Assessment of Frying Oil Degradation using Laser Direct Writing Interdigital Sensors

The repeated usage of frying oil is proven to be unhealthy because the chemical reactions that occurs in the oil degrades the oil quality and creates high molecular weight and complicated structure saturated compounds which are harmful to human health. A series of interdigital sensors with different electrode width and interelectrode space are designed and produced by the laser direct writing ablation technique to evaluate the vegetable oil quality in regards to usage days. The sensor with 100 pm electrode width and interelectrode space could detect the change of frying oil over time using the LCR meter with scanning ranges of 20 Hz to 10 MHz. The LCR meter can monitor the absolute value of impedance and phase angle. The higher applied voltage for the sensor, the larger the response impedance signals. However, sensors with 300 pm and 500 pm electrode width and interelectrode space did not receive significant signals and functioned as a regular capacitance gauge because of the small magnitude changed signals embedded in the large magnitude of impedance values.