Recent Progress in Development of Wearable Pressure Sensors Derived from Biological Materials

Abstract

This review summarizes recent progress in the use of biological materials (biomaterials) in wearable pressure sensors. Biomaterials are abundant, sustainable, biocompatible, and biodegradable. Especially, many have sophisticated hierarchical structure and biological characteristics, which are attractive candidates for facile and ecologically‐benign fabrication of wearable pressure sensors that are biocompatible, biodegradable, and highly sensitivity. The biomaterials and structures that use them in wearable pressure sensors that exploit sensing mechanisms such as piezoelectric, triboelectric, piezoresistive and capacitive effects are present. Finally, remaining impediments are discussed to use of biomaterials in wearable pressure sensors.

Morphological Engineering of Sensing Materials for Flexible Pressure Sensors and Artificial Intelligence Applications

“…Generally, when external pressure is applied to the device, the deformation of the oriented non-centrosymmetric crystal structures leads to the spatial separation of the positive and negative charges, resulting in charges on the cathode and anode. Commonly used piezoelectric sensing materials include piezoelectric crystals (lead zirconium titanate (PZT) [ 169 , 170 ], gallium nitride (GaN) [ 171 ], BaTiO 3 (BTO) [ 172 ], zinc oxide (ZnO) [ 25 ], aluminum nitride (AlN) [ 173 ]), piezoelectric polymers (PVDF [ 174 – 176 ], cellular polypropylene [ 177 ], fluorinated ethylene propylene (FEP) [ 2 , 32 ], cyclic olefin copolymer (COC) [ 178 ]), bioderived piezoelectric materials [ 125 ] (onion skin [ 179 ], spider silk [ 180 ], eggshell [ 181 ]), piezoelectric peptide and metabolite materials [ 182 ] (diphenylalanine (FF) [ 183 ], β glycine [ 184 ], cyclo-glycine-tryptophan (cyclo-GW) [ 185 ]). Piezoelectric sensors are widely used to detect pressure and high-frequency vibration dynamically due to their high sensitivity and transient sensing ability.…”

“…Several reviews have summarized the progress in flexible pressure sensors, focusing on flexible electronics [ 68 , 122 ] and emerging materials (e.g., graphene-based [ 123 , 124 ], biological materials [ 125 ]). Additionally, the structure design of pressure sensors has been addressed in some of them, such as three-dimensional (3D) monolithic conductive sponge [ 126 ], microstructures geometrical design [ 38 , 125 , 127 , 128 ], microengineering of sensing layer with geometric features ≈ 1–1000 µm in size [ 129 ].…”

“…Several reviews have summarized the progress in flexible pressure sensors, focusing on flexible electronics [ 68 , 122 ] and emerging materials (e.g., graphene-based [ 123 , 124 ], biological materials [ 125 ]). Additionally, the structure design of pressure sensors has been addressed in some of them, such as three-dimensional (3D) monolithic conductive sponge [ 126 ], microstructures geometrical design [ 38 , 125 , 127 , 128 ], microengineering of sensing layer with geometric features ≈ 1–1000 µm in size [ 129 ]. However, there is still an urgent need to comprehensively summarize the progress of morphological engineering of sensing material in pressure sensors as they may provide additional insights on compatibility and sensing performance such as sensitivity, limit of detection, dynamic range, stability, and response and relaxation times.…”

A Biodegradable and Recyclable Piezoelectric Sensor Based on a Molecular Ferroelectric Embedded in a Bacterial Cellulose Hydrogel

“…, cellulose), animal-derived polymers ( e.g. , collagen, and silk fibroin), and artificially synthesized polymers [degradable polymers, e.g ., poly­(vinyl alcohol) (PVA) and poly­(glycerol sebacate) (PGS)] with conductive nanofillers such as carbon nanotubes and graphene have been developed. − Moreover, recent works have demonstrated that biomaterials such as silk, paper, and linen with three-dimensional (3-D) interconnected structures can be used for piezoresistive sensors, which are biodegradable as well . Similar strategies have been applied to piezocapacitive sensors.…”

Flexible pressure sensors via engineering microstructures for wearable human-machine interaction and health monitoring applications

“…The working mechanism of capacitive pressure sensors is the transduction of external pressure stimuli into a change in the capacitance of a parallel plate capacitor (Zhang et al, 2021b). For piezoelectric pressure sensors, the working principle is the separation of electric dipole moments resulting from the deformation of piezoelectric crystals under pressure, generating electrical signals (Guo et al, 2018;Pan and Lee, 2021). In addition, triboelectricity is another transduction method for pressure sensing, which refers to the generation of different current or voltage signals under different pressures by triboelectrification and electrostatic induction (Luo et al, 2021).…”