, simple fabrication process, and low power consumption. Among different types of pressure-responsive mechanisms, piezoelectricity-,23-26 piezocapacitivity-,19, 27-31 and piezoresistivity-based13, 32-36 approaches are commonly utilized for sensing device assembly due to their robustness and outstanding performance in stimulus induced response. Piezoelectric pressure sensors rely on piezoelectric effects caused by an external, pressure-induced potential change, and can therefore be self-powered and operated without external power sources.25-26 Piezocapacitive pressure sensors record the capacitance change upon external pressure, and respond to deformation induced by changes on dielectric layer contacting area,19, 27 distance between electrodes,31 or material’s effective permittivity.30 Alternatively, a piezoresistive pressure sensor detects changes in device resistance under pressure stimulus, which can be achieved by measuring changes in applied voltage or current when one of them is fixed. Due to advantages of convenient signal collecting, simple

3



Page 4 of 36

fabrication procedure, and high device durability,13, 17, 29, 32-42 developments of piezoresistive pressure sensors have expanded very rapidly in recent years. The performance of a piezoresistive pressure sensor depends on two main factors: (1) active material selection and (2) substrate geometry control. A wide range of conductive materials, including carbon nanotube (CNTs), graphene,35, hydrogel,42 and conductive polymer24,

51-52

43-46

metal nanowire,30,

47-50

have been used as active materials for

piezoresistive pressure sensing. Selection of these materials depends on effective conductivity, fabrication cost, treatment convenience, robustness, and ease of operation when integrating with other device components. Regarding substrate geometry controls, rough materials or those with hierarchical structures such as sponge, fiber, and foam, are preferred, due to more sensitive response provided by larger resistance changes through higher effective contacting areas.19, 21, 27, 30, 52-54 Soft-materials, such as polydimethylsiloxane (PDMS) and hydrogel, are also favorable options due to their high flexibility and feasibility in structure manufacturing.13-14,

19, 30, 37, 53

For example, rougher structured PDMS with microscale

three-dimensional patterns have been reported to further enhance the sensitivity of pressure sensing devices by approximately 30 times compared to the devices fabricated with a planar substrate.19 Furthermore, their performance is also controllable with the manipulation of micro structure array dimensions.14 Recently, paper-based electronics have attracted increasing interests due to their advantages of low cost, lightweight, simple fabrication, environmental friendliness, and flexibility on various platforms such as energy storage devices,55-56 transistors,57 and electronic circuits.58 Relying on paper substrate’s porous structure and mechanical flexibility, this material can also be applied to designing pressure sensors.59-60 Important issues regarding performance of a paper-based piezoresistive pressure sensing design lie in both material conductivity and effective deformation induced resistance change. Taking advantage of the porous structure

4


Page 5 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


paper material renders, a significant task is to provide paper with a higher conductivity. Although various conductive material candidates exist, conductive polymers are superior selections due to their great conductivity, economical cost, and mechanical flexibility properties,24,

51-52, 54

and most importantly, they can be highly compatible with paper

material’s surface through simple coating treatments.61 In this report, a practical and scalable paper-based pressure sensing device design accommodating superior performance indices, such as detection sensitivity, applicable pressure range, response repeatability, fabrication convenience, and power consumption level is introduced. The filter paper substrate is first coated with poly(3,4-ethylenedioxythiophene) (PEDOT), a conductive polymer, followed by modifying its surface with silver nanoparticles (Ag NPs). The highly porous paper material provides sufficient spaces for mechanical force induced structure deformation, where conductive PEDOT covers the paper fiber surface and transforms the supporting substrate into a conductive base. Reducing power provided by PEDOT-induced Ag NPs in situ growth onto the paper substrate, which not only increases its conductivity but also enriches surface roughness while maintaining its great mechanical flexibility. Layers of this Ag NPs-PEDOT-paper composite material are integrated, assembled, and laminated into an intact sensing device by thermoplastic polypropylene (PP) polymer films. This sandwiched design provides fast responses, robust detections, sensitive measurements, broad detecting ranges, and an ultralow driving energy toward applied pressure spotting. Relying on these outperforming properties, practical applications, such as human respiration behavior monitoring, vocal testing, wrist pulse recording, and multiple body motion detections, are achieved, realizing a sensor design for human-machine interfacing that is simple, low cost, and rendering scalable process for highly sensitive and broad pressure detection range.

5



RESULTS and DISCUSSION In a practical and sensitive pressure sensing device, a few key components, i.e. conductive intermediate, deformable supporting substrate, and compact enclosing sealing are required. To achieve these demands at once, a robust approach incorporating Ag NPs-PEDOT-paper composite materials with the thermal lamination sealing protection is introduced. This strategy utilizes conductive polymers as the intermediate, which are dispersed homogeneously onto deformable porous paper fiber structures. Highly conductive Ag NPs are reduced in situ onto polymer surfaces, which greatly increase intermediate conductivity while simultaneously raising fiber structure roughness. Layers of this Ag NPs-PEDOT-paper composite material are thereafter enclosed and protected via a thermal lamination approach with PP polymer films, which provide robustness, rapidity in responses, and repeatability of the assembled devices. The fabrication process of this Ag NPs-PEDOT-paper composite material-based pressure sensing device is demonstrated in Scheme 1. First, conductive PEDOT polymer is synthesized through an oxidative polymerization process, where EDOT monomer and iron nitrate are first dissolved and mixed homogeneously in ethanol. This mixture solution is thereafter drop casted onto a 2 cm × 2 cm filter paper and dried under ambient until a black appearance presents after solvent evaporation. The paper piece is subsequently cleaned by copious amount of methanol and deionized water, vacuum dried, and emplaced into a silver nitrate solution for in situ Ag NP growth on PEDOT. Due to reduction power provided by PEDOT polymers,62 no extra reducing agent is added in this process. The product, Ag NPs-PEDOT-paper composite material, is ready to use after deionized water cleaning and vacuum drying. Layers of this Ag NPs-PEDOT-paper composite material are placed in between two thermoplastic PP films in a device assembling process, where the top and the bottom layers are individually connected to a copper foil. This sandwiched stack is afterward laminated with a heated laminating machine, which encloses

