We have developed a tactile stimulation system that can apply air puffs locally to any two points on a skin's surface. This system consists of an air output device and a reaction recording device, both controlled by dedicated software. The air output device is equipped with a microcontroller ESP32, which can produce an airflow from two ports by controlling the intensity of the compressed air, the duration of its output, and the inter-trial time interval between applications. The reaction recording device is equipped with a push-button to record the subject’s response when the air is applied to the skin. We verified the applicability of this system by a two-point discrimination test. In 14 healthy human subjects, the shortest distance at which they correctly answered that the given air at two points was 35 mm. When we applied the air at 30 mm, majority of the human subjects answered incorrectly that the air was at one point when in fact it was two points. This result was in close agreement with previously reported results obtained by direct skin stimulation methods.

Here, we report a novel biosensing system using a finger-powered microfluidic device, which is suitable for daily self-testing of uric acid in saliva. To realize the rapid determination of salivary uric acid, the biosensing system measures directly from the paper-based saliva sampling device. The microfluidic device has the diaphragm pump, the reagent reservoir, and the reaction cell in which the electrochemical uric acid biosensor is embedded. Once the microfluidic chip has been folded, the finger-powered microfluidic device prepares the reagent containing the saliva, which is ready to measure. A wireless potentiostat for electrochemical measurement of uric acid with the biosensor was also developed. Combining these elements together, the whole process from saliva sampling to determination was completed in less than a minute (Sensitivity: 0.03 nA/µM). The measurement results were also consistent with that measured using a commercially available uric acid determination kit. Hence, our method is expected to have the potential to enhance the use of biochemical information in the field of healthcare IoT.

Polydimethylsiloxane (PDMS)-based microfluidic devices are widely used for biomedical applications. Their large-scale commercial realization demands the standardization of PDMS microchips. However, the outer shape of chips has been difficult to shape with a single mold on a flat substrate. This paper reports the combinational use of an upper stacked mold and a lower fine mold for making standardized microchips. We employed a laser-cutting service to make a roughly designed mold cost-effectively. PDMS was cured using the lower and upper molds and chips were released from the molds. The fine pattern of the lower mold and the outline pattern of the upper mold were successfully transferred to the PDMS chips. Our technology has saved time and labor for forming a standardized microchip and increasing the productivity of microchip.