Automatic Biochemical Molecular Collection And Detection By Microengine-based System

The manipulation and detection of molecules on a micro-chip is of great interest in bioanalysis,optofluidics and lab-on-a chip research,aiming at simplification,reduction of costs,and ease of reproducibility.Particular attention has been given to on-chip surface-enhanced Raman scattering(SERS),which is capable of’fingerprinting’ materials from very small volumes,making it suitable for analysis on the microchip size scale.However,the high cost and the complexity of additional manipulation components are motivating and stimulating new routes and principles for practical integrated microchips.We design and fabricate a simple self-powered system to collect analyte molecules in fluids for SERS detection.The system is based on catalytic microengines by employing rolled-up nanotechnology.Such a molecule collection and detection system could extend the scope of applications for bioanalysis and lab on-a-chip towards new designing routes.The main results are outlined as follows:1.Tubular catalytic microengines based on Au/SiO/Ti/Ag-layered microtubes are fabricated by employing polymer-based rolled-up nanotechnology.This material combination is selected based on the desire for different functions.Standard photolithography or shadow mask method is employed to pattern the nanomembranes into well-defined shape.We introduce etching agent in a specific location to roll up nanomembranes directionally.The diameter of microengine is tuned by changing the nanomembrane thickness.Besides,the surface nanostructure of microengine can be tuned by changing the substrate.2.The microengine shows excellent SERS characteristic itself,owing to gold and the surface nanostructures.A finite-difference time-domain method was employed to illustrate the excitation of the localized surface plasmon modes by calculating the electromagnetic field on the microengine surface,which shows that maximum local enhancement is as large as 105 in the V-shaped gaps.The SERS property of microengine can be tuned by changing the gold layer thickness and covering gain medium.3.We investigate the motion behavior of microengines by changing parameters such as fuel concentration.About fivefold SERS signals are observed on microengines with more carrier molecules compared with the same structure operated in the traditional method.These results clearly indicate that active microengines serve as effective carriers of analyte molecules,making a contribution to extending the molecule adsorption path and increasing the capture probability.Furthermore,these automatic microengines can swim to a specific area to perform non-contact detection,which has a promising prospect.