6


Page 6 of 36

Page 7 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


all the components inside one compact pouch preparing the device for further pressure sensing tests. To investigate how each treatment in the fabrication process affects the substrate morphology and confirm material modification effectiveness, this Ag NPs-PEDOT-paper composite material preparation is step-wisely studied by scanning electron microscopy (SEM). As shown in Figure 1, the paper fiber appearance after PEDOT polymerization and dispersing treatments (Figure 1E) indicates a thin polymer film coating compared to a pristine paper fiber surface (Figure 1D). The Ag NP growth process introduces an apparent nanoparticle layer covering the PEDOT-coated paper fiber (Figure 1F), while each particle size is estimated to be around 25 nm in diameter. These nanoparticle covering polymer surfaces are confirmed with energy dispersive X-ray spectrometry (EDX) analysis, and elemental studies reveal the Ag NPs integration onto PEDOT polymers (Figure S1). It is also important to note that, the porous property of paper material is maintained after both PEDOT coating and Ag NP growth steps (Figure 1A to 1C), which is crucial to preserve sufficient spaces for structure deformation in a pressure sensor design. Since the addition of Ag NPs onto PEDOT polymers in our process is expected to change physical properties of the composite material, a device thereafter assembled should present different electrical signal upon external pressure based on two factors. First, the enhanced conductive mechanism by electron tunneling process between neighboring metal nanoparticles should provide a higher sensitivity toward pressure stimulus.36, 62 Furthermore, metal nanoparticles embedded on the polymer surface can further enhance material’s roughness, which is beneficial for device sensitivity relying on pressure-induced contacting area fluctuation. As shown in Figure 1G, the initial resistance of a device increases with the stacked layer numbers, which is attributed to the innate resistive property of each composite material layer. A longer AgNO3 immersion time, differently, results in decreased resistance regardless of stacked layer quantities due to

7



more Ag NPs deposition on PEDOT. This material resistance reduction also implies lower device power consumption, which is crucial to practical sensing device fabrication. In addition to the conductive intermediate material investigation, an enclosing system, which can provide integrity for sensing devices with highly repeatable and rapid effective deformation responses, should be taken into consideration. When pressure stimulus is applied onto an enclosed system, as shown in Figure 2, its electrical resistance reduces. The degree of reduction dependents on the applied pressure. As the pressure extent increases, the number of contact points between layers of Ag NPs-PEDOT-paper composite material raises, resulting in more efficient electrical conduction routes and an overall device resistance reduction. To evaluate the performance of pressure sensors enclosed by different materials, four layers of Ag NPs-PEDOT-paper composite materials are sandwiched by PP film, 3M scotch tape, polyimide (PI) tape, or commercially available polyethylene terephthalate/ethylene-vinyl acetate (PET/EVA) film independently, and their responses to an external pressure are compared (Figure S2). In this pressure sensing operation, a constant potential is applied over the device, and a pressure-induced resistance fluctuation leads to the change of measured currents. Since an external pressure applied onto a device increases contact region (reduces gaps) between different composite material layers, entire device resistance reduces and a raised current is recorded. External pressure-induced current change in the device can therefore be continuously repeated. Owing to the inability of the overly flexible tape to properly hold the substrate in place, devices enclosed by 3M tapes and PI tapes result in lower pressure-induced current fluctuation, unstable signals, and less repeatable measurements. On the other hand, the high rigidity of the PET/EVA film causes the stacked layers to be fixed in the compressed state after pressure stimulus, and repeatable measurements cannot be obtained.

8


Page 8 of 36

Page 9 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Device sensitivity is one of the most important parameters in determining the pressure sensor performance and capability toward practical applications.16-17, 31, 63-64 In this work, the sensitivity S of a pressure sensor is defined as S = δ(ΔI/I0)/δP,16, 65 where P refers to the applied pressure, ΔI and I0 refer to the current change and initial current without the pressure applied, respectively. In our device design, stacking of multiple composite materials is employed since more available spaces between different layers should provide advanced contact region changes, and is expected to increase the overall device sensitivity. As evident in Figure 3A-3C, the relative current change ΔI/I0 of devices versus a linearly increasing pressure from 0 Pa to 120 kPa reveals rapid changes within lower pressure ranges and gradually flattens out in higher-pressured regions.16-18,

31

Interestingly, this typical

piezoresistive pressure responding behavior is found to be relevant to Ag NPs-PEDOT-paper composite material layer quantity and metallic silver deposition condition. The relative current change per kPa, i.e. curve slope in Figure 3A-3C, is defined as device sensitivity in this study. These acquired values in the range of 0-10 kPa pressure and their relationships with stack layers and Ag NP growth condition are summarized in Figure 3D. Taking the device with four layers of material stacks as an example, the observed sensitivity raises from 0.05 kPa-1 to 0.12 kPa-1 along with Ag NP growth time within 60 s. The rise in sensitivity is attributed to the increased roughness of the PEDOT-covered paper fiber surface, where a rougher interface leads to more effective contact area changes during the external pressure exposure. However, an overdosed Ag NP quantity on the PEDOT-covered paper fiber surface results in direct electron transduction through abundant connected metallic silver, and a less obvious current change occurs under the applied pressure. This phenomenon sets up a sensitivity tumble, as observed by the decreases at 90 s and 120 s of Ag NP growth time. It is also clear to see that the device sensitivity raising and declining trends along with Ag NP growth time are similar when different layers of this Ag NPs-PEDOT-paper composite

9



material are enclosed within one device. A higher device sensitivity, however, is observed along with more stacked layers, which is attributed to the greater available spaces between different layers for contact-induced deformation changes. However, it should be noted that excessive thickness from five or more layers of Ag NPs-PEDOT-paper composite materials compromises the lamination process in device assembly. Devices fabricated with four layers of composite materials prepared with 60 s of Ag NP growth, which give the highest sensitivity and reasonably low inter-device variation (3.0% RSD, N = 5), are therefore selected as the optimal parameter and employed for further experiments. To verify capabilities of this Ag NPs-PEDOT-paper composite material based pressure sensing device, properties including sensitivity in different pressure range, ohmic contact behavior, response and recovery speed, various consecutive response, and long term repeatability are examined. As demonstrated in Figure 4A, this device is capable to respond under a wide range of pressure. The obtained device sensitivities are found to be 0.119 and 0.031 kPa-1 at ranges of 0-12 and 12-40 kPa, respectively. Compared to sensors fabricated with other materials (Table S1), sensitivities obtained in this work are relatively high (e.g. 0.119 kPa-1 at the 0-12 kPa range). To characterize physical properties of the assembled device, current-voltage (I-V) curves under different pressures (0, 800, 1600, 2400, 3200, and 4000 Pa) are first studied, as shown in Figure 4B. In the range of -0.10 V to 0.10 V, linear responses in I-V curves reveal that the assembled devices obey the ohmic contact behavior, and can produce consistent signal responses under various external pressure exposures. When the applied pressure increases, the I-V slop also raises and maintains a linear relationship up to 4000 Pa, representing stable ohmic contacting behaviors of the device under different ranges of pressure testing. Evaluation of the device response and recovery speed is carried out by employing a periodic operation with consecutive press and release cycles at a constant force of 10 g. The device responses are recorded as shown in Figure 4C, where response

