Microfluidic ELISA for sensing of prostate cancer biomarkers using integrated a-Si:H p-i-n photodiodes

The accurate detection of prostate cancer (PCa) biomarkers demands improvements in both prognosis as well as diagnosis of the emerging disease. In this work, we propose the use of an immunoassay platform using polydimethylsiloxane (PDMS)-based microfluidics, with integrated optical detection based on an array of miniaturized thin-film hydrogenated amorphous silicon (a-Si:H) p-i-n photodetectors on a glass substrate. This lab-on-a-chip is compatible with fluorescence, chemiluminescence as well as colorimetric modes of detection. We present here sensing of the free isoform of prostate specific antigen (PSA) with labeled antibodies using all the three detection modes. The combination of microfluidic ELISA based on a sandwich assay and the photodiode detection can be extended, with appropriate amplification strategies, as a point-of-care tool for the multiplexing of diverse biomarkers for PCa that are often found at extremely low levels in a pathological condition and hence challenging to detect using routine bioanalytical methods.