Soft ionic liquid multi-point touch sensor

The development of electronic skin (e-skin) and soft tactile sensing has recently attracted great interest. Here we report for the first time on a novel ionic liquid (IL) based soft pressure sensor with multi-point touch detection capability using 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]+[BF4]−) as a highly conductive sensing medium. The sensing mechanism is attributed to the repopulation of charge cations and anions in aqueous solution under pressure. The sensor can detect two dimensional touching positions with a sensitivity of −0.28% kPa−1. Our sensor showed good stability and temperature independence thanks to the incompressibility of IL in the range of touch pressure and the appropriate signal measurement configuration. We successfully demonstrated the sensor's capability to detect multi-point human touch with different pressure levels. Our simple design with smart structures and ease of fabrication processes enable the development of a soft and low-cost sensor with multiple-point sensing capabilities on a single chip

In-situ deposition of pressure and temperature sensitive e-skin for robotic applications

The development of a multimodal sensing platform with multiple layers for electronic skin (e-skin) sensing of temperature and pressure has attracted considerable interest to practical applications in soft robotics, human-machine interfaces, and wearable health monitoring. In this work, we demonstrated a new platform technology with multiple sandwiched layers of highly oriented carbon nanotube membrane and polyacrylonitrile for the integration of pressure and temperature sensory functionalities into a single platform that is thin, ultra-lightweight, flexible, and wearable. The key technology of in situ deposition of sensor platform on objects or in robot interface makes this a unique method for the development of e-skins for robotic applications, offering a new approach to wearable electronics and portable health care

Novel low-cost sensor for human bite force measurement

This paper presents the design and development of a low cost and reliable maximal voluntary bite force sensor which can be manufactured in-house by using an acrylic laser cutting machine. The sensor has been designed for ease of fabrication, assembly, calibration, and safe use. The sensor is capable of use within an hour of commencing production, allowing for rapid prototyping/modifications and practical implementation. The measured data shows a good linear relationship between the applied force and the electrical resistance of the sensor. The output signal has low drift, excellent repeatability, and a large measurable range of 0 to 700 N. A high signal-to-noise response to human bite forces was observed, indicating the high potential of the proposed sensor for human bite force measuremen

Pressure and temperature sensitive e-skin for in situ robotic applications

E-skin with physical sensing capability has attracted considerable interest towards practical applications in soft robotics, human-machine interfaces, and wearable health monitoring. However, the development of a multimodal sensing platform with multiple layers for e-skin sensing of temperature and pressure has faced challenges due to the typical use of bare or single sensing layers as well as the complication of integration of multifunctional sensing modules onto curved surfaces. Herein, we demonstrate a new platform technology with multiple sandwiched layers of highly oriented carbon nanotube (CNT) films and polyacrylonitrile (PAN) for integration of pressure and temperature sensory functionalities into a single platform that is thin, ultra-lightweight, flexible, and wearable. The key technology of in-situ deposition of sensor platform on objects or in robot interface makes this a unique method for the development of e-skins for robotic applications, offering a new approach to wearable electronics and portable health care

Low-Cost Graphite on Paper Pressure Sensor for a Robot Gripper with a Trivial Fabrication Process

A flexible pressure sensor with a rudimentary, ultra-low cost, and solvent-free fabrication process is presented in this paper. The sensor has a graphite-on-paper stacked paper structure, which deforms and restores its shape when pressure is applied and released, showing an exceptionally fast response and relaxation time of ≈0.4 ms with a sensitivity of −5%/Pa. Repeatability of the sensor over 1000 cycles indicates an excellent long-term stability. The sensor demonstrated fast and reliable human touch interface, and successfully integrated into a robot gripper to detect grasping forces, showing high promise for use in robotics, human interface, and touch devices

Fabrication of a sensitive pressure sensor using carbon nanotube micro-yarns

Developing flexible pressure sensors is of high interest in soft skin and tactile sensing applications. Here we demonstrate a simple approach to fabricating a sensitive resistive pressure sensor using carbon nanotube (CNT) micro-yarns as a pressure sensing element which is constructed on a stretchable acrylic elastomer. The sensor showed a high sensitivity of -0.86 Ω/kPa and a fast response time of 100 ms. Different to the longitudinal piezoresistive effect of micro-yarns, the high pressure sensitivity of the sensor was achieved owing to the compressibility of the micro-yarn in the direction perpendicular to the yarn axis. The sensor was also able to monitor finger pressure in real-time, demonstrating its potential for tactile sensing applications

Electrical resistance of carbon nanotube yarns under compressive transverse pressure

This letter reports on the impact of compressive pressure on the electrical properties of carbon nanotube (CNT) yarns fabricated by dry Web-spinning and heat-treatment processes. Under increasing applied compressive pressure in the radial directionof the yarn, the electrical resistance of CNT yarns gradually decreased by 2.8% at a threshold applied pressure of 60 kPa where the resistance change is saturated. The decrease of CNT resistance with increasing pressure is attributed to the increase in the volume fraction of CNT, resulting in the increase of the effective junctions between adjacent CNTs, and the reduction of the tunneling distance between single CNTs. CNT yarns embedded in elastomers show high potential as an advanced functional element for a wide range of mechanical sensing applications including flexible pressure and tactile sensing

Sensitive and fast response graphite pressure sensor fabricated by a solvent-free approach

This work demonstrates a biodegradable resistive pressure sensor fabricated by a solvent-free, low cost and highly efficient method. The sensor shows a high sensitivity of 4.77 %/kPa, a fast response of 0.3 ms and a relaxation time of 8 ms. The fast response time, flexibility, and capability to be safely attached to the human body and measure the motion of the Unger in real-time indicate its potential for human motion detection, touch displays, and tactile sensing applications