Microelectromechanical System Based Platforms for Microfluidic and Sensing Applications

Abstract

Emerging microelectromechanical system (MEMS) based platforms show great prospects in bio-MEMS applications recently. Three platforms were proposed and demonstrated based on polymer, paper, and hydrogel substrates for microfluidic and sensing applications.

A size-selective microfluidic platform (ExoSMP) based on polydimethylsiloxane (PDMS) for EV isolation was proposed based on nanomembrane filtration and hydrodynamic properties of the particles. The isolation efficiency was investigated at different sample flow rates and demonstrated a high recovery rate of 94.2% and high reproducibility at an optimal sample flow rate with short processing time. Isolation of EV subpopulations were also demonstrated by altering the pore sizes of membrane filters. ExoSMP shows great potential in investigating the role of EVs in various point-of-care applications in disease monitoring, medical diagnosis, and drug delivery.

A low-cost and enzyme-free paper sensing platform was proposed and developed based on molecular imprinted polyaniline (MIP-PANI) electrode by a one-step synthesis method by co-polymerization of the aniline monomer with the template on paper. The sensing electrode with target binding sites and the signal-transducing electrode were created at the same time by MIP-PANI. Glucose concentration was determined in both aqueous and bovine blood solutions by the impedance change to evaluate the performance of the PANI paper sensors. This simple paper sensing platform provides low-cost and reliable chemical/biomarker analysis access to various applications such as disease diagnostics and environmental monitoring, especially in underserved communities.

A multiplexed barcode hydrogel platform was proposed with four discrete compartments containing two types of oxygen and glucose sensing domains to demonstrate multiplexed optical sensing. The fabrication process was developed and optimized for low-cost and mass production by soft lithography and molding. Multiplexed oxygen and glucose response test were characterized by phosphorescent lifetime change of the sensing assays and it demonstrated minimal crosstalk between the nearby oxygen and glucose responsive compartments. The barcode hydrogel sensors were exposed to 10 consecutive cycles of 0 mg/dL glucose and 200 mg/dL glucose and demonstrated a good glucose response stability. This multiplexed and implantable barcode hydrogel platform has great potential in the diagnosis, monitoring, management, and treatment of various pathological conditions and can be a valuable tool in personalized medicine.