Visualization of enzymatic reaction in a microfluidic channel using chemical imaging sensor

The chemical imaging sensor is a semiconductor-based chemical sensor which is capable of visualizing the spatial distribution of chemical species. In this study, we applied the chemical imaging sensor to a dye-free method of visualizing an enzymatic reaction in a microfluidic channel. Microgel beads loaded with enzyme molecules were trapped in the microchannel. The substrate of the enzyme was injected from the upstream, and then the product of enzymatic reaction was detected in the downstream as pH change. The spatiotemporal change of pH distribution caused by the enzymatic reaction was successfully visualized. The possibility of chemical imaging inside a microchannel also suggests potential application, for example, to chromatography.