Abstract
We developed a novel sensing method to measure the local environment using functional gel-tool in the microchip. We achieved active sensing by laser tweezers. We used salting-out gel-tools impregnated with Bromothymol Blue (BTB), which is a pH indicator. The salting-out gel-tool is made of ENT-3400, which is hydrophilic photo-crosslinkable resin, and high concentrations of electrolytic solution. We can measure pH value locally from the color of gel-tool using calibrated color information in YCrCb color space. Gel-tools are cured by UV-ray and adhere to the glass and another gel. We can manipulate the gel-tools by laser tweezers, because the refraction index is higher than water. However, the target to be measured nearby by the laser trapped gel-tool may be sucked in the focal point of laser. Therefore, we assembled a microprobe with gel-tools to avoid such interference. As parts of the microprobe, we made square pillars by photolithography with SU8 photoresist and assembled a microprobe with a gel-tool. We succeeded in measuring local pH value with the pH sensing probe at the desired point.
