Summary of ULTRAV: A PORTABLE UV-INDEX METER
UltraV is a portable UV-index meter built on an Arduino Nano rev3. Using an ML8511 UV sensor, an MT3608 DC-DC step-up to boost a CR2 battery, and a 128×64 SSD1306 OLED display, the device reports UV intensity for on-the-go use. The ML8511 provides an amplified analog voltage proportional to UV-A and UV-B, with very low standby current. The builder left the sensor exposed because common transparent covers attenuated UV; fused quartz would be ideal but was unavailable.
Parts used in the UltraV:
- Arduino Nano rev.3
- ML8511 UV sensor
- 128×64 OLED display (SSD1306)
- MT3608 DC-DC step-up converter
- CR2 battery
- CR2 battery holder
- switch
- enclosure case
Being unable to expose myself to the sun due to a dermatological problem, I used the time I would have spent on the beach to build an ultraviolet rays meter. UltraV.
It is built on an Arduino Nano rev3, with an UV sensor, a DC/DC converter to raise the 3v battery voltage, and a small OLED display. My main target was to keep it portable, so that I could easily know the UV-index in any moment and in any place.
Step 1: Parts and Components
- Microcontroller Arduino Nano rev.3
- ML8511 UV sensor
- 128×64 OLED diplay (SSD1306)
- MT3608 DC-DC step-up
- CR2 battery
- CR2 battery holder
- switch
- enclosure case
Step 2: The Sensor
The ML8511 (Lapis Semiconductors) is an UV sensor, which is suitable for acquiring UV intensity indoors or outdoors. The ML8511 is equipped with an internal amplifier, which converts photo-current to voltage depending on the UV intensity. This unique feature offers an easy interface to external circuits such as ADC. In the power down mode, typical standby current is 0.1µA, thus enabling a longer battery life.
Features:
- Photodiode sensitive to UV-A and UV-B
- Embedded operational amplifier
- Analog voltage output
- Low supply current (300µA typ.) and low standby current (0.1µA typ.)
- Small and thin surface mount package (4.0mm x 3.7mm x 0.73mm, 12-pin ceramic QFN)
Unfortunately, I didn’t have the chance to find any UV-transparent material to protect the sensor. Any kind of transparent cover I tested (plastic, glass, etc.) was attenuating the UV measurement. The better choice seems to be quartz fused silica glass, but I haven’t find any at a reasonable price, so I decided to leave the sensor outside the box, in open air.
Read more: ULTRAV: A PORTABLE UV-INDEX METER
- What microcontroller is used in UltraV?
The project uses an Arduino Nano rev.3. - Which sensor measures UV in UltraV?
The ML8511 UV sensor is used to measure UV-A and UV-B. - How is the battery voltage raised for the circuit?
An MT3608 DC-DC step-up converter is used to raise the CR2 battery voltage. - What display is used to show the UV-index?
A 128×64 OLED display with the SSD1306 driver is used. - Is the UV sensor enclosed in the case?
No, the sensor was left outside the box in open air because common transparent covers attenuated UV measurements. - Why was fused quartz glass suggested for the sensor cover?
Fused quartz glass transmits UV with less attenuation, but it was not found at a reasonable price. - Does the ML8511 provide a digital output?
The ML8511 provides an analog voltage output proportional to UV intensity. - Does the ML8511 support low power modes?
Yes, it has a power down mode with a typical standby current of 0.1 µA.
