Screen printable flexible conductive nanocomposite polymer with applications to wearable sensors

Abstract

We have developed a conductive nanocomposite polymer that possesses both good conductivity and flexibility, and screen printed it onto fabric to realize wearable flexible electrodes and electronic routing. The conductive polymer consists of dispersed silver nanoparticles (90~210nm) in a screen printable plastisol polymer. The conductive polymer is conductive for weight-percentages above approximately 61 wt-% of Ag nanoparticles, and has a resistivity of 2.1210 -6 ohm·m at 70 wt-% of Ag nanoparticles. To test the screen printed conductive polymer's flexibility and its effect on conductivity, we measured the resistivity of the Ag-doped composite polymer at different bending angles (-90˚ ~ 90˚) with a 10˚ step angle at different wt-% of silver particles, and compared the results. We also tested washability of the screen printed conductive polymer as applied to fabric for long-term use in wearable sensors systems. We also used the screen printed Ag composite polymer to realize an example wearable system. Flexible wearable dry electrocardiogram (ECG) electrodes were developed and ECG signal was measured via the electrodes. The sensing ECG electrodes (3mm diameter circle) were chloridized to form Ag/AgCl electrodes. We measured an ECG signal using a simple right-leg driven ECG circuit and observed normal ECG signals even without application of electrolyte gel.

Editors' Choice—Development of Screen-Printed Flexible Multi-Level Microfluidic Devices with Integrated Conductive Nanocomposite Polymer Electrodes on Textiles

“…We use 70 wt-% of Ag particles to prepare the Ag C-NCP in a similar manner to what we have reported previously. 18 The adhesion between the bottom layer and C-NCP electrodes is very strong (as tested via tape test using techniques similar to other researchers 20 ), likely because the same plastisol ink forms the base polymer for each structure. Commercial Ag epoxy is next screen printed to pattern Ag epoxy electrodes, electrical routing, and contact pads (Figure 10b).…”

“…Previously, we developed screen printable Ag C-NCP electrodes, chloridized its surface to form a AgCl surface, and employed it for measuring heart signals using Ag/AgCl electrodes fabricated on clothing. 18 As previously shown, normally non-conductive plastisol ink can be rendered conductive by mixing conductive Ag nanoparticles (90-210 nm, 99% purity from NanoAmor), resulting in a resistivity of 2.12 × 10 −6 •m at 70 wt-% of Ag particles. This Ag C-NCP is now demonstrated for electrodes and electrical routing in an active microfluidic device on a textile substrate.…”

“…16,17 We have also presented a conference paper employing plastisol-based C-NCP for electrocardiogram (ECG) electrodes for monitoring heart signals. 18 We now present here for the first time multiple layers of plastisol-based microfluidic channels and plastisol-based C-NCPs that are integrated together for wearable microfluidic devices and systems on the same textile substrate.…”

“…The sensor consists of a microfluidic channel, a pair of electrodes (C-NCP electrodes or commercial conductive Ag epoxy electrodes), electrical routing for signal transfer, and contact pads for connection to external equipment for testing. Screen printable Ag C-NCP (previously characterized for a different application in a previously published conference paper 18 ) is used to fabricate electrodes, electronic routing, and contact pads. Lastly, the sensor device is successfully tested with saline solutions at different salt concentrations to demonstrate the example device.…”

Beyond Conventional Patterns: New Electrochemical Lithography with High Precision for Patterned Film Materials and Wearable Sensors

“…photolithography technique) were generally adopted, − ,, which is involved in the complicated fabrication processes, expensive instruments, and the requirement of cleanroom environment, seriously limiting the mass production and practical applications of the resulting devices (∼1 h for every chip). To well solve these problems, the screen-printing, ink jet printing, and flexographic printing techniques were employed to coat and pattern the substrate simultaneously but still hampered by the problems of limited resolution (1200 dpi) and few printable inks available. ,,,,− Moreover, these techniques can hardly print the pure substance (additives in the ink), which may interfere with the performance of resulting chips in some cases. Recently, some interesting lithography approaches have been developed, which use hard or soft stamps for patterning various materials with high resolution at ambient conditions.…”