PEDOT:PSS-Based Temperature-Detection Thread for Wearable Devices

Abstract

In this research, we developed a wearable temperature-sensing element by dip dyeing threads in poly (3, 4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) (p-type conducting polymer) solution. The PEDOT:PSS was used to  dye the textile and it exhibited negative temperature coefficient characteristics in which the resistance decreases as the temperature increases. The fabricated temperature-detection thread achieved a sensitivity of 167.1 W/°C with 99.8% linearity in the temperature range of -50 to 80 °C. We anticipate that temperature sensors that apply our technology will be made as stitch- or textile-type for wearable devices, and they will be widely adopted for different applications such as in fitness, leisure, healthcare, medical treatment, infotainment, industry, and military applications, among others.

PEDOT:PSS modified Screen Printed Graphene-Carbon Ink based Flexible Humidity Sensor

“…In general, PEDOT:PSS exhibits a core shell like structure with PEDOT forming the core and PSS forming the shell. These molecules are sensitive to water molecules, as the humidity level increases, the hydrogen bond between the PSS and PEDOT weakens [27][28][29]. This results in enhanced distance between the core and the shell molecules, which effectively contributes to increased distance for the electrons to migrate and leads to enhanced resistance with the increase in humidity level [7].…”

Cloth Based Biocompatiable Temperature Sensor

“…The effect of variation in resistance of the sensor with temperature from room temperature (RT) to 60 ºC was systematically investigated. The change in the resistance of the sensor is attributed to the shift in the thermal energy leading to microstructural changes in PEDOT: PSS discussed in details [19,20]. The fabricated temperature sensor in the present work demonstrates a sensitivity of ~ 30°C/Ω (0.8 % / ºC) and ~ 25 % variation in the resistance at 60 ºC from RT.…”

“…The drop casting allows an easy way of depositing the sensitive material on the rough surface of cloth. Ni Fibres 0 to 100 0.48 [22] Gold 30 to 80 0.15 [23] Carbon Nanotubes 30 to 45 0.13 [24] PEDOT:PSS on Fibre -50 to 80 0.48 [25] PEDOT:PSS RT to 65 0.8 This Work Fig. 1: PEDOT: PSS dropped on cellulose fibre for temperature sensor and its vision towards integration of sensors on cloth bag for wireless application.…”

“…PEDOT: PSS is a p-type semiconductor and in which the resistance of the electrode decreases with increasing temperature due to the generation of holes in the valence band [20,21]. When temperature is increasing due to thermal energy the electrons are excited in the valence band and it creates holes in the valance band.…”

“…The conductivity of the electrode can be varied by adding dopant such as ethyl glycol, DMSO etc [21]. It was reported that, the length or area of the electrode also influencing on the sensing performance of the device [20]. A further study is required to investigate sensing performances in various conditions such as changing the conductivity of the electrode and area of the electrode.…”