3D Printing of Liquid Metal Based Tactile Sensor for Simultaneously Sensing of Temperature and Forces

Abstract

Tactile sensors have been used for haptic perception in intelligent robotics, smart prosthetics, and human-machine interface. The development of multifunctional tactile sensor remains a challenge and limit its application in flexible electronics and devices. We propose a liquid metal based tactile sensor for both temperature and force sensing which is made by 3D printing. The structural design and working principle of liquid metal based tactile sensor are firstly described. A digital light processing-based printing process is developed to print two kinds of photosensitive resins with different hardness, and used to fabricate the tactile sensor. A Wheatstone bridge circuit is designed for decoupling the temperature and forces from the measured output voltages. Characterization tests show that the tactile sensor has relatively high force sensing sensitivity of 0.29 N -1 , and temperature sensing sensitivities are 0.55% °C −1 at 20 ~ 50 °C and 0.21% °C −1 at 50 ~ 80 °C, respectively. Then, the fabricated tactile sensor is mounted onto hand finger to measure the contact force and temperature during grasping. Results show that the 3D printed tactile sensor has excellent flexibility and durability and can accurately measure the temperature and contact forces, which demonstrate its potential in robotic manipulation applications.

Emerging Role of Liquid Metals in Sensing

“…The decoupling was accomplished by a structural design based on two central resistors with protrusion which were mostly sensitive to the external force, while all four resistors utilized in the fingerprint design were sensitive to temperature. A similar Wheatstone bridge design with Galinstan-filled channels was fabricated through digital light processing (DLP)-based 3D printing to improve the manufacturing efficiency …”

“…A similar Wheatstone bridge design with Galinstan-filled channels was fabricated through digital light processing (DLP)-based 3D printing to improve the manufacturing efficiency. 109 ■ LM-BASED CHEMICAL SENSORS In addition to the remarkable physical properties of LMs, elaborated in the earlier sections, Ga-based LMs possess intriguing chemical features well-suited for developing different chemical sensors. These features may originate from their interface, core, or both.…”

Review on Microscale Sensors with 3D Engineered Structures: Fabrication and Applications

“…A tactile sensor is constructed by digital light processing 3D printing, [ 60 ] which is similar to SLA. The diluted resin is selectively patterned into soft microfluidic channels for easy deformation, while the pure resin is patterned to the hard cover layer for protection (Figure 5c(i)).…”

“…Nitrate sensors [58] Channel Glucose sensors [59] Channel Tactile sensors [60] Molding Traditional molding Simple process; low cost Limited structures; difficult to remove the templates Pyramid Tactile sensors [21] Bump Tactile sensors [61] Interlocking Tactile sensors [62] Templating Simple process; low cost Limited structures; difficult to remove the templates Porous structure Gas sensors [63] Porous structure Pressure sensors [64] Conformal additive stamp printing Transferability Complicated operation Hemisphere Smart contact lenses [65] Hemisphere Artificial eyes [66] Stress-induced assembly Pre-stored stress Simple process Limited structures; irreversibility…”

“…Copyright 2015, Wiley-VCH. c) Tactile sensors: i) 3D printing process of the microfluidic channels of the tactile sensor, ii) Galinstan injection and sealing, electrical response of the tactile sensor to iii) force and iv) temperature; adapted under the terms of the CC-BY 4.0 Creative Commons Attribution License [60]. Copyright 2021, The Authors, published by Taylor & Francis.…”