Towards wearable pressure sensors using multiwall carbon nanotube/polydimethylsiloxane nanocomposite foams

Highlights: • MWCNT/PDMS nanocomposite foams exhibit negative pressure coefficient of expansion. • Electrical resistance decreases with compression as conducting paths form between MWCNT protruding from pore walls, as pores collapse. • Maximal force computed using MWCNT/PDMS nanocomposite sensels integrated in a sports glove is in accordance those obtained using the gold standard Jamar dynamometer. The use of multiwall carbon nanotube/polydimethylsiloxane (MWCNT/PDMS) nanocomposite in pressure sensors for healthcare and sports applications promises great benefits due to ease of its fabrication and mechanical robustness. In this study we investigate the effect of porosity in MWCNT/PDMS nanocomposites on its pressure sensing property. In contrast to its dense counterpart, MWCNT/PDMS nanocomposite foams exhibit negative pressure coefficient of resistance (NPCR) in which resistance decreases with applied pressure. This behavior is explained in terms of conducting paths formed between MWCNT protruding from walls of pores which are collapsing during compression. Normalized resistance change, computed from resistance data, increases at a slower rate for higher MWCNT loading in the range of variables investigated. A sports glove with integrated MWCNT/PDMS nanocomposites foam sensing elements (sensels) was fabricated. Maximal grip strengths determined using the sports glove are in agreement to those obtained using the Jamar dynamometer and Martin vigorimeter reported in the literature.