Piel electrónica termosensible para prótesis de falanges

Abstract

In this project, the characterization of the velostat material as a temperature sensor was carried out, first determining the operating range (20 °C to 50 °C) and subsequently evidencing the presence of a significant error percentage in the hysteresis (9.61 %) and repeatability (6.27 %) parameters, which limits its application. So the fabrication of the thermosensitive electronic skin with a commercial sensor (NTC thermistor) was established after performing its respective characterization and comparing it with that of the velostat sensor. The fabrication of the thermosensitive electronic skin was carried out with low-cost flexible materials such as insulating tape and copper tape. It is composed of three layers, each with a specific function. The first determines the common node of the sensors, the second provides their output signals, and the third provides electrical insulation. Following this, a vibration motor array was constructed with which various forms of modulation were tested for subsequent temperature interpretation. Time modulation stood out with respect to PWM and frequency modulation, since it allows to better identify the location of the motors and from the duration of their vibration, the temperature level. To establish the relationship between the temperature sensors and the actuators (vibration motors), a circuit capable of identifying the temperature that affects the sensor from its resistance was designed and implemented. Finally, a prototype was built that integrates the electronic skin, the printed circuits and a glove designed to contain the actuator network. Additionally, it has a battery system to make it portable. The tests on three users provide satisfactory results, since after training the lowest percentage of success in the identification of the highest temperature point was 83.3%, and in the pulse duration test to identify 5 specific temperatures the maximum error was 2 °C.