Blood Glucose Level Monitoring Using an FMCW Millimeter-Wave Radar Sensor

Abstract

In this article, a novel sensing approach is presented for glucose level monitoring where a robust low-power millimeter(mm)-wave radar system is used to differentiate between blood samples of disparate glucose concentrations in the range 0.5 to 3.5 mg/mL. The proposed radar sensing mechanism shows greater capabilities for remote detection of blood glucose inside test tubes through detecting minute changes in their dielectric properties. In particular, the reflected mm-waves that represent unique signatures for the internal synthesis and composition of the tested blood samples, are collected from the multi-channels of the radar and analyzed using signal processing techniques to identify different glucose concentrations and correlate them to the reflected mm-wave readings. The mm-wave spectrum is chosen for glucose sensing in this study after a set of preliminary experiments that investigated the dielectric permittivity behavior of glucose-loaded solutions across different frequency bands. In this regard, a newly-developed commercial coaxial probe kit (DAK-TL) is used to characterize the electromagnetic properties of glucose-loaded samples in a broad range of frequencies from 300 MHz to 67 GHz using two different 50 Ω open-coaxial probes. This would help to determine the portion of the frequency spectrum that is more sensitive to slight variations in glucose concentrations as indicated by the amount of change in the dielectric constant and loss tangent parameters due to the different concentrations under test. The mm-wave frequency range 50 to 67 GHz has shown to be promising for acquiring both high sensitivity and sufficient penetration depth for the most interaction between the glucose molecules and electromagnetic waves. The processed results have indicated the reliability of using mm-wave radars in identifying changes in blood glucose levels while monitoring trends among those variations. Particularly, blood samples of higher glucose concentrations are correlated with reflected mm-wave signals of greater energy. The proposed system could likely be adapted in the future as a portable non-invasive continuous blood glucose level monitoring for daily use by diabetics.

Hypersensitized Metamaterials Based on a Corona-Shaped Resonator for Efficient Detection of Glucose

“…Glucose biosensors have been long used in biology, chemistry, food processing and diabetes diagnosis [1,2]. The developments of glucose biosensors, working on different principles, have been reported previously [3][4][5][6][7][8][9][10]. Among them, microwave-based biosensors have been widely used due to their high sensitivity, simultaneous measurement, fast response, robustness and low cost [11][12][13][14].…”

Low-cost portable microwave sensor for non-invasive monitoring of blood glucose level: novel design utilizing a four-cell CSRR hexagonal configuration

“…Preliminary tests were performed on a healthy male volunteer at age 29 before and after having the lunch meal while comparing the non-invasive measurements against a standard glucometer used as a reference for comparison. This testing recipe was guided by the fact that, in healthy non-diabetic people, the blood glucose level should measure between 72-99 mg/dL before a meal and should be less than 140 mg/dL two hours after a meal 32,33 . Therefore, a pre-prandial test was first performed for the tested subject by placing his fingertip suitably in the sensing region inside the fixture as shown in Fig.…”

“…Researchers have also been exploring sensing structures in the millimeter(mm)-wave band that enables shorter wavelengths and relatively acceptable penetration depth adequate to interrogate the glucose concentrations in body regions with thin tissues. For instance, in another work 32,33 we proposed a miniature sensing system that utilized a 60 GHz mm-wave radar for monitoring the blood glucose level. As a proof-of-concept the system was able to distinguish different synthetic blood samples of clinically diabetes-relevant concentrations in the range of 50-350 mg/dL by analyzing the backscattered signals from the sample-filled test tube placed at a distance from a compact radar sensor.…”

Errors in Broadband Permittivity Determination Due to Liquid Surface Distortions in Semi-Open Test Cell

“…The accurate value of liquid complex permittivity ε r = ε r − jε r is desired in many fields of science and technology [1] such as medicine, biology, chemistry, agriculture, radio communication, remote sensing [2][3][4], etc. The permittivity, according to [5,6], represents the interaction of a material with an electric field.…”