Detecting glucose through painless photoacoustics

 Using painless Photoacoustic to detect glucose in diabetes 

There are a number of obstacles and issues with diabetes detection that may compromise precision, effectiveness, and accessibility. Here are a few important issues:

1. A delayed diagnosis
Many people don't get a diagnosis until they have serious problems or symptoms.

Early identification is challenging since type 2 diabetes, in particular, develops gradually.

2. Absence of Early Stage Symptoms
Many people with early-stage diabetes or prediabetes don't show any symptoms at all.

Unless there are risk indicators, such as obesity or family history, routine screening is sometimes neglected.

3. Inaccurate or Untrustworthy Test Findings
FBS, or fasting blood sugar: Results can change based on illness, stress, and food.

People with anemia or other blood abnormalities may have erroneous results from the HbA1c test.

Because of the required fasting and waiting time, the oral glucose tolerance test (OGTT) may be inconvenient.

4. Inaccurate diagnosis
Particularly in adults, type 1 diabetes can occasionally be mistaken for type 2 diabetes.

If appropriate testing is not performed, gestational diabetes in pregnant women may go unnoticed.

5. Price and Availability
Continuous glucose monitoring (CGM) and other advanced diagnostics are costly and not commonly accessible.

Diabetes screening may be scarce in low-income communities, which could result in an underdiagnosis.

Non-Invasive Detection Methods' Reliability
Although there is continuous research on non-invasive glucose monitoring techniques (such as analyzing breath, perspiration, or tears), these approaches are not yet dependable enough for clinical application.

7. Variability by Ethnicity and Genetics
Although diabetes is more common in some ethnic groups, genetic variations in the course of diabetes may not be taken into consideration by conventional detection techniques.

8. Reliance on Self-Observation
Patients might not follow suggested testing schedules.

Results from home glucose monitoring devices can be deceptive if they contain errors.

Typically, invasive techniques that involve puncturing tiny needles into the skin are used to measure blood glucose. However, diabetics must check their blood sugar levels numerous times throughout the day. In addition to being annoying, this frequent needle use raises the possibility of infections.

Researchers from the Indian Institute of Science (IISc) Department of Instrumentation and Applied Physics (IAP) have developed a novel method termed photoacoustic sensing that provides an alternate answer.

This method involves shining a laser beam on biological tissue, which causes the tissue to absorb the light and warm up slightly (less than 1°C). Sensitive detectors can detect the vibrations produced by the tissue's expansion and contraction as ultrasonic sound waves. Individual "fingerprints" are created in the sound waves that are released by the tissue's various components and molecules absorbing varying amounts of incident light at various wavelengths. Crucially, the tissue sample under study is not harmed by this process.

The scientists used this method to quantify the concentration of a single molecule, glucose, in the current investigation. They employed polarized light, which is a type of light wave that only oscillates in one direction. For instance, sunglasses lessen glare by obstructing light waves that oscillate in specific directions.

As a chiral molecule, glucose has an intrinsic structural asymmetry that, when polarized light interacts with the molecule, rotates its oscillation orientation. Remarkably, the group discovered that altering the orientation of the polarized light interacting with the glucose in the solution altered the intensity of the sound waves that were released.

In reality, we have no idea why altering the polarization state affects the auditory signal. However, Jaya Prakash, an assistant professor in IAP and the corresponding author of the study that was published in Science Advances, adds, "We can establish a relationship between the glucose concentration and the intensity of the acoustic signal at a particular wavelength."

The intensity of the acoustic signal reflects the rotation of the polarized light caused by glucose, which increases with concentration. Thus, the researchers were able to estimate the glucose content by working backwards and assessing the acoustic signal's strength.

With almost clinical accuracy, the researchers were able to determine the amount of glucose present in animal tissue slices, water, and serum solutions. Additionally, they were able to precisely measure the amount of glucose present in the tissue at different depths.

"We can use the time series data to map our acoustic signals to the depth at which they are coming from if we know the speed of sound in this tissue," says Swathi Padmanabhan, the paper's first author and PhD candidate. The researchers were able to obtain precise measurements at different tissue thicknesses because sound waves don't disperse much inside tissue.

Additionally, the scientists employed the sensor setup to monitor a healthy participant's blood glucose levels before and after meals for three days as part of a pilot study.

It was really difficult to find the ideal setup for this experiment. Our current laser source is costly and large because it must produce extremely tiny nanosecond pulses. To use it in therapeutic settings, we must make it smaller. "My lab colleagues have already begun working on this," Padmanabhan says.

By altering the wavelength of the light, the authors think that this method could theoretically be applied to any chiral chemical. The concentration of naproxen, a medication frequently used to treat minor pain and inflammation, in an ethanol solution was also estimated during the investigation. Such a technology can have a wide range of uses in diagnostics and healthcare because many regularly used medications are chiral in nature.