10


Page 10 of 36

Page 11 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(press) and recovery (release) times upon cyclic constant pressure stimulus are recorded to be 200 ms and 100 ms, respectively. We further examine the device resistance changes under a series of different applied pressures (2400, 4800, 7200, and 9600 Pa), as demonstrated in Figure 4D. Aside from recording very reproducible signals under a rapid repeating constant pressure stimulus, highly stable corresponding responses are observed with increasing pressure boosts on this sensing device. Such behavior can also be observed when a higher pressure up to 400 kPa is employed, as shown in Figure S3. More importantly, this device is very durable and can produce consistent signals under numbers of operations. This can be observed in Figure 4E and 4F, where 2000 cycles of 2 kPa and 200 kPa stimulus onto the device only induce minor signal fluctuation in responses. We therefore concluded that current device is highly durable and reliable for detecting pressure at different ranges, and these advantages are attributed to the integration of composite materials with robust and compact sandwich lamination enclosing approach used in this design. Based on the superior performance of this device design, various pressure-related human motions are tested, such as exhalation, vocal vibrations of the throat, and wrist pulses. A 2 cm × 2 cm patch of pressure sensing device fabricated by this approach is utilized for illustration, and the motion-induced signal alteration versus stimulus duration is recorded. As shown in Figure 5A, a device is placed in front of the tester’s mouth with a constant and repetitive exhalation employment. This motion generates a consecutive gas flow and results in obvious gas flow dependent signal fluctuation. In a vocal vibration testing, this sensing device is attached onto a tester’s throat to monitor the vocal cords vibration induced pressure stimulus difference during the speech. As demonstrated in Figure 5B, a sensitive and obvious pattern is observed when the tester speaks the letters “N”, “T”, and “U” repeatedly. This sensitive and effective voice recognition approach is promising to help people with damaged vocal cords or pronunciation obstacles by speech ability recovery.37 Another important application

11



of this pressure sensor design is measurements of a person’s wrist pulse, which can be achieved by placing the device onto a tester’s wrist, as shown in Figure 5C. Consistent and repeating responses recorded under this test point to robust in situ physiological detection, and importantly, a typical radial arterial pulse waveform representing systolic peak (P1), late systolic peak (P2), and diastolic peak (P3) can also be observed (Figure 5D).66 These results indicate sensitive and precise pulse detection via this approach, and are very promising for practical physiological diagnosis. It is important to note that the size of this pressure sensor can also be adjusted according to needs by changing in the dimension of the paper pieces during device assembly, which can widely broaden their practical application in different fields. For example, a smaller-sized device fabricated with a 1 cm × 1 cm paper piece is attached to a tester’s cheek (Figure 6A) or finger (Figure 6B) for facial and finger motion monitoring. The obvious bend and release motion cycles are both clearly observed, and their corresponding signals are also highly repeatable regardless of a smaller sensor dimension. Furthermore, this tiny device can also be attached under a tester’s nose to monitor the human body respiration rate. As evident from Figure 6C, the gas flow from the tester’s nose reveals a person’s breathing behavior, where normal and deep breath differentiate with signal response amplitude while the respiration cycle frequency varies before and after exercise at 14 Hz and 60 Hz, respectively. Conversely, larger-sized pressure sensors fabricated by this approach can also provide precise and consistent human motion detection. As demonstrated in Figure 7A and 7B, 2 cm × 4 cm filter papers are used as base substrates, and corresponding fabricated devices are used to detect wider motions such as hand posture or knee bending. The bend and release cycles are recorded by these sensors attached onto tester’s wrist or knee, representing their promising application for diverse human motion detection. In addition, the consistent response of a

12


Page 12 of 36

Page 13 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


device over 75 consecutive knee-bending motion indicates the high stability of paper substrates protected by this lamination approach (Figure S4). With the broad sensing capability and fabrication flexibility provided by this design, we further realize a functional device accomplished by human-machine interface entanglement. Multiple 2 cm × 4 cm paper material based pressure sensors are serially assembled into a musical keyboard, as shown in Figure 7C, and each sensor is independently connected to a mutual data acquisition equipment. A constant overall current is applied across the whole keyboard device, and the acquired resistance values reported from each sensor are analyzed via a LabVIEW program. When an external pressure (finger touch) is applied onto an individual sensor, the fluctuation of detected resistance value is recorded where a decrease of sensor resistance is expected, as shown in Figure 7D. In a practical musical keyboard design, each specific sensor is designated with a frequency key which can produce a specific note. Besides, a sensor resistance change value threshold is preset to report an effective external pressure stimulus, allowing correct computer recognition of finger touch in the signal feedback process. Integration of these two parameters enables a tester to play the keyboard and produce musical rhythm, as shown in Figure 7D and Video 1. It should be noted that this musical keyboard can not only detect the presence of external pressure, but can also reflect the magnitude of an applied stimulus along with duration to correspond different volume and length of the sound, respectively (Video 2). Upon this approach, a complete musical scale can be generated on our keyboard and a representative song is played as shown in Video 3.

