A Non-Invasive Method of Monitoring Glucose in Blood Using a Planar Yagi-Uda Antenna and Microstrip Filter

This work presents a non-invasive method to determine the glucose levels in blood samples using a planar Yagi-Uda antenna and a novel microstrip filter. The proposed antenna operates at 5.5 GHz and exhibiting uni-directional pattern giving a maximum gain of 6.74 dBi at the operating band. A commercially available and low-cost FR-4 substrate of dimensions 30 mmx40 mmx1.6 mm is used as a dielectric substrate. A finger phantom resembling a human finger is designed in the simulation environment, which consists of bone, skin, blood, fat as different layers. The glucose concentration is varied from 0 mg/dL to 500 mg/dL and the shifts in the frequencies are observed by keeping the phantom at various locations surrounding the antenna. A good frequency shift of 26 MHz is observed when the phantom is placed below the antenna. A good similarity is observed between the simulation and measurement results. Also, a novel microstrip filter, operating at 5.5 GHz, is developed, and the frequency shifts are studied by keeping a finger phantom at the top of the filter. The designed filter is shown to give a maximum frequency shift of 4 MHz when the glucose concentration changes from 250 mg/dL to 500 mg/dL. This study is supported by analysing transmission coefficient parameters and group delay characteristics.