Fig. 5: Piezo electronics sensor made of ionic-gel transistor.

a Schematic diagram of the device structure of an OECT. b quivalent circuits in an OECT and schematic diagram of the proposed microstructured hydrogel-gated OECT iontronic pressure sensor. The deformation of the hydrogel determines the number of ions delivered into the channel. c) V_g and V_sol change after application of external pressure on the gate electrode. d SEM image of gelatin methacryloyl (GelMA) hydrogel with pyramidical microstructures on the surface; Lower picture is a real optical image of the OECT iontronic pressure sensor. Reproduced with permission⁸⁴. Copyright 2021, IEEE. e Schematic diagram of a GFET pressure sensor fabricated with interdigitated source electrodes. f Spatial pressure graph of GFET pressure sensor matrix. g Pressure sensing characteristics of GFET pressure sensor mounted on PDMS rubber substrate. The illustration shows the GFET matrix making angular contact with human hands or table tennis. Reproduced with permission⁸³. Copyright 2014, Wiley-VCH. h Mechanism of GT strain sensing based on piezoelectric potential gating. i Sensitivity and stability characteristics of piezoelectric gated GT strain sensor. Reproduced with permission⁵⁸. Copyright 2015, Wiley-VCH. g Process for manufacturing multi-level non-volatile memory array for piezoelectric potential programming. k Real-time programming and erasing steps applied to piezoelectric potential programming memory. Reproduced with permission⁹³. Copyright 2016, American Chemical Society.