Highly piezoresistive compliant nanofibrous sensors for tactile and epidermal electronic applications

Abstract

Abstract

Novel Flexible Wearable Sensor Materials and Signal Processing for Vital Sign and Human Activity Monitoring

“…Another modality for HR monitoring which is coming to focus in the recent years is the application of flexible strain or pressure sensors. Soltanian et al [ 13 ] reported a soft and conformable strain sensor made from a mesh of conductive nanofiber (NF) encapsulated in an elastomer ( Figure 4 a). Flexible piezoresistive sensors (FPS), which are manufactured using electrospinning—a versatile method for economic nanomaterial fabrication—demonstrates a fast, low-voltage, accurate, repeatable strain sensing behavior with a strain gauge factor as high as 60 ( Figure 4 b).…”

“…Flexible piezoresistive sensors (FPS), which are manufactured using electrospinning—a versatile method for economic nanomaterial fabrication—demonstrates a fast, low-voltage, accurate, repeatable strain sensing behavior with a strain gauge factor as high as 60 ( Figure 4 b). Low power sensor operation down to μW will be feasible using this sensor [ 13 ]. The strain-sensitivity is attributed to the reversible disjointing/jointing of inter-NF junctions held together by a spring action of the encapsulating elastomer.…”

“…Other groups have shown use of strain sensors for detection of muscle contraction and expansion. For example, Soltanian and Servati et al [ 13 ] attached a nanofiber based strain sensor to the flexor bundle of the forearm to monitor flexion and extension movements of the wrist and fingers ( Figure 8 a). Having the same sensor on the flexor bundle they reported accurate monitoring of simulated intermittent Parkinson’s tremors ( Figure 8 b).…”

“… Application of strain and pressure sensors for heart rate monitoring: ( a ) flexible piezoresistive strain sensor fabricated by electrospinning and encapsulated in PDMS; ( b ) exceptional gauge factor of 60; and ( c ) detection of heart rate and pulse waveform by attaching the sensor on radial artery (Reprinted with permission [ 13 ]. Copyright 2014, Cambridge University Press); ( d ) flexible pressure sensing film; and ( e ) array of micro-pyramid shape structures fabricated on poly(glycerol sebacate) (PGS); ( f ) Blood pulse wave of the radial artery detected by the pressure sensor (Reprinted with permission [ 14 ].…”

“… Sensors for non-invasive muscle and joint monitoring. ( a ) Application of nanofiber sensor attached to epidermis of forearm flexor bundle monitoring hand gestures: (I) neutral hand position; (II) repeated wrist flexion; (III) subsequent flexion of the second, third and fourth digits; and (IV) repeated wrist extension; ( b ) Accurate monitoring of simulated intermittent Parkinson’s tremors by nanofiber sensor attached to subject’s forearm (Reprinted with permission [ 13 ]. Copyright 2014, Cambridge University Press); ( c ) Photographs from a typical single-wall carbon nanotube (SWCNT) wire embedded in PDMS (top) and the cracks happening in the wire caused by stretch (bottom); ( d ) CNT wire sensor mounted on fingers detecting finger flexion and extensions (Reprinted with permission [ 56 ].…”