Study of Microfluidic Chip Integrated with Thermosensitive Flexible Sheet and its Application for the Detection Bacteria on the Surface of Objects

Abstract

A microfluidic chip integrated with thermosensitive flexible sheet was proposed to efficiently detect bacteria on the surface of objects, which has the functions of sampling, transfer, concentration and detection of bacteria. It could potentially be used to address the problems of the complex and separate operations between sampling and detection, low transfer efficiency and low detection efficiency. The microchip was composed of a flexible sheet with poly (N-isopropylacrylamide) (PNIPAAm) gel micropillar array and a PDMS cover sheet containing a canopy-shaped microchannel. The thermosensitive PNIPAAm gel micropillar array with high specific surface area and unique properties of adhesion-release to bacteria was adopted for the efficient sampling and release the bacteria. The released bacteria were transferred and labeled in the canopy-shaped microchannel, and then the labeled bacteria were concentrated and detected in-situ on the microchip. Under the optimized experimental conditions, the sampling and the elution efficiency of S. aureus on stainless steel sheet could be up to 75.6% and 88.4%, respectively. The detection limit of S. aureus was 5.15×103 CFU/cm2, and the whole process took no more than 45 min. The established detection method with the designed microchip has potential applications in the efficient detection of bacteria on the surface of objects.

Keywords: microfluidic chip, flexible sheet, poly (N-isopropylacrylamide) gel, sampling of bacteria on the surface of objects, Fluorescence detection