CONCLUSIONS Through a simple, low-cost, and scalable approach based on Ag NPs-PEDOT-paper composite materials and thermal lamination enclosing, we developed a flexible and highly sensitivity pressure sensing device with broad detection ranges. Porous and flexible paper

13



material is used as a solid support where its entangled fibers are coated by conductive polymer PEDOT. The conductive polymer coating provides great conductivity to cellulous fibers, and renders a reductant free capability to transform silver ions into Ag NPs decorating on PEDOT surfaces. Incorporation of Ag NPs onto PEDOT not only enhances the material conductivity, but also raises polymer surface roughness. These two factors heavily affect the performance of the pressure sensing device through the Ag NPs-PEDOT-paper composite material, where the reduced material resistance limits power consumption and the raised surface roughness increases the sensitivity of the functional device. In addition to the advanced conductive intermediate fabrication, observed sensing device robustness and outstanding performance lie in advantageous thermal lamination provided compact enclosing. This approach supplies a confined detecting region maintaining the deformable supporting substrate behavior and reduces outside environment interferences. Pressure sensors designed with this strategy exhibit a broad detectable pressure range, and carry high sensitivity of 0.119 kPa-1 (at the 0-12 kPa range) with very stable responses over 2000 cycles of tests. Although the device response and recovery speeds are relatively high, current design can still provide the desired human motion detection effectively. Further improvements on these works are worth continuing. For example, efforts on device integration condition optimization and material composition adjustments should help to achieve higher sensitivity and faster response in this approach. These excellent sensing performances are applied to integrating several practical devices for various human-motion detection, e.g., respiration detection, voice recognition, wrist pulse detection, and human body movements. We envision using this highly sensitive and size-tunable sensor in real-time motion monitoring as a convenient method for fabrication of point-of-care wearable electronics, which is especially suitable for patients suffering from heart attack, asthma, or other diseases. Our successful demonstration of human-machine interface connection by voice recognition and piano

14


Page 14 of 36

Page 15 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


keyboard musical translation opens a two-way dual channel for in situ human behavior-digital signal communication and artificial intelligence programming.

15



Scheme 1. (A) Fabrication process of the pressure sensing device based on the Ag NPs-PEDOT-paper composite material. (B) Photo images of the Ag NPs-PEDOT-paper composite material (top) and an assembled pressure sensing device (bottom). The scale bars are 1 cm.

16


Page 16 of 36

Page 17 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 1. SEM images of (A) Bared filter paper, (B) PEDOT-paper composite, (C) Ag NPs-PEDOT-paper composite. Insets: corresponding material photo graphs. (D), (E), (F) are high magnification images of (A), (B), (C), respectively. Yellow and red scale bars are 2 μm and 200 nm, respectively. (G) Resistance alteration of assembled Ag NPs-PEDOT-paper devices with different composite material AgNO3 immersion time and layer quantity.

17



Figure 2. Illustration of the stacked Ag NPs-PEDOT-paper composite material layer resistance reduction mechanism under increased external pressure. As the applied pressure increases, the number of contact points within a composite material layer and between different layers rises, leading to an overall device resistance reduction.

18


Page 18 of 36

Page 19 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. Change of Ag NPs-PEDOT-paper device measured current upon introduced external pressure when (A) two, (B) three, and (C) four layers of composite materials are assembled within a device. (D) Alteration of device sensitivity within 0-10 kPa pressure range when using composite materials prepared with different AgNO3 immersion time. A similar trend is observed when the device is assembled with different composite material quantity.

19



Figure 4. Properties of an assembled Ag NPs-PEDOT-paper device using four layers of composite materials with 60 s of Ag NP growth. (A) Current responses against the applied pressure. The inset shows the device response for 0-40 kPa; S1 and S2 refer to the sensitivity at the ranges of 0-12 kPa and 12-40 kPa, respectively. (B) Current-voltage curves under different applied pressures. (C) Response and recovery time of the device when applied with a repetitive constant 10 g force. (D) Consecutive response tests under different applied pressures (2400 Pa, 4800 Pa, 7200 Pa, 9600 Pa). (E) Long term response repeatability test with 2000 cycles of 2 kPa applied pressure. (F) Long term response repeatability test with 2000 cycles of 200 kPa applied pressure.

20


Page 20 of 36

Page 21 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 5. Representative practical applications of a sensing device using 2 cm × 2 cm size Ag NPs-PEDOT-paper composite material as the base. (A) Exhalation detection of a continuous periodic blowing toward the device. (B) Vocal test with repetitive pronunciation of the letters “N”, “T”, and “U”. (C) Wrist pulse detection on a healthy person. (D) The enlarged signal collected in part C showing three characteristic portions in a set of response.

21



Figure 6. Representative practical applications of a sensing device using 1 cm × 1 cm size Ag NPs-PEDOT-paper composite material as the base. (A) Repetitive human facial motion detection. (B) Repetitive finger bending and releasing detection. (C) Respiration behavior detection of a healthy person taking normal breathing (black), deep breathing (red), and breathing after exercise (blue).

22


Page 22 of 36

Page 23 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 7. Representative practical applications of a sensing device using 2 cm × 4 cm size Ag NPs-PEDOT-paper composite material as the base. (A) Repetitive human wrist bending and releasing detection. (B) Repetitive human knee bending and releasing detection. (C) Photo graphs of the integrated sensing device, which can be fully stacked, stretched, and extended as a piano keyboard. (D) Representative five tones tested in this human-machine interface entanglement setup. Channel 1-5 refer to individual signals collected from five connected but separately recording sensors.

23



EXPERIMENTAL SECTION Materials 3,4-ethylenedioxythiophene (EDOT) (Tokyo Chemical Industry, Tokyo, Japan), iron(III) nitrate nonahydrate (Showa Chemicals, Tokyo, Japan), silver nitrate (Sigma-Aldrich, St. Louis, MO, USA), ethanol (Echo Chemical, Taipei, Taiwan) were purchased and used without further purification unless otherwise stated. Deionized water (18.2 MΩ∙cm) from the ELGA PURELAB classic system (Taipei, Taiwan) was used throughout the experiments. Filter paper was purchased from ADVANTEC (Tokyo, Japan) and used as such by cutting into a 2 cm × 2 cm dimension. Polypropylene film (POMEI, Kaohsiung, Taiwan), copper foil (Gredmann Group, Taipei, Taiwan), and silver paste (Askmi Industries Ltd., New Taipei City, Taiwan) were purchased and used as received.

