Saw-Toothed Microstructure-Based Flexible Pressure Sensor as the Signal Readout for Point-of-Care Immunoassay

A saw-toothed microstructure-based flexible pressure sensor was designed as the signal readout for point-of-care (POC) immunoassay of carcinoembryonic antigen (CEA). In this portable POC bioassay, the sandwich-type immunoreaction was first carried out to capture the target on a microplate, which simultaneously introduced the platinum nanoparticles (PtNPs). Upon adding hydrogen peroxide (H₂O₂), the pressure as the bridge between the molecular recognition event and detectable signal was increasing rapidly, resulting from the decomposition of H₂O₂ accelerated by PtNPs. Meanwhile, a flexible pressure sensor was fabricated with high sensitivity; the ability of the pressure response was dramatically improved by adopting the saw-toothed microstructure. By coupling with the pressure sensor, the pressure change could be monitored in real time to achieve the portable detection of CEA. Under the optimum conditions, the proposed pressure-based bioassay presented good sensing performance within 0.1-40 ng/mL at a detection limit of 87 pg/mL. The reproducibility, precision, and accuracy provided by the method were also studied and satisfied.