Real Time Cytokine Quantification in Wound Fluid Samples Using Nanowell Impedance Sensing

Cytokine levels in skin wound fluid can provide valuable information on the progression of the local healing phases and help in making therapeutic decisions. The gold standard cytokine quantification method is the enzyme-linked immunosorbent assay (ELISA), which typically relies on labeling and an optical read-out. Impedance sensors provide a promising alternative whose advantages include ease of miniaturization, rapid readout, and label-free operation. We present a nanowell impedance sensor for label free cytokine quantification in wound fluid samples. The sensor relies on the nanowell array structure to perform the label free cytokine detection with high sensitivity despite the high salt concentration of wound fluid. Real time cytokine detection is achieved in the experiments by continuous monitoring of the impedance of the sensor using lock-in amplifier, which increases due to the target protein binding. Multiplexing measurements are also achieved using a multiplexer chip in conjunction with an embedded microprocessor.