A Textile Proximity/Pressure Dual-Mode Sensor Based on Magneto-Straining and Piezoresistive Effects

The demand for flexible tactile sensors with both contact and contactless sensing capabilities is growing rapidly in the fields of smart robotics and prosthesis. However, it is still a challenge to integrate high performance proximity and pressure sensing functions in one sensor through simple fabrication process. Here, we propose a textile-based dual-mode sensor that can work on both magneto-straining mode (proximity) and piezoresistive mode (pressure). The sensor is simply fabricated by coating two functional materials in a concentric pattern, i.e., a magnetic layer followed by a conductive layer made of 2D MXene composite, on spandex substrate. As the dual-mode sensor approaches to a magnetic object, the attractive magnetic force will stretch the magnetic layer, along with the conductive layer. The strained conductive layer causes an increase of the resistance. Upon contact, the magnetic force reaches its maximum, while the pressure force works against the magnetic force and starts to reduce the strain of the conductive layer, leading to a decrease of the resistance. The turning point of the resistance can be used to identify the contact moment, and as an indicator of the switching of the two working modes of the sensor. Benefitting from the superior conductivity of the MXene material in the conductive layer, high sensitivity for both proximity sensing (13.76 mm
⁻¹
) and pressure sensing (0.7 kPa
⁻¹
) was achieved. The proposed dual-mode sensing methodology has great potential in human-machine interaction (HMI) applications.