Soft Conductive Hydrogel-Based Electronic Skin for Robot Finger Grasping Manipulation

Abstract

Electronic skin with human-like sensory capabilities has been widely applied to artificial intelligence, biomedical engineering, and the prosthetic hand for expanding the sensing ability of robots. Robotic electronic skin (RES) based on conductive hydrogel is developed to collect strain and pressure data for improving the grasping capability of the robot finger. RES is fabricated and assembled by the soft functional materials through a sol–gel process for guaranteeing the overall softness. The strain sensor based on piezoresistive hydrogel (gauge factor ~9.98) is integrated onto the back surface of the robot finger to collect the bending angle of the robot finger. The capacitive pressure sensor based on a hydrogel electrode (sensitivity: 0.105 kPa−1 below 3.61 kPa, and 0.0327 kPa−1 in the range from 4.12 to 15 kPa.) is adhered onto the fingertip to collect the pressure data when touching the objects. A robot-finger-compatible RES with strain and pressure sensing function is designed for finger gesture detection and grasping manipulation. The negative force feedback control framework is built to improve grasping manipulation of the robot finger with RES, which would provide a self-adaptive control method to determine whether the objects are grasped successfully or not. Robot fingers integrated with soft sensors would promote the development of sensing and grasping abilities of the robot finger and interaction with human beings.

Skin-like hydrogels: design strategy and mechanism, properties, and sensing applications

“…1C). [86][87][88][89] Capacitive skin-like hydrogel will change the capacitor signal by changing the internal structure of the capacitor (such as the contact area and dielectric thickness), so as to feel the stimulation. 90 The formula is as follows:…”

“…81,82,92 Skin-like hydrogels based on stress-strain detection often mimic the ability of human skin to perceive pain and movement. 87,93 However, skin-like hydrogels can also detect temperature and humidity signals like human skin, and can recognize some chemicals, which skin cannot detect. In order to simulate the temperature perception of skin, skin-like hydrogels are usually achieved by introducing thermistors.…”

“…1C). 86–89 Capacitive skin-like hydrogel will change the capacitor signal by changing the internal structure of the capacitor (such as the contact area and dielectric thickness), so as to feel the stimulation. 90 The formula is as follows: C = εS / d where ε , S and d are the dielectric constant, contact area and thickness of the dielectric conductive layer, respectively.…”

A Composite of Hydrogel Alginate/PVA/r-GO for Scaffold Applications with Enhanced Degradation and Biocompatibility Properties

“…This area needs three important aspects, namely cells, bioactive molecules, and scaffolds [ 1 , 2 ]. On the other hand, a biomaterial known as hydrogel is employed in biomedical applications such as tissue engineering, drug delivery, wound dressing, and soft tissue electronics owing to its unique properties, such as biocompatibility and the capacity to mimic many characteristics of the natural [ 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Hydrogels are increasingly being used since they can mimic the specific environment of the extracellular matrix and in bioprocess engineering for immobilizing cells or enzymes as catalysts, drug carriers, cartilage and skin substitutes, wound dressings, a scaffold for cell culture, and as an antifouling agent [ 9 , 10 ].…”

Electroactive and Stretchable Hydrogels of 3,4-Ethylenedioxythiophene/thiophene Copolymers

“…Conductive hydrogels are important materials for the fabrication of flexible and wearable electric sensors because of their outstanding designability, good biocompatibility, high stretchability, excellent electrical conductivity, strong adhesion, and so on. − These well-designed conductive hydrogels have been extensively used in the field of electronic skins, − wearable devices, − flexible sensors, − human motion monitoring, , and brain–computer interface …”