Friday, 12 June 2015

Noninvasive Photoacoustic Blood Glucose Measurement

Patent Filing No.: 670/KOL/2013

Award won:
1. 2nd Prize of USD 10,000 in Healthcare Innovation World Cup 2013 at New York, USA
2. DST-Lockheed Martin India Innovation Growth Program Award 2015

Diabetes is a highly prevalent disease with an estimated 387 million people suffering from it worldwide. Defects in insulin secretion and action prevent cells from taking up glucose from blood leading to hyperglycemia, i.e., high blood glucose levels, which results in a host of micro- and macro- vascular complications such as impaired vision and renal function. Large scale randomizedcontrolled
trials have shown that tight glycemic control with multiple glucose measurements and intensive insulin therapy leads to delayed onset and progression of complications, making it an important element of diabetes care. A continuous, non-invasive blood glucose monitoring system based on photoacoustic spectroscopy is proposed for diabetes care.

Brief description:
Present state-of-the-art glucose monitors require patients to lance their fingers and test drops of blood using electrochemical testing strips multiple times each day. The pain and discomfort associated with the procedure often leads to non-compliance and irregular testing, resulting in poorer treatment outcomes. The repetitive costs associated with the one-time use testing strips also prevent wide scale use in developing nations where healthcare costs could take up a major portion of household income. In addition, current methods are labour intensive and time consuming to implement frequently and yield discontinuous measurements. Non-invasive glucose monitoring based on photoacoustic spectroscopy offers painless measurement in a continuous manner allowing for better treatment outcomes. Continuous measurements would also allow for easier detection of hyper- and hypo- glycemic events, which might otherwise be missed when only two or three glucose measurements are made each day. This ultimately reduces the risk of complications associated with diabetes, leading to efficient diabetes management and lower healthcare costs.

Technical details:
The photoacoustic effect involves excitation of a sample by short duration intense pulses of electromagnetic radiation, such as a laser, leading to optical absorption followed by non-radiative heat release and thermoelastic expansion. In absence of excitation, this leads to the generation of a pressure wave in the sample. The generated pressure is proportional to the sample optical properties and is used to predict the sample constituent concentration. Blood glucose concentration is measured by selecting excitation wavelengths that are primarily absorbed by glucose molecules present in the
tissue. Glucose also affects the physical properties of the sample leading to changes in the sample photoacoustic response.

The measurement system consists of a pulsed laser diode which provides electromagnetic excitation, a piezoelectric transducer for measuring the generated pressure wave, and associated signal processing units. The photoacoustic signal obtained at the transducer output is amplified and processed to remove noise. The noise free signal is processed further and calibrated to obtain a glucose value. Trends in glucose concentration can be used by the diabetic to manage daily medication, nutrition, and exercise, and can be sent to a doctor periodically for follow up investigations. The signal processing, storage, and calibration can be done on a smart phone and the results can be continually updated to a central server for use.

The technique was initially validated in vitro on glucose solutions. Simulations performed to check variation in the photoacoustic response with glucose concentration were found to correlate with the experimental findings. The photoacoustic signal amplitude is observed to increase with the concentration of the glucose. Following this, in vivo measurements were made on tissue wherein the variation in photoacoustic responses to follow the glucose concentration trends.

Research Team: 
Mr. Praful P. Pai   Mr. Pralay Mandal   Mr. Shib Shankar Das   Mr. Omkar C. Kulkarni   Mr. Pradyut Kr. Sanki   Mr. Satyabrata Sarangi   Prof. Anindya  Sundar Dhar   Prof. Swapna Banerjee

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