Ultrasensitive and Highly Stable Resistive Pressure Sensors with. Biomaterial-Incorporated Interfacial Layers for Wearable

Transcription

1 Supporting Information Ultrasensitive and Highly Stable Resistive Pressure Sensors with Biomaterial-Incorporated Interfacial Layers for Wearable Health-Monitoring and Human-Machine Interfaces Hochan Chang,, Sungwoong Kim,, Sumin Jin, Seung-Woo Lee,, Gil-Tae Yang, Ki-Young Lee, and Hyunjung Yi,* Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea SEED Tech. Co., Bucheon, Gyeonggi-do, 14523, Republic of Korea present address: Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul, 01811, Republic of Korea *Corresponding Author: Hyunjung Yi S-1

2 Supplementary Figures Figure S1. Schematic illustration of the fabrication process of the elastomeric PDMS film studded with pyramidal microstructures and the formation of the interfacial layer of biomaterial-incorporated conductive nano-network. First, <100> Si water with 1000 nm thick thermally grown silicon oxide was patterned via photolithography to form square patterns. Size of the squares was 150 m with center-tocenter distance of 300 m. Then the oxide layer was wet-etched in buffered oxide etchant (BOE) solution to serve as the mask for wet etching of Si. The patterned wafer was wet-etched in potassium hydroxide solution (KOH, 60%) to produce pyramidal patterns via anisotropic etching of Si substrate. The surface of the pyramidal shaped mold was then vapor deposited using trichloro (1H,1H,2H,2H-perfluorooctyl) silane to facilitate the release of the mold. To fabricate the elastomer film studded with pyramidal microstructures, a 10:1 mixture of PDMS elastomer and cross-linker was de-gassed under vacuum and transferred onto the hard molds while spinning the wafer at 500 rpm to ensure homogeneous thickness. Then, the PDMS-spun Si mold was heated at 60~65 C for at least 12 h and then released. The assembled SWNT network was then transferred onto the PDMS film studded with the pyramidal microstructures. S-2

3 Figure S2. (a) Photograph of the freestanding M13 phage-swnt network floating in water. (b-d) Optical micrographs of the PDMS film studded with pyramidal microstructures before (b) and after (c,d) the transfer of the hybrid nano-network shown in topical and cross-sectional views. S-3

4 Figure S3. (a) Thickness, (b) roughness, and (c) sheet resistance values of M13 biomaterial-incorporated SWNT networks of various compositions of SWNT/M13 phage concentrations. Mean value ± SD and sample size (n) of three were used for all data presentation. S-4

5 Figure S4. (a) Comparison of the sheet resistance of the SWNT/M13 phage networks of the composition of 4:0.25 and 4:8 before and after the peeling test. Corresponding images for testing are also shown in the insets. Mean value ± SD and sample size (n) of three were used for data presentation. (b) Photographs showing the networks on the PDMS film and the sticky tape after the peeling test. S-5

6 Figure S5. Setup for the measurement of the piezoresistive response of the developed sensor. The force was applied using a custom-built load-cell system and the current level was measured using sourcemeter (Keithley) at 1 V. S-6

7 Figure S6. (a) The measured current values of the sensor (network composition of 4:0.25) under various loadings. (b) Comparison of piezoresistive response (current change versus pressure) of the sensors based on various network compositions (SWNT/M13 phage molar concentration ratio) of 4:0.25, 4:2, and 4:8. S-7

8 Figure S7. The I-V curves of the piezoresistive sensor (network composition of 4:8) measured at various loadings. S-8

9 Figure S8. (a) The piezoresistive sensor is attached on the insole in the shoes. (b) The real-time current response of the sensor during walking at different speed. (c) Detailed response of the current values shown in (b). The response time is estimated to be ~ 20 ms in this measurement configuration. S-9

10 Figure S9. Calibration curves for (a) the sensor #1 and (b) the sensor #2 used for the monitoring of pressure profiles during object manipulation. The dimensions of the active area of the sensor were 5 mm 5 mm and 1 mm thick foam film (black color) was attached to the top surface of each sensor for the measurement to ensure the homogeneous distribution of pressure. S-10

11 Supplementary Movie 1. Peeling test of the M13 phage-swnt hybrid nano-network on a PDMS film studded with pyramidal microstructures using a sticky tape. S-11