Pressure Insensitive Strain Sensor with Facile Solution-Based Process for Tactile Sensing Applications

Abstract

Tactile sensors that can mechanically decouple, and therefore differentiate, various tactile inputs are highly important to properly mimic the sensing capabilities of human skin. Herein, we present an all-solution processable pressure insensitive strain sensor that utilizes the difference in structural change upon the application of pressure and tensile strain. Under the application of strain, microcracks occur within the multiwalled carbon nanotube (MWCNT) network, inducing a large change in resistance with gauge factor of ∼56 at 70% strain. On the other hand, under the application of pressure to as high as 140 kPa, negligible change in resistance is observed, which can be attributed to the pressure working primarily to close the pores, and hence minimally changing the MWCNT network conformation. Our sensor can easily be coated onto irregularly shaped three-dimensional objects (e.g., robotic hand) via spray coating, or be attached to human joints, to detect bending motion. Furthermore, our sensor can differentiate between shear stress and normal pressure, and the local strain can be spatially mapped without the use of patterned electrode array using electrical impedance tomography. These demonstrations make our sensor highly useful and important for the future development of high performance tactile sensors.

Ti3C2Tx MXene-graphene composite films for wearable strain sensors featured with high sensitivity and large range of linear response

“…Currently used sensing materials mainly include carbon materials (e.g. carbon black, carbon nanotubes and graphene) [14][15][16][17][18][19][20][21], metal materials (e.g. Ag nanowires and Au nanoplates) and so on [22][23][24][25][26][27][28][29].…”

“…For example, Park et al fabricated a strain sensor based on a Au nanoparticle thin film, and the sensor exhibited a maximum GF of 2.05 at the maximum strain of 20% [27]. One-dimensional materials are inclined to exhibit substantial stretchabilities and endow the strain sensor with a wide strain sensing range [21,22,28,29]. Cheng et al presented an Au nanowires based strain sensor, which can be stretched as wide as 350% [28], and the enokitake-like Au nanowire based strain sensor made by the same team demonstrated a ultrahigh stretchability of 800% strain.…”

Highly Uniform and Low Hysteresis Piezoresistive Pressure Sensors Based on Chemical Grafting of Polypyrrole on Elastomer Template with Uniform Pore Size

“…Porous structures, in particular, was utilized in various pressure sensors due to their facile fabrication process and scalability. Porous structure can be fabricated either by filling a 3D template such as sugar, nickel foam with an elastomer and subsequently etching away the template, or by mixing aqueous and oil solutions to form an emulsion and removing the solvents 4b,14…”

Highly Sensitive Temperature Sensor: Ligand‐Treated Ag Nanocrystal Thin Films on PDMS with Thermal Expansion Strategy

“…In these fields, many applications require precise temperature measurement. With the current interest in flexible electronics, the importance of flexible material based sensors, which can be applied as wearable, attachable devices, has also increased. In order to realize highly sensitive and reliable temperature sensors with diverse forms, various types of sensors have been developed in conjunction with investigations related to emerging materials and fabrication processes.…”