Feasibility of a Gelatin Temperature Sensor Based on Electrical Capacitance

The innovative use of gelatin as a temperature sensor based on capacitance was studied at a temperature range normally used for meat cooking (20-80 degrees C). Interdigital electrodes coated by gelatin solution and two sensors of different thicknesses (38 and 125 mu m) were studied between 300 MHz and 900 MHz. At 38 mu m, the capacitance was adequately measured, but for 125 mu m the slope capacitance versus temperature curve decreased before 900 MHz due to the electrothermal breakdown between 60 degrees C and 80 degrees C. Thus, for 125 mu m, the capacitance was studied applying 600 MHz. Sensitivity at 38 mu m at 868 MHz (0.045 pF/degrees C) was lower than 125 mu m at 600 MHz (0.14 pF/degrees C), influencing the results in the simulation (temperature range versus time) of meat cooking; at 125 mu m, the sensitivity was greater, mainly during chilling steps. The potential of gelatin as a temperature sensor was demonstrated, and a balance between thickness and frequency should be considered to increase the sensitivity.