Characterization and Measurements. A digital camera (Leica D-LUX 6, Wetzlar, Germany) was used throughout the experiments for photograph capture. A TCC-6000 laminating machine (Tah Hsin Industrial Corp., Taichung, Taiwan) was used for the sensing device lamination. The scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX) data were collected by a field emission SEM microscope (Hitachi S-4800, Tokyo, Japan). A sourcemeter (Keithley 2400, Beaverton, OR, USA) was used as the power source and the electrical signal collector in device property study experiments. The external pressure was applied to the center region of the device and controlled by a universal testing machine (Shimadzu EZ-X, Tokyo, Japan).

Sensing Device Fabrication The conductive PEDOT polymer was synthesized by an oxidative polymerization process,62 where 5.3 mmol of EDOT monomer and 4.7 mmol of Fe(NO3)3∙9H2O were

24


Page 24 of 36

Page 25 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


dissolved in 7.56 mL of ethanol and stirred continuously at room temperature for 20 min. 180 μL of this mixture solution was then drop casted on one side of a 2 cm × 2 cm filter paper piece, and the process was repeated one more time on the back side. This PEDOT-coated paper was then left in ambient atmosphere for 12 h, and the color of paper changed to black after complete solvent evaporation. Copious amount of methanol followed by water was then used to remove unreacted reactants and residues on this PEDOT-coated paper and the substrate was vacuumed for 3 h. This dried PEDOT-modified filter paper was thereafter immersed into 20 mM of AgNO3 aqueous solution to form Ag NPs-PEDOT-paper composites. This process does not require additional reductants due to reducing powers provided by PEDOT polymer coated on the filter paper fiber.62 After Ag NP growth, the paper substrate was removed from the AgNO3 solution, washed with copious of deionized water, and dried under vacuum for 3 h. In the device assembling process, layers of Ag NPs-PEDOT-paper composite materials were stacked and enclosed with different methods for comparison, including PP film lamination, 3M scotch tape enclosing, and PI tape sealing, while heat lamination yields the best device stability and detection sensitivity. In the heat lamination process, the top and bottom layers of Ag NPs-PEDOT-paper composite materials were individually connected to a copper foil piece wiring by silver paste, and the whole stack was laminated together with two PP films at 100 ℃ under a constant speed of 0.6 cm/sec by a laminating machine. Schematic representation of the device fabrication process and photographs of an assembled pressure sensing device is presented in Scheme 1.

25



ASSOCIATED CONTENT Supporting Information. The supplementary information for manuscript “Multilayered Ag NPs-PEDOT-Paper Composite Device for Human-Machine Interfacing” includes the following: Figure S1. SEM image and corresponding EDX analysis of the Ag NPs-PEDOT-paper composite material. Figure S2. Responses of the Ag NPs-PEDOT-paper composite material based pressure sensing device enclosed with different materials under repetitive constant pressure testing. Figure S3. Consecutive response tests on a device under different applied pressures (2 kPa, 10 kPa, 200 kPa, and 400 kPa). Figure S4. Device performance under 75 consecutive knee-bending test cycles. Table S1. Comparison between literature-reported piezoresistive devices made with various substrates and the current work on detectable pressure ranges and corresponding sensitivities. Representative musical pieces: Video 1-3

AUTHOR INFORMATION Corresponding Author *To whom correspondence should be addressed: [email protected]. Author Contributions †These authors contributed equally. Notes

26


Page 26 of 36

Page 27 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


There are no conflicts to declare.

ACKNOWLEDGMENT This work was supported by the Taiwan Ministry of Science and Technology (MOST 106-2113-M-002-015-MY2). The authors would like to thank Prof. Yit-Tsong Chen at National Taiwan University for instrument support and helpful discussions.

REFERENCE 1.

Kim, D. H.; Kim, Y. S.; Wu, J.; Liu, Z.; Song, J.; Kim, H. S.; Huang, Y. Y.; Hwang, K.

C.; Rogers, J. A., Ultrathin Silicon Circuits with Strain‐Isolation Layers and Mesh Layouts for High‐Performance Electronics on Fabric, Vinyl, Leather, and Paper. Adv. Mater. 2009, 21, 3703-3707. 2.

Yamada, T.; Hayamizu, Y.; Yamamoto, Y.; Yomogida, Y.; Izadi-Najafabadi, A.; Futaba,

D. N.; Hata, K., A Stretchable Carbon Nanotube Strain Sensor for Human-Motion Detection. Nat. Nanotechnol. 2011, 6, 296. 3.

Levi, A.; Piovanelli, M.; Furlan, S.; Mazzolai, B.; Beccai, L., Soft, Transparent,

Electronic Skin for Distributed and Multiple Pressure Sensing. Sensors 2013, 13, 6578-6604. 4.

Pang, C.; Lee, C.; Suh, K. Y., Recent Advances in Flexible Sensors for Wearable and

Implantable Devices. J. Appl. Polym. Sci. 2013, 130, 1429-1441. 5.

Wang, C.; Hwang, D.; Yu, Z.; Takei, K.; Park, J.; Chen, T.; Ma, B.; Javey, A.,

User-Interactive Electronic Skin for Instantaneous Pressure Visualization. Nat. Mater. 2013, 12, 899. 6.

Wang, X.; Dong, L.; Zhang, H.; Yu, R.; Pan, C.; Wang, Z. L., Recent Progress in

Electronic Skin. Adv. Sci. 2015, 2, 1500169. 27



7.

Roche, E. T.; Wohlfarth, R.; Overvelde, J. T.; Vasilyev, N. V.; Pigula, F. A.; Mooney, D.

J.; Bertoldi, K.; Walsh, C. J., Actuators: A Bioinspired Soft Actuated Material. Adv. Mater. 2014, 26, 1200. 8.

Polygerinos, P.; Wang, Z.; Galloway, K. C.; Wood, R. J.; Walsh, C. J., Soft Robotic

Glove for Combined Assistance and At-Home Rehabilitation. Rob. Auton. Syst. 2015, 73, 135-143. 9.

