correlation between near infrared spectroscopy and electrical techniques in measuring skin moisture...
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Correlation between near infrared spectroscopy and electrical techniques in measuring skin moisture content
By: Mastura Mohamad
Supervisor: Prof. Dr. Mohd Zubir Mat JafriCo-Supervisor: Dr. Ahmad Fairuz Omar
School of PhysicsUniversiti Sains Malaysia
11800 USM, Penang, MalaysiaTel : 604-6533888 Fax : 604-6579150
Motivation of Study
Background of Study
Conclusion
Instrumentation & Experimental Methodology
Result & Discussion
Research Contribution
OUTLINE
MOTIVATION OF STUDY
•Moisture in skin plays an important role to keep skin soft and supple as well as maintaining healthy skin. •A healthy skin has water in stratum corneum (SC) normally around 20% .•Much attention has been paid in evaluating the water content of the SC over the last decade.•The bioengineering provides a non-invasive technique to measure moisture content of skin in vivo with the most popular technique based on measuring electrical properties on skin surface. However, this technique has some limitation.
•Nowadays, NIR spectroscopy technique serves as an important tool for the measurement of moisture content of skin owing to the advantages it has over the other techniques. •The aim of this study to develop a correlation between NIR spectroscopy (NIRQuest) with conventional electrical technique (Dermalab Moisture Module and Scalar Moisture Checker) for skin moisture measurement.
BACKGROUND OF STUDY
What is Skin?Skin is the largest organ of the human body and make up approximately 16% of total body weight.
Skin Layer : Epidermis Dermis Subcutaneous Tissue
Major role : To prevent loss of water and
regulates body temperature by blood flow & evaporation of sweat.
Act as physical barrier to the hostile external environment.
• The epidermis-outer layer of skin.
• The epidermis contains of 5 layers:
Stratum Corneum Stratum Lucidum Stratum Granulosum Stratum Spinosum Stratum Basale
• Stratum corneum (SC) - Outermost layer, thickness 10-20 µm
• The SC functions: Maintaining life - water holding
capacity and lipid content. As a barrier to water loss and
keep skin surface smooth and soft by binding the water
Dry atmosphere - act as a skin barrier to protect the underlying hydrated living skin tissue from desiccation.
Normal skin - water content about 10-20 % near the SC surface.
• The water content of SC is an important physiological parameter indicating skin condition.
Xerosis (Dry skin)
Electrical Technique• The most popular technique to
determine water content of skin is based on measuring electrical properties such as capacitance and alternating current conductivity on the skin surface (Arimoto et. al, 2005).
• Probes have two electrodes of various designs and when it is applied to the skin, the instruments are used to record the value of capacitance or conductance correlate directly with the water content of the skin.
Dermalab (Cortex Technology)
Corneometer (Courage & Khazaka)
NIR Spectroscopy
What is the special about the waves NIR ranges?• NIR light is absorbed by the molecules containing C-
H, O-H and N-H groups.• O-H bands of water are very intensive which exhibit
five absorption maxima at 760, 970, 1190, 1450, 1900 nm (Reich, 2005).
NIR range: 750 -2500 nm
• Electromagnetic spectrum
The stability in changes of temperature
and RH
High in accuracy and
precision
Non occlusive
High sensitivity to
hydrogen bonding
Fast data collection (0.1 s per single spectrum) - with single spectrum allow several parameter determined simultaneously
ADVANTAGES OF NIR SPECTROSCOPY FOR SKIN MOISTURE MEASUREMENT
INSTRUMENTATION AND EXPERIMENTAL METHODOLOGY
Skin Analysis System
•Based on measuring capacitance of SC • Accurate correlation with actual moisture content• Measurement: ranging from 0 to 99.9 %•Unit : percentage (%).
Scalar Moisture Checker MY-808S (Scalar Corporation, Japan)
•Electrical conductance based device •Operating at single frequency 100 kHz• Measurement: ranging from 0-1999 μS •Unit : microSiemens (μS)
DermaLab Moisture Module (Cortex Technology, Hadsund, Denmark)
Reading of Measurement
Moisture Probe
NIRQuest (Ocean Optics)
• High sensitivity optical bench and low noise and dark current.
