A Label-Free Low-Cost Radio Frequency Driven Noninvasive Lab-on-Chip System for Creatinine Detection

This paper illustrates a label-free, low-cost, fast detection of creatinine using a noninvasive lab-on-a-chip (LoC) Interdigitated capacitor (IDC) based sensor. Creatinine is a metabolic product of creatine phosphate in muscles, which provides energy to muscle tissues. The detection is done on an IDC made of copper (Cu) metal over an FR4 substrate. The sensor has been designed using a high-frequency structure simulator (HFSS) tool. Then the design is fabricated over the FR4 printed circuit board (PCB) and tested using a Vector Network Analyzer (VNA). The creatinine sample under the test is confined using a Polylactic Acid (PLA) wall attached to the sensor. A 52 MHz difference is observed between the simulated and experimental operating frequencies. The principal idea implemented in the biosensor design is to track the shift in the operating frequency in the presence of different concentrations of creatinine diluted in water and compare it with the operating frequency of the sensor with water as a reference. The testing is done in the medical range of 0.5 mg/dL to 2 mg/dL of creatinine solution.