fig8

Figure 8. Pressure sensors. (A) Schematic illustration of resistive sensing mechanism (left) and relative resistance change of the GNP/PU film with finger pressures (right). Reproduced with permission from ref^[70]. Copyright 2017, American Chemical Society; (B) Schematic illustration of the flexible pressure sensor based on PVDF/PANI nanofibers (left) and relative current response for different gaits (right). Reproduced with permission from ref^[180]. Copyright 2021, American Chemical Society; (C) Schematic illustration of the PPy/AgNP hybrid film through interfacial photopolymerization (left) and detection of respiration rate with different breathing patterns using the film as a pressure sensor (right). Reproduced with permission from ref^[183]. Copyright 2021, Elsevier B.V; (D) Materials and device structure of the FPS with and without applied pressure (left). Blood pressure obtained from the FPS and conventional photoplethysmogram sensor (right). Reproduced with permission from ref^[187]. Copyright 2015, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim; (E) Schematic illustration of stacked LM-PVA films under pressing (left) and relative capacitance change with increasing pressure (right). Reproduced with permission from ref^[188]. Copyright 2020, Elsevier B.V; (F) Preparation of the F-TENGs and structural representation of the F-TENG-based tactile sensor arrays (middle). Image of the sensor array with an H-shaped object and corresponding pressure distributions (right). Reproduced with permission from ref^[189]. Copyright 2020, Wiley-VCH GmbH. AgNP: Silver nanoparticle; AgNWs: silver nanowires; BP: blood pressure; CNT: carbon nanotube; FPS: flexible piezoresistive sensor; F-TENG: fiber-shaped triboelectric nanogenerator; GF: gauge factor; GNP: graphite nanoplate; PANI: polyaniline; PDMS: polydimethylsiloxane; PPy: polypyrrole; PU: polyurethane; PVA: poly(vinyl alcohol); PVDF: polyvinylidene fluoride; UV: ultraviolet.