non invasive 20blood 20glucose 20 measuring 20system

8/6/2019 Non Invasive 20Blood 20Glucose 20 Measuring 20System

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Non-Invasive Blood Glucose Measuring System

Department of Electronics & ECE

Prof. Swapna Banerjee

n an nst tute o ec no ogy, aragpur


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Diabetes Mellitus

A metabolic disorder in which our body is unable toregulate the level of glucose in the blood

Most prevalent non-communicable disease

More than 150 million diabetic patients in the world


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Management of diabetes

Diabetes related long term complications are leadingcause of death

The complications can be reduced by 50-75% by tighterg ycem c contro

Frequent monitoring Ad ustin the medical nutritional thera , exercise

and medications to prevent hyper- or hypoglycemia

(Source : The Diabetes Control and Complications Trial Research Group, The effect of intensive treatment of diabetes on the develo ment and ro ression of lon terms com lications in insulin-de endent diabetes mellitus N. Engl. J. Med. 329(14), 977-986 (1993))


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Present technique of monitoring blood glucose

Either invasive or minimally invasive

e ng o - ne me o s-Time consumingLabour intensiveMay not reflect real-time status of the glucosecan cause cell contamination


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Shortcomings of invasive method

Painful

High recurring cost

Potential source of spread of diseases like Hepatitis,HIV through contact with bodily fluids

Continuous monitoring not possible


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Why non-invasive method ?

Will remove all shortcomings of present techniquesIm rove ualit of life

Reduce complications and mortality associated withthe disease

Possibility of developing artificial pancreas


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Potential non-invasive optical methods

Infrared and Near-infrared absorption spectroscopy

Near-infrared scattering technique

Polarimetry techniqueRaman spectroscopy


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Photoacoustic MethodM d l d l b

Excited state

Modulated laser beam

AbsorptionRadiativebsorption

p

of lighttransition

Non-radiativetransition

Sampleressure wave

A h A

Ground stateAcoustic transducer

heat A A


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Factors affecting PA generation

Nanosecond PulsedLaser Beam

Skin and Tissue

WavelengthPulse Wid th, PRF

Ei

: Incident optical energya : Absorption coefficientd : Length of the cylinder within the sample

occu ied b the o tical beam

Local Absorptionglucose molecules

RadiativeRelaxation

Flourescence,

Optical absorption coeff. Cp : Specific heat capacity for a constant pressure : Density of the medium

V : Illuminated volume at room temperaturer : Radius of the optical beam

V C d E

T p

aiLocal TemperatureIncrease

Adiabatic

Phosphorescence

Specific heat capacityVol . expansion coeff.

: Volumetric thermal expansion coefficient ofthe medium

T : Rise in temperatureB : Bulk modulus

2

2

.. r

EC

vV C d E

B t B p ai aiPressure Wave

Generation

Speed of sound

v : pee o soun n e me um

/ Bv Transducer type &Dimension

Pressure DetectionTransducer


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Dependence of PA signal on glucoseconcentration

2ai

p

2

rE.

Cvp

More immune to scattering


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Phases of development

The total development process has been planned intwo phases

Phase I

Validation of the technique with glucose solution

Phase II A lication on human sub ect


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- invasive blood glucose monitoring system

Pulse Driver

DIGITAL SIGNAL PROCESSING BLOCKS

Generator Circuit

LaserDiode

PiezoelectricTransducer

Low NoiseAmplifier

na og toDigital

Converter

SignalAverager

Fast FourierTransform

Digital PeakDetector

Disply

Calibration

CorrectionFactors


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System Photograph


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Choice of components

Acoustic signal detectorSensitive

uggeInsensitive to changes in ambient conditions


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Choice of wavelength

905nm905 nm

905 nm wavelength gives desired depth of penetration and absorption by

Water and other constitutes of blood are less compared to glucose.


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Absorption profile of glucose

1

GC

M


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Comparison between 905 nm and 1064 nm

Parameter 905 nm 1064 nm

Absorption in tissue Slightly higher thanat 1064nm

Lower than at905nm

Reduced scattering coefficient Low Almost equal

Effective penetration depth Second highest Highest(2.5mm) (3.5mm)

Absorption in water 0.007 mm -1 0.015mm -1

Absor tion in lucose Low Ver hi h

Sensitivity to oxy-hemoglobinand deoxy-hemoglobin

Less High

ower ou pu o aser o e wa wa


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Optical source and acoustic detector

Optical sourcePulsed Laser diode having = 905 nm

Pulse width : ~100 ns

Pulse repetition frequency : ~100 HzPulse energy : Less than 0.1 J/Sq. cm.

Acoustic DetectorPiezoelectric material (PZT-5A) from Panametrics, USA


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Transducer selection table

LiNbO3

PZT-5A PVDF

Piezoelectric

d 33 (10-12 C/N) 6 400 .39~.44constant

g 33 (Vm/N) 0.023 0.025 -0.32

Mechanical Q factor 100 75 5~103 . .

Sound velocity (m/s) 7316 4500 2260

Acoustic impedance(10 6k m 2s

33 35 4

Work temperature( 0C)


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Application on human bodyeasur ng g ucose rom uman o y s qu e comp ex ue o w e

range of potentially interfering components. A number of factorsthat are to be considered for developing such a system :

a p ca s gna :Depth of penetration at least upto dermis layer of skin

Higher absorption by glucose compared to other constitutes of blood, water, protein, fat, melanin etc.Optical energy within the Maximum Permissible Engergy (MPE) asspecified in Safe use of lasers for health care facilities, - ANSI

Standard Z 136.3-2005 Pulse width and pulse repetition frequency meeting PA generationcondition.Test site (e.g. finger, earlobe etc.)

Optical signal delivery mechanism


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Phase-I : Glucose solutionarrie out PA measurement at 1 4 nm using

Nd:YAG laser with glucose solution of differentconcentrations

Result : Peak-to-peak value of the PA signal maintains a nearly linearrelationship with the concentration of glucose in the solution.

Conclusion : Can be considered for developing a non-invasive blood

glucose monitor


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Phase II: on human subject with OGTT

0.6

0.7

0.8

0.4

0.5

A s

i g n a

l ( m V )

Point of drinking

0.1

0.2

.

0 5 10 15 20 25 30 35 400Time (minute)

Variation of PA signal plotted with digitized signal captured through oscilloscope

Finding : Result closely matches the pattern of variation after consumptionof glucose by a subject with the result reported in the literature


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concentration

79

80

76

77

l i n m v

73

74 P A s

i g n

100 105 110 115 120 125 130 135 14070

71

Blood lucose level in m /dl

Blood glucose values measured with SMBG monitor ACCU CHEK Active


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Further work needed to realize the system

Although results achieved so far are quite encouraging, but needsfurther extensive testing and improvement in the design before it can

Modification of the front-end circuitryDesign of laser driver circuit

in FPGA Nullify the sources of error due to change in

Pressure

Temperature (both ambient and body)Melanin content of the skinOxygen saturation of bloodSubject dependent tissue condition at the test site (finger)

Any other physiological conditions

non invasive 20blood 20glucose 20 measuring 20system

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