• Wavelength range: 900nm – 2500nm
• Detector : high performance InGaAs array detector
NIR Spectroscopy Instruments• Light source :
HL-2000 tungsten halogen lamp (wavelength region 360-2500 nm)
• Reflectance probe: R600-7-VIS-125F (wavelength 400-2500 nm)
Human Subjects
10 healthy volunteers (male &
female )
Age : 21- 25 years
Area: Left&right (palm, uppear
arm,forearm,cheek) & forehead
Subject-acclimatized at least 20 minutes in a
temperature-controlled room
Approved by The Human Research Ethics
Committee, USM
Skin self evaluation
Non invasive measurement of skin hydration using NIR spectrometer and
Electrical instruments
Analysis: Minitab 16 Statistical and Unscrambler X 10.3 (trial version) software
For each measurement, a 2 cm x 2 cm test site was applied with three replicated measurements
Methodology
Skin Moisture Measurement Methodology
Measurement techniques of moisture content of skin using conventional electrical instruments.
Experimental setup for skin moisture measurement using NIR spectroscopy technique.
Temperature and humidity sensor
NIRQuest spectrometer
Tungsten halogen lamp
White reference
Fiber optic probe
RESULT AND DISCUSSION
900 1100 1300 1500 1700 1900 2100 2300 25000
10
20
30
40
50
60
70
80
Cheek L
Palm R
Palm L
Forearm R
Forearm L
Upper arm R
Upper arm L
Forehead
Cheek R
Wavelength (nm)
Ref
lect
ance
(%)
Reflectance Spectra of nine different parts of hand and face using NIRQuest spectrometer (Ocean Optics)
1900 nm1450 nm
1190 nm
970 nm
Summary of the experimental results conducted on a skin sample of 10 subjects using a combination of four selected wavelengths (950-970 nm, 1100-1900 nm, 1400-1450 nm and 1870-1900 nm).
SubjectsCoefficient of determination, R2 (%)
NIRQuest &Dermalab
NIRQuest & Moisture Checker
1 77.2 80.1
2 70.9 58.8
3 95.2 56.3
4 96.5 94.4
5 91.7 81.6
6 95.0 51.6
7 81.5 67.3
8 97.9 74.5
9 93.4 90.3
10 88.3 74.1
Average 88.8 72.9
• From the experimental data summarized in the table, moisture content of skin determined by NIR spectroscopy technique correlated well with the electrical conventional techniques with the R2 values range from 70.9 to 97.9 % (average of 88.8 %) between NIRQuest and Dermalab moisture probe.
• Least accuracy has been observed for the correlation between NIRQuest and Moisture Checker with the R2 values ranges from 51.6 to 94.4 % (average of 72.9 %).
The scatter plot graph for the best correlation obtained between the value of (a) NIRQuest &Dermalab (b) NIRQuest & Moisture Checker
a b
25020015010050
250
200
150
100
50
Actual Moisture
Calc
ula
ted M
ois
ture
R2 =97.9 % R2 =94.4 %
CONCLUSION
• A skin-self evaluation questionnaire was conducted and a non invasive measurement were performed on the left and right of the palm, forearm, upper arm and cheek also on the forehead.
• The four ranges of wavelengths 950-990 nm, 1110-1190 nm, 1400-1450 nm and 1870-1900 nm were identified to be strongly dominated by the absorption of water and have contributed very well in the development of correlation between spectroscopic and conventional electrical technique.
RESEARCH CONTRIBUTION
• A correlation of spectroscopic techniques was successfully developed for quantifying moisture content of human skin.
• From the analysis of the entire research confirmed the ability of spectroscopic technique for practically used in quantifying moisture content of human skin.
• Therefore, can help to establish novel specialized optical system for rapid and non-occlusive measurement in clinical used especially in the dermatology field.
THANK YOU FOR LISTENING
School of PhysicsUniversiti Sains Malaysia