Jeong, J. W.; Yeo, W. H.; Akhtar, A.; Norton, J. J.; Kwack, Y. J.; Li, S.; Jung, S. Y.; Su,

Y.; Lee, W.; Xia, J., Epidermal Electronics: Materials and Optimized Designs for Human-Machine Interfaces via Epidermal Electronics. Adv. Mater. 2013, 25, 6839-6846. 10. Yang, W.; Chen, J.; Wen, X.; Jing, Q.; Yang, J.; Su, Y.; Zhu, G.; Wu, W.; Wang, Z. L., Triboelectrification Based Motion Sensor for Human-Machine Interfacing. ACS Appl. Mater. Interfaces 2014, 6, 7479-7484. 11. Roh, E.; Hwang, B.-U.; Kim, D.; Kim, B.-Y.; Lee, N.-E., Stretchable, Transparent, Ultrasensitive, and Patchable Strain Sensor for Human-Machine Interfaces Comprising a Nanohybrid of Carbon Nanotubes and Conductive Elastomers. ACS Nano 2015, 9, 6252-6261. 12. Dong, W.; Xiao, L.; Hu, W.; Zhu, C.; Huang, Y.; Yin, Z., Wearable Human-Machine Interface Based on PVDF Piezoelectric Sensor. Trans. Inst. Meas. Control 2017, 39, 398-403. 13. Zhang, Y.; Hu, Y.; Zhu, P.; Han, F.; Zhu, Y.; Sun, R.; Wong, C.-P., Flexible and Highly Sensitive Pressure Sensor Based on Microdome-Patterned PDMS Forming with Assistance of Colloid Self-Assembly and Replica Technique for Wearable Electronics. ACS Appl. Mater. Interfaces 2017, 9, 35968-35976. 14. Park, H.; Jeong, Y. R.; Yun, J.; Hong, S. Y.; Jin, S.; Lee, S.-J.; Zi, G.; Ha, J. S., Stretchable Array of Highly Sensitive Pressure Sensors Consisting of Polyaniline Nanofibers

28


Page 28 of 36

Page 29 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


and Au-Coated Polydimethylsiloxane Micropillars. ACS Nano 2015, 9, 9974-9985. 15. Haniff, M. A. S. M.; Hafiz, S. M.; Wahid, K. A. A.; Endut, Z.; Lee, H. W.; Bien, D. C.; Azid, I. A.; Abdullah, M. Z.; Huang, N. M.; Rahman, S. A., Piezoresistive Effects in Controllable Defective HFTCVD Graphene-Based Flexible Pressure Sensor. Sci. Rep. 2015, 5, 14751. 16. Dong, X.-C.; Ge, G.; Cai, Y.; Dong, Q.; Zhang, Y.; Shao, J.; Huang, W., Flexible Pressure Sensor Based on rGO/Polyaniline Wrapped Sponge with Tunable Sensitivity for Human Motions Detection. Nanoscale 2018, 10, 10033-10040. 17. Yao, H. B.; Ge, J.; Wang, C. F.; Wang, X.; Hu, W.; Zheng, Z. J.; Ni, Y.; Yu, S. H., A Flexible and Highly Pressure‐Sensitive Graphene-Polyurethane Sponge Based on Fractured Microstructure Design. Adv. Mater. 2013, 25, 6692-6698. 18. Tai, Y.; Lubineau, G., Double‐Twisted Conductive Smart Threads Comprising a Homogeneously

and

a

Gradient‐Coated

Thread

for

Multidimensional

Flexible

Pressure-Sensing Devices. Adv. Funct. Mater. 2016, 26, 4078-4084. 19. Mannsfeld, S. C.; Tee, B. C.; Stoltenberg, R. M.; Chen, C. V. H.; Barman, S.; Muir, B. V.; Sokolov, A. N.; Reese, C.; Bao, Z., Highly Sensitive Flexible Pressure Sensors with Microstructured Rubber Dielectric Layers. Nat. Mater. 2010, 9, 859. 20. Zhu, B.; Niu, Z.; Wang, H.; Leow, W. R.; Wang, H.; Li, Y.; Zheng, L.; Wei, J.; Huo, F.; Chen, X., Microstructured Graphene Arrays for Highly Sensitive Flexible Tactile Sensors. Small 2014, 10, 3625-3631. 21. Boutry, C. M.; Nguyen, A.; Lawal, Q. O.; Chortos, A.; Rondeau‐Gagné, S.; Bao, Z., A Sensitive and Biodegradable Pressure Sensor Array for Cardiovascular Monitoring. Adv. Mater. 2015, 27, 6954-6961. 22. Pang, C.; Koo, J. H.; Nguyen, A.; Caves, J. M.; Kim, M. G.; Chortos, A.; Kim, K.; Wang, P. J.; Tok, J. B. H.; Bao, Z., Highly Skin‐Conformal Microhairy Sensor for Pulse

29



Signal Amplification. Adv. Mater. 2015, 27, 634-640. 23. Pan, C.; Dong, L.; Zhu, G.; Niu, S.; Yu, R.; Yang, Q.; Liu, Y.; Wang, Z. L., High-Resolution Electroluminescent Imaging of Pressure Distribution using a Piezoelectric Nanowire LED Array. Nat. Photonics 2013, 7, 752. 24. Persano, L.; Dagdeviren, C.; Su, Y.; Zhang, Y.; Girardo, S.; Pisignano, D.; Huang, Y.; Rogers, J. A., High Performance Piezoelectric Devices Based on Aligned Arrays of Nanofibers of Poly(vinylidenefluoride-co-trifluoroethylene). Nat. Commun. 2013, 4, 1633. 25. Chun, J.; Lee, K. Y.; Kang, C. Y.; Kim, M. W.; Kim, S. W.; Baik, J. M., Embossed Hollow Hemisphere‐Based Piezoelectric Nanogenerator and Highly Responsive Pressure Sensor. Adv. Funct. Mater. 2014, 24, 2038-2043. 26. Lee, J. H.; Yoon, H. J.; Kim, T. Y.; Gupta, M. K.; Lee, J. H.; Seung, W.; Ryu, H.; Kim, S. W., Micropatterned P(VDF‐TrFE) Film‐Based Piezoelectric Nanogenerators for Highly Sensitive Self‐Powered Pressure Sensors. Adv. Funct. Mater. 2015, 25, 3203-3209. 27. Lee, J.; Kwon, H.; Seo, J.; Shin, S.; Koo, J. H.; Pang, C.; Son, S.; Kim, J. H.; Jang, Y. H.; Kim, D. E., Conductive Fiber‐Based Ultrasensitive Textile Pressure Sensor for Wearable Electronics. Adv. Mater. 2015, 27, 2433-2439. 28. Davidovikj, D.; Scheepers, P. H.; van der Zant, H. S.; Steeneken, P. G., Static Capacitive Pressure Sensing using a Single Graphene Drum. ACS Appl. Mater. Interfaces 2017, 9, 43205-43210. 29. Lei, Z.; Wang, Q.; Sun, S.; Zhu, W.; Wu, P., A Bioinspired Mineral Hydrogel as a Self-Healable, Mechanically Adaptable Ionic Skin for Highly Sensitive Pressure Sensing. Adv. Mater. 2017, 29, 1700321. 30. Shuai, X.; Zhu, P.; Zeng, W.; Hu, Y.; Liang, X.; Zhang, Y.; Sun, R.; Wong, C.-P., Highly Sensitive Flexible Pressure Sensor Based on Silver Nanowires-Embedded Polydimethylsiloxane Electrode with Microarray Structure. ACS Appl. Mater. Interfaces 2017,

