Figure 3

Solid-state physical sensing platforms. (a) Stretchable strain sensors based on the nanohybrid assembly of SWCNTs and PEDOT:PSS. (i) Schematic cross-section illustration of the device comprising stacked layers of PU-PEDOT:PSS, SWCNT, and PEDOT:PSS on a PDMS elastomer. (ii) Scanning electron microscope (SEM) image showing the top view of the three-layer nanohybrid strain sensor. Adapted with permission from Ref. 34. Copyright 2015 American Chemical Society. (b) All-carbon multimodal piezocapacitive stretchable skin sensor. (i) Schematic illustration showing the active layers of the hierarchically engineered CNT microyarn-based sensor. (ii) SEM image of the surface of the CNT microyarns (left). Scale bar, 1 μm. Inset shows the hydrophobic nature of the surface. Cross-sectional SEM image of the CNT microyarn-incorporated layered structure (right). Scale bar, 50 μm. Adapted with permission from Ref. 35. Copyright 2015 Wiley-VCH Verlag GmbH & Co. (c) AuNW-coated tissue paper-based flexible pressure sensor. (i) Schematic illustration showing the fabrication process of the pressure sensor. (ii) Optical image showing the flexibility of the fabricated device. (iii) SEM image showing the surface morphology of the AuNW-coated tissue paper. Scale bar 100 μm. Adapted with permission from Ref. 3. Copyright 2014 Macmillan Publishers Limited. (d) Stretchable and breathable skin-inspired temperature sensor. (i) Device architecture of the temperature sensor. (ii) SEM image showing the cross-section of the semipermeable PU film (left), the surface of the semipermeable PU film (center), and the microstructure of the PU layer of the semipermeable membrane. Adapted with permission from Ref. 101. Copyright 2015 Macmillan Publishers Limited. AuNW, Au nanowire; CNT, carbon nanotubes; PU, polyurethane; SEM, scanning electron microscope; SWCNTs, single-walled CNTs.