All silk-screen printed polymer-based remotely readable temperature sensor

In this paper, we present the fabrication and characterization results of a remotely readable flexible temperature sensor. The sensor has been fabricated with screen printing technology and it consists of a polymer-based capacitor (ASAHI CR18-KTI polymer paste) as a temperature sensitive component added to the antenna coil (ASAHI LS411-AW silver paste) for remote reading purposes. The resonance frequency of the sensor (i.e. the formed LC network) is measured as a function of temperature. The sensor has been characterized in the temperature range of 0 °C-70 °C and the total sensitivity over this range is ∼ 9 kHz/°C. The sensor's normalized temperature response is independent from the polymer capacitor's thickness and the effective capacitor area, which enables reasonable performance despite fabrication process induced inaccuracies. Due to the inexact nature of the resonance peak measurement, a data-analysis algorithm was developed to enhance the accuracy of the measurement method. In addition, the sensor response to the misaligned reader and the sensor self-heating effect, due to the inductive excitation voltage, are considered. Finally, the calibration of such a sensor is discussed.