Non-Invasive Blood Glucose Measuring System

PRESENTED BY:

MD. NAJMI ALAM

1MJ07TE027

TELECOMMUNICATION

MVJ COLLEGE OF ENGINEERING

Under the guidance of:Mrs. Navya Vipin

Asst Prof., Dept. of TEMVJCE

Head of the DepartmentMrs. Savitha H.K

Asst Prof., Dept. of TE MVJCE

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

Management of diabetes

Diabetes related long term complications are leadingcause of death

The complications can be reduced by 50-75% by tighterglycemic control

Frequent monitoring Adjusting the medical nutritional therapy, exerciseand medications to prevent hyper- or hypoglycemia

(Source : The Diabetes Control and Complications Trial Research Group, ‘The effect of intensive treatment ofdiabetes on the development and progression of long terms complications in insulin-dependent diabetes mellitus’,

N. Engl. J. Med. 329(14), 977-986 (1993))

Present technique of monitoring blood glucose

Either invasive or minimally invasive

Being off-line methods-Time consumingLabour intensive

May not reflect real-time status of the glucosecan cause cell contamination

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

Why non-invasive method ?

Will remove all shortcomings of present techniques

Improve quality of life

Reduce complications and mortality associated withthe disease

Possibility of developing artificial pancreas

Potential non-invasive optical methods

Infrared and Near-infrared absorption spectroscopy

Near-infrared scattering technique

Polarimetry technique

Raman spectroscopy

Photoacoustic spectroscpy

Photoacoustic MethodModulated laser beam

Excited state

Pressure wave

Acoustic transducer

AbsorptionAbsorption

of light

Sample

Radiative

transitionNon-radiative

transition

Ground state

Ah A

A Aheat

Factors affecting PA generation

Optical absorption coeff.

RadiativeRelaxation

Flourescence,Phosphorescence

Nanosecond PulsedLaser Beam

Wavelength

Pulse Width, PRFSkin and Tissue

Local Absorptionglucose molecules

Local Temperature E i a d

Ei : Incident optical energyμa : Absorption coefficient

d : Length of the cylinder within the sampleoccupied by the optical beam

Cp : Specific heat capacity for a constant pressureρ: Density of the medium

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

β : Volumetric thermal expansion coefficient ofIncrease T

Specific heat capacity C p VVol. expansion coeff.

AdiabaticExpansion V TV

Pressure Wave

the medium

T : Rise in temperature

B : Bulk modulus

v : Speed of sound in the medium

2

Speed of sound

v B/

EiadGeneration p B t B

CpVTransducer type &

Pressure DetectionTransducer Dimension

v

Cp

Eia 2 r

Dependence of PA signal on glucose

concentration

Δp

2βv

Cp

Eμi a2

πr

Offers higher detection sensitivity with simple apparatus

More immune to scattering

Phases of development

The total development process has been planned intwo phases

Phase I

Validation of the technique with glucose solution

Phase IIApplication on human subject

Block diagram of the proposed non-invasive blood glucose monitoring system

Pulse Driver

Generator Circuit

Laser

Diode

Piezoelectric

Transducer

Low Noise

Amplifier

DIGITAL SIGNAL PROCESSING BLOCKS

Analog toSignal Fast FourierDigital Peak

DigitalAverager Transform DetectorConverter

Calibration

Disply

Correction

Factors

System Photograph

Choice of components

Acoustic signal detector Sensitive

Rugged Insensitive to changes in ambient conditions

Choice of wavelength

905 nm

905nm

905 nm wavelength gives desired depth of penetration and absorption byWater and other constitutes of blood are less compared to glucose.

Absorption profile of glucose

CGG

M 1

Comparison between 905 nm and 1064 nm

Parameter 905 nm 1064 nm

Absorption in tissue Slightly higher than Lower than atat 1064nm 905nm

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

Absorption in glucose Low Very high

Sensitivity to oxy-hemoglobin Less Highand deoxy-hemoglobin

Power output of laser diode 90 watt 2 watt

Optical source and acoustic detector

Optical sourcePulsed Laser diode having λ = 905 nm

Model - PGAS1S12 from EG&G OptoelectronicsPulse width : ~100 ns

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

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

Transducer selection table

LiNbO3 PZT-5A PVDF

Piezoelectricd33 (10-12 C/N) 6 400 .39~.44constant

g33 (Vm/N) 0.023 0.025 -0.32

Mechanical Q factor 100 75 5~10

Density(g/cm3) 4.64 7650 1.78

Sound velocity (m/s) 7316 4500 2260

Acoustic impedance(106 33 35 4kg/m2s)

Work temperature(0C) <1100 <360 <60

Advantages Wide band, Inexpensive, Wide band,rugged High Inexpensive

sensitivity

Disadvantages Expensive Ringing Non-rugged

Application on human bodyMeasuring glucose from human body is quite complex due to wide

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

a) Optical signal : Depth of penetration at least upto dermis layer of skin

Higher absorption by glucose compared to other constitutes ofblood, water, protein, fat, melanin etc.

Optical energy within the Maximum Permissible Engergy (MPE) asspecified in ‘Safe use of lasers for health care facilities, - ANSIStandard Z 136.3-2005’

Pulse width and pulse repetition frequency meeting PA generationcondition.

Test site (e.g. finger, earlobe etc.) Optical signal delivery mechanism

Phase-I : Glucose solution

Carried out PA measurement at 1064 nm usingNd: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 bloodglucose monitor

Phase II: on human subject with OGTT

0.8

0.7

0.6

0.5

0.4

0.3 Point of drinking

0.2

0.1

00 5 10 15 20 25 30 35 40

Time (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

Variation of PA amplitude with glucoseconcentration

80

79

78

77

76

75

74

73

72

71

70100 105 110 115 120 125 130 135 140Blood glucose level in mg/dl

Blood glucose values measured with SMBG monitor ACCU CHEK Active

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 canbe considered for clinical use.

Modification of the front-end circuitry Design of laser driver circuit

Development of Signal Processing Algorithms and implementationin FPGA

Nullify the sources of error due to change in Pressure

Temperature (both ambient and body) Melanin content of the skin

Oxygen saturation of blood Subject dependent tissue condition at the test site (finger) Any other physiological conditions

BIBLIOGRAPHY

1. Amos AF, McCarty DJ & Zimmett P (1997) The rising global burden of diabetes and its complications: estimates and projections to the year 2010. Diabetic Medicine, Supplement 5: S1-S5.

2. Lahmann W, Ludewig HJ, & Welling H (1977) Opto acoustic trace analysis in liquids with the frequency modulated beam of an Argon ion laser. Analytical Chemistry 49: 549-551.

3. Oda S, Sawada T & Kamada H (1978) Determination of ultra trace Cadmium by laser-induced photoacoustic absorption spectroscopy. Analytical Chemistry 50: 865 867.

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