Optical Sensor Shows Promise in Non-Invasive Continuous Glucose Monitoring


Optical glucose sensing techniques have been reported, but they require complex optical instrumentations found in laboratories, so feasibility for patient use has been challenging.

A new optical sensor has the potential to be used as a continuous glucose monitoring system, offering a non-invasive option for individuals with diabetes, according to results of a study published in Advanced Sensor Research. Currently, individuals with diabetes use either finger pricks or adhesive microneedles to measure glucose levels, which can be painful and cause itching, inflammation, and infections, according to a press release.1,2

Woman hands using lancet on finger at home to check blood sugar level | Image Credit: zakalinka - stock.adobe.com

Image Credit: zakalinka - stock.adobe.com

Non-invasive methods of glucose monitoring have been a target for nearly 30 years, according to the press release. Optical glucose sensing techniques have been researched, although they require complex optical instruments found in laboratories, making them impractical for patient use. Affordable and wearable glucose testing has been challenging, specifically when filtering out glucose signals from water absorption peaks. According to the press release, it has been nearly impossible for the tests to differentiate between water and glucose in blood.1

“Until now, there is no consensus on the unique spectroscopic signature of glucose, largely because the O-H bonds targeted in near-infrared spectroscopy for glucose detection are also abundant in water. This similarity makes it challenging to distinguish between glucose and water signals, especially in complex biological fluids and tissues,” Mingjie Yang, PhD, from the Royal Melbourne Institute of Technology (RMIT), said in the press release. “We optimized spectroscopy setup and analyzed transmittance to identify peaks unique to glucose. Our discovery finally provides the information necessary to move forward with miniaturized optical glucose sensing and we have developed a device prototype to suggest the foundation for futuristic non-invasive glucose sensor.”1

In the study, investigators identified 4 infrared peaks in glucose that could be used to differentiate glucose from water in aqueous and biological environments. The 4 peaks were 1605 nm, 1706 nm, 2145 nm, and 2275 nm, according to the study authors.2 The investigators constructed a miniaturized glucose sensor on a 1600 nm to 1700 nm waveband. The device connects to Bluetooth and uses a coin batter, allowing for continuous monitoring, according to the press release. Investigators found that the sensor detected glucose levels in the human body, ranging from 50 mg/dL to 400 mg/dL in blood plasma, which was comparable to the detection and sensitivity of larger laboratory-based sensors.1 The study authors reported that the device attained a limit of detection as low as 10 mg/dL.2

Key Takeaways

  1. Researchers discovered specific infrared peaks in glucose that can distinguish it from water, a major hurdle in non-invasive monitoring.
  2. This new sensor is lightweight, flexible, and uses Bluetooth for continuous monitoring.
  3. The sensor showed accurate blood sugar readings in a range comparable to existing lab-based sensors.

The prototype also used a surface-mounted device light emitting diode (SMD LED) and circuits of thin-film copper-coated polymide that were 110 microns thick, according to the press release. The device is also lightweight, which makes it more compact, and it is designed in a flexible patch-like fashion that offers a possibility of direct reading since the device can be worn directly on the skin.1

According to the press release, the device has been rigorously evaluated with aqueous glucose solutions and blood plasma, showing how the SMD LED will penetrate the skin. Further, the simulation suggested promising locations for the future investigation of the optical glucose sensor in clinical setting.1

RMIT University has filed a patent application on the optical glucose sensor technology, according to the press release.1

  1. Continuous non-invasive glucose sensing on the horizon with the development of a new optical sensor. News release. EurekAlert. March 19, 2024. Accessed April 2, 2024. https://www.eurekalert.org/news-releases/1038144
  2. Yang M, Dhanabalan SS, Robel MR, et al. Miniaturized Optical Glucose Sensor Using 1600-1700 nm Near-Infrared Light. Advanced Sensor Research. 2024. doi:https://doi.org/10.1002/adsr.202300160
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