30


Page 30 of 36

Page 31 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


26314-26324. 31. He, Z.; Chen, W.; Liang, B.; Liu, C.; Yang, L.; Lu, D.; Mo, Z.; Zhu, H.; Tang, Z.; Gui, X., A Capacitive Pressure Sensor with High Sensitivity and Fast Response to Dynamic Interaction Based on Graphene and Porous Nylon Networks. ACS Appl. Mater. Interfaces 2018, 10, 12816-12823. 32. Yu, L.; Yeo, J. C.; Soon, R. H.; Yeo, T.; Lee, H. H.; Lim, C. T., Highly Stretchable, Weavable and Washable Piezoresistive Microfiber Sensor. ACS Appl. Mater. Interfaces 2018, 10, 12773-12780. 33. Huang, J.; Wang, J.; Yang, Z.; Yang, S., High-Performance Graphene Sponges Reinforced with Polyimide for Room-Temperature Piezoresistive Sensing. ACS Appl. Mater. Interfaces 2018, 10, 8180-8189. 34. Zhan, Z.; Lin, R.; Tran, V.-T.; An, J.; Wei, Y.; Du, H.; Tran, T.; Lu, W., Paper/Carbon Nanotube-Based Wearable Pressure Sensor for Physiological Signal Acquisition and Soft Robotic Skin. ACS Appl. Mater. Interfaces 2017, 9, 37921-37928. 35. Tao, L.-Q.; Zhang, K.-N.; Tian, H.; Liu, Y.; Wang, D.-Y.; Chen, Y.-Q.; Yang, Y.; Ren, T.-L., Graphene-Paper Pressure Sensor for Detecting Human Motions. ACS Nano 2017, 11, 8790-8795. 36. Zhang, H.; Liu, N.; Shi, Y.; Liu, W.; Yue, Y.; Wang, S.; Ma, Y.; Wen, L.; Li, L.; Long, F., Piezoresistive Sensor with High Elasticity Based on 3D Hybrid Network of Sponge@ CNTs@ Ag NPs. ACS Appl. Mater. Interfaces 2016, 8, 22374-22381. 37. Wang, X.; Gu, Y.; Xiong, Z.; Cui, Z.; Zhang, T., Silk‐Molded Flexible, Ultrasensitive, and Highly Stable Electronic Skin for Monitoring Human Physiological Signals. Adv. Mater. 2014, 26, 1336-1342. 38. Chang, H.; Kim, S.; Jin, S.; Lee, S.-W.; Yang, G.-T.; Lee, K.-Y.; Yi, H., Ultrasensitive and Highly Stable Resistive Pressure Sensors with Biomaterial-Incorporated Interfacial

31



Layers for Wearable Health-Monitoring and Human-Machine Interfaces. ACS Appl. Mater. Interfaces 2017, 1067-1076. 39. Jung, M.; Kim, K.; Kim, B.; Cheong, H.; Shin, K.; Kwon, O.-S.; Park, J.-J.; Jeon, S., Paper-Based Bimodal Sensor for Electronic Skin Applications. ACS Appl. Mater. Interfaces 2017, 9, 26974-26982. 40. Qi, K.; He, J.; Wang, H.; Zhou, Y.; You, X.; Nan, N.; Shao, W.; Wang, L.; Ding, B.; Cui, S., A Highly Stretchable Nanofiber-Based Electronic Skin with Pressure-, Strain-, and Flexion-Sensitive Properties for Health and Motion Monitoring. ACS Appl. Mater. Interfaces 2017, 42951-42960. 41. Hsieh, H.-H.; Hsu, F.-C.; Chen, Y.-F., Energetically Autonomous, Wearable, and Multifunctional Sensor. ACS Sens. 2018, 3, 113-120. 42. Wei, S.; Qu, G.; Luo, G.; Huang, Y.; Zhang, H.; Zhou, X.; Wang, L.; Liu, Z.; Kong, T., Scalable and Automated Fabrication of Conductive Tough-Hydrogel Microfibers with Ultrastretchability, 3D Printability, and Stress Sensitivity. ACS Appl. Mater. Interfaces 2018, 10, 11204-11212. 43. Chen, L.; Chen, G.; Lu, L., Piezoresistive Behavior Study on Finger‐Sensing Silicone Rubber/Graphite Nanosheet Nanocomposites. Adv. Funct. Mater. 2007, 17, 898-904. 44. Lou, Z.; Chen, S.; Wang, L.; Jiang, K.; Shen, G., An Ultra-Sensitive and Rapid Response Speed Graphene Pressure Sensors for Electronic Skin and Health Monitoring. Nano Energy 2016, 23, 7-14. 45. Pang, Y.; Tian, H.; Tao, L.; Li, Y.; Wang, X.; Deng, N.; Yang, Y.; Ren, T.-L., Flexible, Highly Sensitive, and Wearable Pressure and Strain Sensors with Graphene Porous Network Structure. ACS Appl. Mater. Interfaces 2016, 8, 26458-26462. 46. Song, X.; Sun, T.; Yang, J.; Yu, L.; Wei, D.; Fang, L.; Lu, B.; Du, C.; Wei, D., Direct Growth of Graphene Films on 3D Grating Structural Quartz Substrates for High-Performance

