Simultaneous Sensing of Touch and Pressure by Using Highly Elastic e-Fabrics

Abstract

In recent years, electronic skins have been widely studied for human monitoring systems. This research field needs multi-sensing points for large deformation, strong recovery, and mass production methods. Toward these aims, the fabrication of e-fabric skins made from a capacitive touch sensing layer and a capacitive pressure sensing layer is presented in the paper. Due to the high elasticity of the dielectric layer of the spacer fabric, this structure exhibits a very fast recovery time (6 ms), low hysteresis (<5%), and high cycling stability (>20,000 times). Besides, the stacking structure of the electrode layers ( single-wall carbon nanotube/silver paste) is due to good durability even under large deformations (grasping, bending, stretching), and the skin is breathable for applications. As expected, the e-fabric skin is proven to be robust for detecting a spatial pressure distribution in real time. The extremely simple fabrication process is also an extra plus point in view of point mass production.

Fabrication Approaches of Soft Electronics

“…Vu et al 106 (Figure 2b) reported on the fabrication of efabric skin with fast response-recovery time, by combining two sensor layers. The sensors were made by screen printing of commercial ink containing single-walled CNT (SWCNT) and silver particles stretchable ink.…”

“…(B) Structure of the capacitive sensor layer, real picture of the capacitive sensor layer, and working principle of the capacitive sensor layer. Reprinted with permission from ref . Copyright 2020 MDPI.…”

Direct-Ink Writing Processing of High-k Poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) and Its Integration into an All-Printed Capacitive Touch-Sensing Device

“…Furthermore, as the demand for facile integration, increasing complexity, and customized electronic devices rises, the need for efficient and precise manufacturing techniques grows. , Thus, additive manufacturing technologies, including inkjet printing, − gravure, , screen printing, − and direct-ink writing (DIW), , have been used to deposit various conductive and nonconductive functional patterns on rigid and flexible substrates. Screen printing is an additive manufacturing technique with superior material utilization, low process temperatures, the ability to handle large-scale production at low cost, and a printing process fast enough for mass production .…”

The enhancement of sensitivity and response times of PDMS-based capacitive force sensor by means of active layer modification

“…providing linear correlation between an applying force and a change in capacitance and exhibiting less hysteresis behavior during an operation. 8) One of the materials famously used in such sensors is polydimethylsiloxane (PDMS) owing to an excellence in mechanical properties, less toxicity, and biocompatibility as well as being simple to fabricate. [9][10][11] However, capacitive force sensor based on PDMS encounters limitations in low sensitivity and slow response/recovery time.…”