Development of a microfluidic electrochemical biosensor: Prospect for point-of-care cholesterol monitoring

Microfluidic devices offer a number of merits including reduced sample volume, fast turnaround time and highly sensitive real time measurements for lab-on-a-chip technology. Thus, we report the development of a microfluidic electrochemical biosensor for cholesterol monitoring. PDMS microchannels of dimensions 300 μm(w) x 40 μm(h) x 1 cm(l) have been fabricated using SU8 photolithography and replica molding technique. For the biosensing chip, platinum electrodes were fabricated by conventional photolithography process. The working electrode was modified by nickel oxide (NiO) thin film deposited using sputtering technique while bare platinum thin film served as the counter electrode. The microchannels were reversibly sealed with the chip by conformal contact. Cholesterol oxidase enzyme, immobilized over the NiO thin film, was employed as the specific bioreceptor for cholesterol. Highly sensitive detection of cholesterol in a wide range of concentration (0.12-10.23 mM) with a low detection limit of 0.10 mM was achieved using the fabricated microfluidic amperometric biosensor, thus demonstrating its ability for point-of-care diagnostics.