Multiwell Plate Impedance Analysis of a Nanowell Array Sensor for Label-Free Detection of Cytokines in Mouse Serum

We present a novel method for label-free detection of tumor necrosis factor alpha (TNF-α) in serum after immobilization by electric field. Detection of proteins in blood using label-free impedance-based techniques is difficult due to high salt concentration of the matrix, which results in charge screening. The nanowell array sensor provides enhanced electrochemical sensitivity by electric field focusing in the nanoscale volume wells. Here, an on-chip multiwell plate sensing platform was fabricated and tested. The sensor performance through testing in mouse serum at protein concentrations between 10 and 500 ng/l has been demonstrated. This detection modality is advantageous to many label-free electronic sensors in that signal power scales will increase in salt concentration, thus improving the sensitivity of the platform.