Adaptable pressure textile sensors based on a conductive polymer

Abstract

Recent studies in the field of safety in the workplace have focused on developing new sensors and procedures to detect and monitor body stress due to repeated or highly stressful movements that, in the long term, could lead to painful traumas or accidents. Today, the common method used to evaluate risk activities is based on evaluations that are subjective or supported by difficult and timeconsuming video analysis. However, recent developments in wearable sensors, in particular pressure sensors, allow for innovative alternatives. The main requirements of wearable pressure sensors are good wearability, allowing natural movements and a sensor response in a broad range of pressure to allow a large variety of possible activities to be monitored. In this paper, we report on a new promising class of textile pressure sensors based on the employment of a conductive polymer that can be easily deposited directly on the fabric, for example, to fabricate sensorized gloves to monitor hand stress during manual activity. The main advantages of the proposed technology comprise the possibility of selectively tuning the pressure response range, adapting it to different applications by changing the formulation of the conductive polymer while leaving the same device architecture and structures. We deposit and characterize the active sensing layer, analyze the pressure sensor response and propose an interpretation of the obtained results based on piezoresistive phenomena. We identify three different contributions to the sensor output, related to the macroscale, microscale and nanoscale, respectively. Finally, we describe the production of sensorized textile gloves with fully textile pressure sensors that are comfortable, reproducible, low cost and easily tunable in pressure range response.

Impact of Fabric Properties on Textile Pressure Sensors Performance

“…The textile sensors, based on conductive polymer PEDOT:PSS, consist of two conductive stainless steel threads that are in contact with each other through a fabric coated with such a polymer. Increasing the applied pressure, the thickness of the fabric decreases, the piezoresistivity of conductive polymer changes and the whole pressure sensor resistance decreases (conductance increase) [22,27].…”

“…The conductive ink was dried at room temperature. A commercial 2 ply stainless steel conductive thread (resistivity of ~10 ohms/m) has been sewn with lockstitch by the sewing machine Elna eXa 320 in the final pressure sensor configuration as described elsewhere [27].…”

“…The description of its working principle should take into account these challenging issues. We have recently reported an interpretation identifying three different contributions to textile pressure sensors performance [27]. At a macroscopic level the fabric properties, in terms of thickness, wettability and mechanical properties, are the most important factors that determine the pressure sensor performance.…”

Piezo-Sensitive Fabrics from Carbon Black Containing Conductive Cellulose Fibres for Flexible Pressure Sensors

“…The combination of conductive films and deformable insulating layers permits construction of capacitors with pressure-sensitive capacity [ 11 , 12 , 13 ]. Similarly, two conductive lines, woven into a fabric or wrapped in ply structure and separated by an elastic material, have been proposed as thread-like capacitive pressure sensors [ 14 , 15 , 16 ].…”

Design and Development of a Low-Cost Wearable Glove to Track Forces Exerted by Workers in Car Assembly Lines

“…Devices have also been designed to protect workers’ health, including the Smart Cap, which collects fatigue related data to increase worker safety in fields like mining or the transport industry, and the Vandrico [18] hat, which provides cooling for the comfort of athletes, firefighters, surgeons and pilots. Companies that provide wearable technology include TekSan [19], which has developed a system for tracking grip pressure and has conducted research focused on textile sensors based on conductive polymers [20].…”