# Simultaneous Sensing of Touch and Pressure by Using Highly Elastic e-Fabrics
## 1 Introduction  
In recent years, electronic skins (e-skins) for wearable systems have attracted a lot of attention from researchers [1, 2]. There have been many studies on the design and fabrication of e-skins with functionalities and mechanical properties comparable to natural skin in soft robotics [3, 4, 5, 6, 7], human physiological monitoring, health care [8, 9, 10, 11], and human-machine interfaces [12, 13, 14, 15, 16]. Most of the mechanisms of skin-like electronics are based on a relationship between pressure and electrical properties such as the resistance [17, 18] and capacitance [19, 20, 21, 22] of constituent conductive materials. To date, capacitive soft sensors have dominated research in this field due to good performance and better stability than resistive soft sensors. According to these principles, many e-skin studies have been reported; [PERSON] et al. [23] developed stretchable silicon nanoribbon electronics for a skin prosthesis. [PERSON] et al. [24] studied the development of a re-healable, recyclable, and malleable electronic skin based on a dynamic covalent thermoset nanocomposite. [PERSON] et al. [25] presented an e-skin tactile sensor matrix pixelated by position-registered conductive microparticles. [PERSON] et al. [26] researched a textile electronic skin enabled by a highly elastic spacer fabric and conductive fibers. However, limitations still exist in such studies such as insensitivity under touching without pressure, too high a sensitivity for large pressure applications, limited air permeability, or complex fabrication. In order to fulfill these aims, we propose a hybrid approach for e-fabricic skin by combining screen printing and heat transfer techniques. The design of the e-fabricic-like skin is based on the structure of multi-line capacitors with two main layers, which are composed of SWCNT/stretchable silver paste [27, 28, 29, 30, 31, 32] as electrode layers and special-structure fabrics as a dielectric layer. The resulting e-fabricic-skin has high flexibility, is breathable, lightweight, and has easy integration into clothing. The CNTs are toxic for theskin, but it will be covered by silver paste. To the knowledge of the authors, the toxicity of silver is very low, and there are no materials cheaper than and least harmful to the skin as silver [33] in order to make the electrode materials. More importantly, the SWCNT/stretchable silver paste material can increase the durability strongly needed in applications such as bending, stretching, or twisting. In addition, the special structure of the fabrics will not only protect the e-fabric skin under a large deformation (1000 kPa), but also ensure a fast response-recover time (<6 ms). In this work, we explored the feasibility of using spacer fabrics to achieve high repeatability and hysteresis-free pressure responses in the flexible capacitive pressure fabric systems. The manufacturing process, as shown in Figure 1, allows for rapid, reliable, and scalable production of large sensor sheets. As this process just focuses on printing the layers, it is simpler than other existing works [26; 34]. Otherwise, the screen-printing technologies are easy to approach and apply in industry. The fabrication method demonstrated the possibility of mass production for wide applications in soft robotics, health monitoring, human motion tracking, or prosthetics devices.