Development of a biomedical device with printed electronics technology

Abstract

The development of flexible electronic devices with printed electronics technology has recently attracted significant interest from scientists and researchers. This project focuses on the fabrication of flexible sensors, via printing technologies, with applications in medicine and biomedical engineering. Flexible biomedical sensors, make ideal use in wearable devices and other applications, where a traditional sensor would not be feasible. Specifically, in the context of this work, the primary focus lies in the design, fabrication and characterization of a flexible temperature sensor, implementedfor biomedical applications. This sensor is fabricated with screen-printing technology and its main element is Thermochromic (TC) inks, which alter their color in response to temperature. Several critical parameters, including, the sensor’s structure, the substrate material, the electrical, thermal-optical properties and overall performance, are evaluated to ensure the successful development of the sensor. The initial objective is to obtain experimental measurements to correlate the resistance with the temperature developed in the device. The sensitivity of the sensor mainly depends on the temperature coefficient of resistance (TCR), which was experimentally found to have a negative temperature coefficient (NTC), which implies a decrease in resistance in response to the increasing temperature. The analysis is followed by the correlation of the thermal field of the sensor through a thermal (IR) camera, with the optical field via photography. In combination with the fabricated sensor, an electronic setup based on the ESP32-WROOM-32D microcontroller, a voltage divider and a Wheatstone bridge, is also developed. In this setup, the microcontroller reads the resistance of the sensor and uses its temperature coefficient of resistance to calculate the detected temperature which then, logs it. The recorded data is then displayed in real-time to the user via a web server, IoT, or Bluetooth application. This device provides a solid foundation for the development of new types of flexible temperature sensors, holding significant promise both in the medical field and patient care.