GlucoSense
Diabetes is one of the most common diseases in the modern age and is growing at a fast pace. My father, being a diabetic patient, has to endure the discomfort of pricking his fingers multiple times a week to draw blood for glucose measurements. The repeated pain, the constant need for supplies, and the lingering marks on his skin inspired me to seek a solution. Upon researching, I realized that millions of people around the world face the same daily struggle.
Current invasive methods are inconvenient, painful, and costly. For instance, a type-2 diabetic patient typically needs to test their glucose levels three to four times a day. With over 460 million people living with diabetes globally, the scale of the problem is immense. Unfortunately, non-invasive alternatives like mid-infrared (MIR), near-infrared (NIR) spectroscopy, and optical polarimetry have faced significant hurdles. While promising, these techniques struggle with accuracy due to light scattering, interference from other biomolecules, and the complexity of the necessary equipment. Although accurate, optical coherence tomography (OCT) is impractical for everyday use due to its high cost and bulky setup.
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To bring this technology to Indian markets, I founded GlucoSense and raised $20,000 from private healthcare firms. Find the grant letter here. Read my manuscript here.
Optical Polarimetry and Chiral Blood Glucose
Optical polarimetry leverages the chiral nature of glucose, a molecule that can rotate plane-polarized light due to its asymmetry. This property makes polarimetry an ideal candidate for non-invasive blood glucose monitoring. The specific angle of light rotation is directly proportional to the glucose concentration in the sample and can be calculated following the Beer-Lambert law. By measuring this angle, optical polarimetry offers a potential way to estimate glucose levels in the blood without drawing blood. However, traditional polarimetry faces challenges with signal noise, as light scattering in human tissues complicates accurate measurement​
Using Polarimetry and Anterior Chamber of the eye
Purvinis et al. conducted a study on noninvasive polarimetric-based glucose monitoring, specifically in the anterior chamber of the eye of rabbits. This study highlights the potential of optical polarimetry for physiological glucose measurement. Several studies show that the glucose concentration in the aqueous humor of the eye is closely related to that of the bloodstream. But, due to the bulky setup and the expensive materials used, this is not a viable consumer-friendly solution
Photonic Crystals and Depolarization Cancellation
Photonic crystals are periodic structures that can manipulate the propagation of light. By designing specific photonic bandgaps, these structures can allow or block certain wavelengths. In optical polarimetry for glucose sensing, photonic crystals offer an innovative way to manage and refine light, ensuring that only the desired light signals are transmitted through the tissue. This capability is particularly useful for filtering polarized light signals. In my research, I have developed a photonic crystal design that tackles light depolarization. When light passes through human skin, it scatters and interacts with other chiral molecules, generating noise in the polarized signal. My design uses 1D photonic crystals that selectively transmit polarized light while blocking depolarized signals. This reduces the noise-to-signal ratio and enhances the accuracy of glucose measurements.
Proposed Design
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My design consists of alternating layers of SiO2 and TiO2, forming a 1D photonic crystal that selectively allows either S-polarized or P-polarized light to pass through. By incorporating defect layers, I have optimized the structure to block depolarized light, which otherwise interferes with accurate glucose measurements. The angle and thickness of the layers have been meticulously engineered to create sharp bandgaps, ensuring precise transmission of light through the skin. This approach minimizes signal interference and allows for more accurate non-invasive glucose readings
