Post on 01-Jan-2016
description
transcript
Hair Hydration Measurements Using Opto-thermal Radiometry and AquaFlux
aFaculty of ESBE, London South Bank University, 103 Borough Road, London SE1 0AA, UK
bBiox Systems Ltd, 103 Borough Road, London SE1 0AA, UK
Perry Xiaoab and RE Imhofb
Opto-Thermal Transient Emission Radiometry (OTTER)
Pulsed Laser ExcitationPulsed Laser Excitation Infrared Emission SignalInfrared Emission Signal
SampleSample
tt tt
9.5µm9.5µm13.1µm13.1µm
Heat
AirAir
Thermal diffusivity, D (m2s-1)
Absorption coefficient to excitation light, (m-1)
Absorption coefficient to emission light, (m-1)
Layer structure
Opto-Thermal Skin Measurements
Opto-Thermal Delayed Thermal Wave (DTW) Measurements
Opto-thermal delay time t=L2/(D)
L : Epidermis thickness
D: Epidermis thermal diffusivity
SkinSkin
Stratum Stratum
CorneumCorneum
EpidermisEpidermis
DermisDermis
Heat absorbed byHeat absorbed by
melanin &melanin &
HaemoglobinHaemoglobin
LL
OPO Laser
420 ~ 590nm
Thermal Delayed Signal
AirAirTime /ms
Inte
ns
ity
/a
rb A
C
B
Time /ms
Inte
ns
ity
/a
rb A
C
B
Opto-Thermal Skin Measurements
Infrared Infrared Emission SignalEmission Signal
Er:YAG 2.94µmEr:YAG 2.94µm
Stratum Stratum CorneumCorneum
EpidermisEpidermis
DermisDermis
Heat absorbed byHeat absorbed bywaterwater
AirAir
SkinSkin
S t Ae erfc tt( ) //
Opto-Thermal Skin Measurements
Stratum CorneumStratum Corneum EpidermisEpidermis
HydrationHydration HydrationHydration
Stratum CorneumStratum Corneum EpidermisEpidermis airair
HH00
HH00
HH11
LL
S t A
W t
Wt
Wte erfc
t
Wt
t
Wt
( )( )
( )(
/)
/
2
2 1
1
2 1 2 132 1
S t A e erfc tt( ) ( / )/
1 2/ D 1 0
2/ D W wD
Uniform Model Gradient ModelUniform Model Gradient Model
Opto-Thermal Skin Measurements
1 2 3 4 5 6 7 8 9 10 11 12a
b
c0
0.2
0.4
0.6
0.8
1
1.2
1.4
Surface Lifetime
/ms
Row
1.2-1.4
1-1.2
0.8-1
0.6-0.8
0.4-0.6
0.2-0.4
0-0.2Wrist
Elbow
1 2 3 4 5 6 7 8 9 10 11 12a
b
c0
200
400
600
800
1000
1200
1400
1600
Effective Gradient
/s-1
Row
1400-1600
1200-1400
1000-1200
800-1000
600-800
400-600
200-400
0-200Wrist
Elbow
12
34
56
78
910
1112
a
b
c
0
10
20
30
40
50
60
70
Th
ick
ne
ss
/µ
m
Row
60-70
50-60
40-50
30-40
20-30
10-20
0-10
Elbow
Wrist
Opto-Thermal Measurements
0 0.2 0.4 0.6 0.8 1
0.2
0.4
0.6
0.8
1
S t
t
S t t / m
Z te z z t dz
e z t dz
z
z( )
( , )
( , )
0
0
Opto-Thermal Measurements
S t Ae erfc tt( ) //
Traditional Least-Squares Fitting Segmented Least-Squares Fitting
Opto-Thermal Measurements
( )z
S t( )
Z tt
e erfc t
t
t( )
22
Time
Depth
1
1
0
Transform Function
( )( )
zt D
1
Opto-Thermal Hair Measurements
Opto-Thermal Hair Measurements
Opto-Thermal Hair Measurements
Opto-Thermal Hair Measurements
Opto-Thermal Hair Measurements
Condenser TEWL Method -AquaFlux
Condenser based, Closed-Chamber TEWL Measurements Technology
Condenser-7.65 °C
RH and Temperature Sensors
Sample
Ice
TEWL – Trans - Epidermal Water LossTOWL – Trans - Onychial Water Loss
TEWL and TOWL Measurements
TEWLV
ambambskinV
JJ
TRHTHBfJ
),,,,( 0
Stratum CorneumStratum Corneum EpidermiEpidermiss
HydrationHydration
airair
HH00
HH11
LL
WW
Jv JTEWL
z
HDJTEWL
Hair Desorption
Hair Desorption
Hair Desorption
Hair Desorption
Conclusions
•The results show that OTTER can be used to measure the water concentration and water diffusion within hair samples. OTTER signals can reflect the layered structure of hair, the water concentration depth profiles show that within hair water might not distributed uniformly. Hair samples appeared to be able to absorb a lot of water during 10 minutes soaking, and to hold on most of it during the next 20 minutes period.
•AquaFlux can be used for measuring the water holding capability of ex-vivo hair samples through natural desorption process. The results show that different hairs have quite different desorption processes which are likely indicating different water holding capabilities. By fitting the desorption curves with suitable mathematical models we can also extract the water diffusion coefficients of hair.
Acknowledgements
We thank London South Bank University and EPSRC for the financial support.