Advancing the pressure sensing performance of conductive CNT/PDMS composite film by constructing a hierarchical-structured surface

Enhanced Sensitivity of a Resistive Pressure Sensor Based on a PEDOT:PSS Thin Film on PDMS with a Random-Height Micropyramid Structure

The use of flexible pressure sensors has become increasingly widespread in a variety of applications, including wearable electronics and electronic skin. These sensors need to exhibit high sensitivity, wide detection limits, a fast response time, a linear response, and mechanical stability. In this study, we demonstrate a resistive pressure sensor based on randomly arranged micropyramid polydimethylsiloxane (PDMS) with a conductive poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) thin film with a sensitivity of 391 kPa-1, a response time of 52.91 ms, a recovery time of 4.38 ms, and a limit of detection (LOD) of 0.35 kPa. Electrodes are then connected to a pair of the proposed resistive pressure sensors that face each other to fabricate a pressure sensing device. We examine various characteristics of the fabricated device, including the changes observed when applying loads ranging from 0 to 2.58 kPa. The proposed sensor exhibits high sensitivity and a rapid response time.

Comprehensive Investigation of the Temperature-Dependent Electromechanical Behaviors of Carbon Nanotube/Polymer Composites

The performances of flexible piezoresistive sensors based on polymer nanocomposites are significantly affected by the environmental temperature; therefore, comprehensively investigating the temperature-dependent electromechanical response behaviors of conductive polymer nanocomposites is crucial for developing high-precision flexible piezoresistive sensors in a wide-temperature range. Herein, carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composites widely used for flexible piezoresistive sensors were prepared, and then the temperature-dependent electrical, mechanical, and electromechanical properties of the optimized CNT/PDMS composite in the temperature range from -150 to 150 °C were systematically investigated. At a low temperature of -150 °C, the CNT/PDMS composite becomes brittle with a compressive modulus of ∼1.2 MPa and loses its elasticity and reversible sensing capability. At a high temperature (above 90 °C), the CNT/PDMS composite softens, shows a fluid-like mechanical property, and loses its reversible sensing capability. In the temperature range from -60 to 90 °C, the CNT/PDMS composite exhibits good elasticity and reversible sensing behaviors and its modulus, resistivity, and sensing sensitivity decrease with an increasing temperature. At room temperature (30 °C), the CNT/PDMS composite exhibits better mechanical and piezoresistive stability than those at low and high temperatures. Given that environmental temperature changes have significant effects on the sensing performances of conductive polymer composites, the effect of ambient temperature changes must be considered when flexible piezoresistive sensors are designed and fabricated.

Recent Advances in Polymer Composites for Flexible Pressure Sensors

Pressure sensors show significant potential applications in health monitoring, bio-sensing, electronic skin, and tactile perception. Consequently, tremendous research interest has been devoted to the development of high-performance pressure sensors. In this paper, recent progress on the polymer composite-based flexible pressure sensor is reviewed. The parameters of pressure sensors, including sensitivity, linear response range, detection limit, response speed, and reliability, are first introduced. Secondly, representative types of pressure sensors and relevant working principles are introduced and discussed. After that, the applications in human physiology monitoring, health monitoring, artificial skin, and self-powered smart system are listed and discussed in detail. Finally, the remaining challenges and outlook of polymer composite-based flexible sensors are summarized at the end of this review paper. This work should have some impact on the development of high-performance flexible pressure sensors.

Recent Progress of Tactile and Force Sensors for Human-Machine Interaction

Human-Machine Interface (HMI) plays a key role in the interaction between people and machines, which allows people to easily and intuitively control the machine and immersively experience the virtual world of the meta-universe by virtual reality/augmented reality (VR/AR) technology. Currently, wearable skin-integrated tactile and force sensors are widely used in immersive human-machine interactions due to their ultra-thin, ultra-soft, conformal characteristics. In this paper, the recent progress of tactile and force sensors used in HMI are reviewed, including piezoresistive, capacitive, piezoelectric, triboelectric, and other sensors. Then, this paper discusses how to improve the performance of tactile and force sensors for HMI. Next, this paper summarizes the HMI for dexterous robotic manipulation and VR/AR applications. Finally, this paper summarizes and proposes the future development trend of HMI.