Volumetric bar-chart chips for biosensing

The volumetric bar-chart chip (V-Chip) is a microfluidics-based, point-of-care (POC) device for the multiplexed and quantitative measurement of biomarkers. Volumetric readouts, based on the measurement of oxygen generated by a reaction between catalase and hydrogen peroxide, allow instant visual quantitation of target biomarkers and provide visualized bar charts without any assistance from instruments and without the need for data processing or graphics plotting. V-Chip shows potential capabilities in POC and personalized diagnostics; for instance, it can be utilized for making high-throughput, multiplexed, and quantitative measurements. Further, this system is highly portable and can be performed at low cost. The development of the V-Chip thus marks a POC milestone and opens up the possibility of instrument-free personalized diagnostics. Here, we describe the protocols for the fabrication of V-Chip and the use of silica nanoparticles as the probe carrier for the V-Chip-based enzyme-linked immunosorbent assay (ELISA) for the detection of biomarkers.