On-Demand Adhesive Control of Functional Gel-Tool for On-Chip Cell Measurement

An on-demand adhesive control of functional gel-tool for on-chip cell experiment was developed. Adhesiveness of the gel-tool was controlled by UV illumination in an electrolyte solution of an adjusted electrolyte concentration. Gel-tool adheres to objects such as glass substrate, other gel-tool and cell by contact to the target object under UV illumination. Without UV illumination, gel-tool does not adhere to objects in the same conditions. Gel-tool is made by salting-out of hydrophilic photo-crosslinkable resin. This gel-tool can be functionalized by introducing functional materials such as indicators. We produced gel-tool impregnated with pH indicator Bromothymol blue (BTB), which is used for neutral range, for measurement of ambient pH value of target cell. The pH sensing gel-tool is manipulated by optical tweezers. The pH value is measured by detecting the color of the gel-tool in calibrated color information. We succeeded in local pH measurement around a single yeast cell by surrounding the cell using ring-shaped gel-tool and by immobilizing the cell on the surface of the pH sensing gel-tool.