UV amount measurement without battery, system mechanism developed by Ritsumeikan University | New Switch by Nikkan Kogyo Shimbun

A research group led by Professor Takakuni Doseki of Ritsumeikan University has developed a system that can measure the amount of ultraviolet rays (UV) in sunlight in real time without a battery. As a wearable sensor device that can be worn on clothes and hats, it is expected to be applied in the fields of beauty and healthcare. With a unique power supply circuit configuration that uses a single solar cell and a photodiode, real-time hands-free measurement, which was a problem with conventional batteryless UV sensors, becomes possible.

The new batteryless UV sensor system can measure the amount of "UV-A" and "B" that can cause stains, wrinkles, skin cancer, etc. when the human body is exposed to it for a long time. The measurement data is transmitted to a smartphone or the like by low power consumption short-range wireless communication "Bluetooth Low Energy (BLE)".

The power generated by the solar cell is controlled by the input regulator so that the power supply voltage of the sensor circuit becomes constant, and the power generation current is supplied to the sensor circuit while the rest is charged to the storage capacitor. When the sensing capacitor of the sensor circuit is charged, no current is sent to the radio and it is discharged to the ground (GND), and when the charging is completed, the power of the storage capacitor is supplied to the radio. The UV sensing amount is detected at the wireless signal interval.

The conventional batteryless UV sensor uses the short-range wireless communication "NFC", and it is necessary to bring the smartphone and the device close to each other at the time of measurement. In addition, it lacked the real-time property of being able to measure only the total amount of UV and knowing when and how much UV was exposed.

In the future, we will utilize the new system and consider developing a system that sounds a warning sound from a smartphone when the amount of UV exceeds a certain value in collaboration with beauty and healthcare related companies and system development companies.

Nikkan Kogyo Shimbun November 5, 2021