Nitride photodetectors
in UV biologicaleffect studies
Elias Muñoz
INSTITUTE FOR SYSTEMS BASED ON
OPTOELECTRONICS AND MICROTECHNOLOGY
Universidad Politécnica de Madrid (UPM)
http://www.isom.upm.es
Outline
a) Solar UV radiation
•
•
•
•
Ozone and UV radiation
UV biological action spectra
Erythema (red skin)
Life adapted to ozone absorption (DNA damage/repair)
b) UV and biophotonics
•
•
•
fluorescence (dyes, fluorescent-proteins, microspheres)
Quantum dots as fluorescent markers
Lab-on-a-chip
c) Nitride-III photodetectors
•
•
•
Bio Action Spectrum detectors. Erythema detectors
AlGaN detectors
Materials and processing issues. Problem areas
•
Conclusions
Solar UV radiation
Solar UV radiation
(Photoactinic
radiation)
(%)
Ozone absorption
Ozone
absorption
250nm
wavelength nm
Ozone and UV radiation
The ozone hole
Antartic station
03~3 mm = 300 Dobson units
Ozone depletion and UVB changes
03~3 mm = 300 Dobson units
Risks and benefits of solar radiation
Risks
• Sunburn
•∙ Suntanning (pigmentation)
•∙ Photoaging
•∙ Skin cancer
•∙ Malignant melanoma
•∙ Local and systemic immune
suppression
•∙ Photosensitivity diseases
•∙ Drug related phototoxic
and photoallergic reactions
•∙ Cataracts
Benefits
• Vitamine D synthesis
• Phototherapy and
photochemiotherapy
• Psychological comforts
UV action spectrum
UV biological action spectra: basics
photosynthesis
PAR
DNA absorption
UV action spectra
•λ
λ<280 nm : bacteria killing (UVC water treatment at 250nm)
biological action spectra
DNA damage in humans
Skin carcinogenesis in humans
Erythema (red skin)
UVB
UVA
UVC
•Bio-complexity (damage and healing, repairing mechanisms)
Solar UVB,...., skin cancer
Minimum erythemal dosis and UV index
RED SKIN
•Weighted erythematic radiation:
from 25 mW/ m2 up to 400 mW/ m2
•Minimum erythema dosis (MED)
for red skin: 210 J/m2
•UV index: 1 to 16
Extreme (>9)
High (7-9)
Moderate (4-7)
Low (<4)
UV radiation and agriculture
Inhibition of photosynthesis by UV illumination
vs. time and UV wavelength
Blue light benefits?
Eye absorption and lamp hazards
LIFE ADAPTED TO UV
•After the BB (t=0) , organisms that
survived to “UV springs” kept
adapting to solar irradiation…to
Earth´s atmosphere
•Natural selection, genetic variants,
repairing enzymes,
•Fur, shells, pigments...protect!
•Flavonoids, in plants;
mycosporinelike aninoacids, in algae,
and sea creatures,
absorb UV (UVB!), protect!
absorption
•ozone absorption<>
<>DNA
<>
•Life adapted! (λ
λ>280nm)
(J. Withgott, Natural History, Jul. 2001, 38)
semiconductor UV bio-frontier
• Life adapted to the UV photons reaching us from the
Sun;
• UVA-λ>320 nm low damage; UVB-280<λ<320
medium damage, and UVC-λ<280 nm high damage
•
UV biophotonics on earth: 280<λ<400 nm
• The region λ<280 (cell/tissue high damage), requiring
higher Al%: bacteria killing, water purification...
• Erythema detectors: weighted standard response for
comparative AS studies
ABSORPTION OF LIGTH BY WATER
•Optical comm.
in water
•Detection of
contaminants
(pesticides,
detergents..)
•Lab
preparations