Transcript BATES_uvi_sensor_wire15-eng.vers (315 Downloads)

UVI Sensor
A device
for
real-time measurements
of
UV Index
Dr. Alan Bates
Department of Mathematics, Natural Science and Computer Science
John Cabot University
Via della Lungara 233
00165 Rome, Italy
Why measure UVI?
 Skin cancers rates are increasing significantly since
1970s particularly among fair-skinned people (+4%
per year in the US)
 Skin aging is accelerated with increased exposure to
UV
 Strong reflection from surfaces (sand, water and snow)
can cause damage to the eyelids and eyeball tissues
 Level of awareness of the potential risks of UV
exposure is generally low
WHO Protection Scheme
Recommended sun protection scheme
Calculating UVI
Eλ is the solar spectral irradiance (measure of solar
spectrum transmitted through atmosphere) – varies by
day, season and latitude. Can be measured with a
spectrometer
Ser(λ) is the erythema reference action spectrum for
human fair skin. ker is a constant equal to 40 m2/W
UVA (315–400 nm); UVB (280–315 nm); UVC (100–
280 nm)
Existing UV sensors
ML8511 (Lapis Semiconductor)
 The sensor outputs an analog voltage that is linearly
related to the overall UV intensity, 280-390 nm
 The output is a summation of contributions from all
UV wavelengths - a type of average value
 Advantages: fast real-time measurements; small in
size; requires little power
 Disadvantage: approximate value of UVI
Si1132 (Silicon Labs)
 Sensor measures visible and IR intensities
 Algorithm calculates UV index
 Advantages: fast real-time measurements; small in
size; requires little power
 Disadvantage: +/- 1 difference compared to actual UV
index
The Idea!
Accurate calibration under various atmospheric conditions/UVI values is re
 Notice for both sensors the UVI values are
approximate
 We need a fast and accurate measurement of the UVI
 Utilize UV spectrometer to measure actual real-time
UVI values under various conditions (UV
spectrometers are expensive)
 Simultaneously record output from the ML8511 with
the Arduino microcontroller
 Write algorithm to relate ML8511 output to actual
UVI value in real-time under a wide range of
atmospheric conditions
Displaying UVI
UVI values on a LCD display with WHO
recommendations
Light with colors corresponding to WHO
recommendations
for
Sound alarm if UV Index is above a certain value,
example index 8 or above
Online internet site
2 Sensor Types
 Wall-mounted for
public display in
schools, outdoor
workplaces and public
institutions involving
outdoor work to
communicate UV Index
 Wearable to fit on
clothing to measure
personal UV Index
UVI Network
Connect
 Sensor connected to
internet to stream live
data to online map
 Updated every minute
 Accurate measurement
of UV Index across
country, regions and
provinces
Real-time measurement
Grazie!