Gradual Electrical-Double-Layer Modulation in Ion-Polymer Networks for Flexible Pressure Sensors with Wide Dynamic Range

To realize flexible pressure sensors with high sensitivity, surface-textured soft films have often been adopted and the contact area can vary significantly depending on the applied pressure. However, the contact area modulation realized in such a way is subject to a limited dynamic range, and its infinitesimal zero-pressure contact area raises concerns regarding durability. Herein, a flexible pressure sensor made of a texturing-free piezocapacitive layer based on ion-polymer networks is proposed. In this scheme, ion infiltration leads to electrical-double-layer modulation that gradually varies over a wide range of applied pressures. The proposed flexible pressure sensors with the optimal ion concentration are shown to exhibit both excellent mechanical durability and linear responses with high sensitivity over a wide pressure range up to 1 MPa. With the simple fabrication route, high performance, and reliability, the proposed approach may open up a new avenue for skin-like pressure sensors ideal for many emerging applications. A piezocapacitive film with huge capacitance variation of 3000 times is achieved using a mechanism of electrical-double-layer modulation, that is enabled by a change of relative concentration of ionic liquid in a polymer network film according to thickness reduction. This planar, texture-free, and very thin film shows superlinear response to a wide range of pressure up to 1 MPa. image

Automated summary

A flexible pressure sensor based on a texturing-free piezocapacitive layer is proposed, which utilizes ion infiltration for electrical-double-layer modulation and exhibits excellent mechanical durability and linear response over a wide pressure range.