Complex permittivity characterization of serum with an air-bridge enhanced capacitor for quantifiable detection of glucose

Abstract

We proposed the complex permittivity characterization of serum sample on an air-bridge enhanced capacitor for the mediator-free glucose sensor in the radio frequency of 7.37 GHz. An air-bridge enhanced capacitor with integrated passive device process on a gallium arsenide substrate was implemented for the design, fabrication, and testing to enable effective quantifiable detection of glucose levels in human serum. The decomposition parameters such as complex permittivity, air-bridge capacitance, phase and correlation coefficient were extracted from the measured S-parameter. A high detectable resolution of 0.61 MHz/mg dl−1 and 3.4 pF/mg dl−1 for ten different subjects of serum in the concentration range of 65 to 245 mg/dl at a minimum glucose concentration of 65 mg/dl was realized. The findings support the development of resonance-based sensing by the characterization of complex permittivity with excellent linearity having a correlation coefficient of 0.9979, short assay time of 40 s, limit of quantization of 29.37 mg/dl, and minimum detectable glucose level of about 9.69 mg/dl.