32


Page 32 of 36

Page 33 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Pressure-Sensitive Sensors. ACS Appl. Mater. Interfaces 2016, 8, 16869-16875. 47. Gong, S.; Schwalb, W.; Wang, Y.; Chen, Y.; Tang, Y.; Si, J.; Shirinzadeh, B.; Cheng, W., A Wearable and Highly Sensitive Pressure Sensor with Ultrathin Gold Nanowires. Nat. Commun. 2014, 5, 3132. 48. Wei, Y.; Chen, S.; Dong, X.; Lin, Y.; Liu, L., Flexible Piezoresistive Sensors Based on “Dynamic Bridging Effect” of Silver Nanowires Toward Graphene. Carbon 2017, 113, 395-403. 49. Yao, S.; Myers, A.; Malhotra, A.; Lin, F.; Bozkurt, A.; Muth, J. F.; Zhu, Y., A Wearable Hydration Sensor with Conformal Nanowire Electrodes. Adv. Healthcare Mater. 2017, 6, 1601159. 50. Tang, Y.; Gong, S.; Chen, Y.; Yap, L. W.; Cheng, W., Manufacturable Conducting Rubber Ambers and Stretchable Conductors from Copper Nanowire Aerogel Monoliths. ACS Nano 2014, 8, 5707-5714. 51. Ai, Y.; Lou, Z.; Chen, S.; Chen, D.; Wang, Z. M.; Jiang, K.; Shen, G., All rGO-on-PVDF-Nanofibers Based Self-Powered Electronic Skins. Nano Energy 2017, 35, 121-127. 52. Eom, J.; Jaisutti, R.; Lee, H.; Lee, W.; Heo, J.-S.; Lee, J.-Y.; Park, S. K.; Kim, Y.-H., Highly Sensitive Textile Strain Sensors and Wireless User-Interface Devices using All-Polymeric Conducting Fibers. ACS Appl. Mater. Interfaces 2017, 9, 10190-10197. 53. Choong, C. L.; Shim, M. B.; Lee, B. S.; Jeon, S.; Ko, D. S.; Kang, T. H.; Bae, J.; Lee, S. H.; Byun, K. E.; Im, J., Highly Stretchable Resistive Pressure Sensors using a Conductive Elastomeric Composite on a Micropyramid Array. Adv. Mater. 2014, 26, 3451-3458. 54. Ding, Y.; Yang, J.; Tolle, C.; Zhu, Z., Flexible and Compressible PEDOT: PSS@ Melamine Conductive Sponge Prepared via One-Step Dip Coating as Piezoresistive Pressure Sensor for Human Motion Detection. ACS Appl. Mater. Interfaces 2018, 10, 16077-16086.

33



55. Leijonmarck, S.; Cornell, A.; Lindbergh, G.; Wågberg, L., Single-Paper Flexible Li-Ion Battery Cells Through a Paper-Making Process Based on Nano-Fibrillated Cellulose. J. Mater. Chem. A 2013, 1, 4671-4677. 56. Nguyen, T. H.; Fraiwan, A.; Choi, S., Paper-Based Batteries: A Review. Biosens. Bioelectron. 2014, 54, 640-649. 57. Kurra, N.; Dutta, D.; Kulkarni, G. U., Field Effect Transistors and RC Filters from Pencil-Trace on Paper. Phys. Chem. Chem. Phys. 2013, 15, 8367-8372. 58. Wu, H.; Chiang, S. W.; Lin, W.; Yang, C.; Li, Z.; Liu, J.; Cui, X.; Kang, F.; Wong, C. P., Towards Practical Application of Paper Based Printed Circuits: Capillarity Effectively Enhances Conductivity of the Thermoplastic Electrically Conductive Adhesives. Sci. Rep. 2014, 4, 6275. 59. Zhong, Q.; Zhong, J.; Cheng, X.; Yao, X.; Wang, B.; Li, W.; Wu, N.; Liu, K.; Hu, B.; Zhou, J., Paper‐Based Active Tactile Sensor Array. Adv. Mater. 2015, 27, 7130-7136. 60. Liana, D. D.; Raguse, B.; Gooding, J. J.; Chow, E., An Integrated Paper‐Based Readout System and Piezoresistive Pressure Sensor for Measuring Bandage Compression. Adv. Mater. Technol. 2016, 1, 1600143. 61. Kawashima, H.; Shinotsuka, M.; Nakano, M.; Goto, H., Fabrication of Conductive Paper Coated with PEDOT: Preparation and Characterization. J. Coat. Technol. Res. 2012, 9, 467-474. 62. Park, E.; seok Kwon, O.; joo Park, S.; seop Lee, J.; You, S.; Jang, J., One-Pot Synthesis of Silver Nanoparticles Decorated Poly(3,4-ethylenedioxythiophene) Nanotubes for Chemical Sensor Application. J. Mater. Chem. 2012, 22, 1521-1526. 63. Gao, Y. J.; Ota, H.; Schaler, E. W.; Chen, K.; Zhao, A.; Gao, W.; Fahad, H. M.; Leng, Y. G.; Zheng, A. Z.; Xiong, F. R.; Zhang, C. C.; Tai, L. C.; Zhao, P. D.; Fearing, R. S.; Javey, A., Wearable Microfluidic Diaphragm Pressure Sensor for Health and Tactile Touch

34


Page 34 of 36

Page 35 of 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Monitoring. Adv. Mater. 2017, 29, 1701985. 64. Wu, X. Z.; Liu, X. H.; Wang, J. Q.; Huang, J. X.; Yang, S. R., Reducing Structural Defects and Oxygen-Containing Functional Groups in GO-Hybridized CNTs Aerogels: Simultaneously Improve the Electrical and Mechanical Properties to Enhance Pressure Sensitivity. ACS Appl. Mater. Interfaces 2018, 10, 39009-39017. 65. Park, H.; Kim, J. W.; Hong, S. Y.; Lee, G.; Kim, D. S.; Oh, J. H.; Jin, S. W.; Jeong, Y. R.; Oh, S. Y.; Yun, J. Y.; Ha, J. S., Microporous Polypyrrole-Coated Graphene Foam for High-Performance Multifunctional Sensors and Flexible Supercapacitors. Adv. Funct. Mater. 2018, 28, 1707013. 66. Filipovsky, J.; Svobodova, V.; Pecen, L., Reproducibility of Radial Pulse Wave Analysis in Healthy Subjects. J. Hypertens. 2000, 18, 1033-1040.

35



Table of Contents

36


Page 36 of 36

Multilayered Ag NPs-PEDOT-Paper Composite Device for Human

Recommend Documents