Multifunctional Inkjet-Printed Silver Structures for Wearable Biosensors

Silver patterns were printed on a flexible polyethylene terephthalate (PET) substrate with an inkjet printing method, to explore the possibility of incorporating it into wearable devices. The proposed resistive structure allows for additional sensing for the acquisition of multiple health indicators at the same time, such as sweating and temperature, by incorporating additional interdigitated electrodes. It was found that the resistive part of the structure exhibits linear dependence of the thermal coefficient of resistance on the temperature in the range of the human temperature and even out of it. The sensitivity of the structure was ~1.4x10
^-3
℃
^-1
. While the humidity sensor has a standard interdigitated pattern, the temperature sensor has a unique pattern of a rosette. The rosette shape can provide more precise temperature measurements by capturing thermal changes in a variety of directions. The multiple arms of the rosette design can enable better spatial resolution, allowing for a more detailed understanding of temperature distribution across a surface. The rosette shape can also offer versatility in applications by accommodating different mounting orientations or surface shapes. The internally nested humidity sensor exhibited a maximal sensitivity of ~ 3.5 pF/%RH.