Thin single-layer textile-based matrix-type pressure sensor for protective clothing

The research focuses on the development of an ultra-thin, single-layer, matrix-type textile pressure sensor for the field of smart textiles, which can record the location of pressure application and determine the applied force. The sensor possesses the tactile characteristics of a textile, and its design incorporates only textile-based materials, ensuring greater flexibility and improved integration with textile materials. The research describes the study of piezo-resistive electro-conductive textiles and identifies the most suitable materials for creating the sensor. Testing was performed using a Zwick/Roell Z2.5 compression/strain test column and an Agilent A34970A ohmmeter. Testing focused on the sensor’s electrical resistance changes under cyclic loading, sensitivity, measurement hysteresis, and repeatability. From the experiments can summarise that for the Sefar Carbotex 03-120CF sensor load cycling repeatability varies significantly depending on the pressure point and it is difficult to summarize an approximate range of changes in the load and resistance values and hysteresis values changes in most cases from 0,44 to 0,94. The best results showed the EeonTex LTT-SLPA 60 kOhm sensor with better cycling repeatability in the low, middle and high range, and the values at different pressure points are comparable and hysteresis values changes in most cases from 0,83 to 0,94. It was found that the sensitivity values of the Sefar Carbotex 03-120CF sensor are in range of 0,004–0,05 KPa but values of the EeonTex LTT-SLPA 60 kOhm sensor–in range of 0,002–0,005 kPa. For the Carbotex fabric sensor with the increase in pressure resistance decreases, but for the Eontex fabric sensor, it increases. This can be explained by the elasticity of the Eontex fabric, as it is made of knitted fabric. A design for sensor electrodes is created using embroidery software, and electrodes made of electroconductive thread are produced using automated embroidery technology. To visually display the sensor’s operation on screen, a serial interface is used with tailor-made software. The development of this type of textile sensor would contribute to various wearable applications for protective clothing, such as in fencing equipment for sports or in the field of bullet impact detection in soft armor and protective clothing for operators working in environments with a risk of injury from impact with moving parts or falling objects, such as heavy agricultural machinery operators and first responders as well in medical application in mattress toppers to monitor body impressions.