Multiparameter Microwave Characterization and Probing of Ultralow Glucose Concentration Using a Microfabricated Biochip

Abstract

This paper presents a planar biochip consisting of electromagnetically coupled, symmetric, square open loops for the multiparameter microwave characterization of deionized water, a phosphate-buffered saline solution, and a fructose-deionized water solution. The characterization additionally includes the probing of an ultralow glucose concentration in a very small volume of human sera and in solutions of D-glucose powder and deionized water. The interaction between the coupled electromagnetic field and the aqueous solution sample translates into a predictable relationship between the electrical characteristics of the biochip (magnitude and phase of S-parameters, attenuation, phase constant, group delay, characteristic impedance, and effective complex permittivity) and the physical properties of the solution. Owing to the microfabrication technology used for fabricating the proposed microbiochip, it is possible to develop robust, compact square open loops with a microsized coupling gap that characterizes a very small volume (1 µL) of the sample. Additionally, the biochip's impedance peaks at its resonances were modeled using glucose-level-dependent coupling capacitance between folded square open loops and mutual inductance between center-loaded T-shaped stubs. These peaks linearly shifted in frequencies and markedly varied in impedance. Consequently, a physiologically relevant amount of glucose (50-400 mg/dL) with a high sensitivity (up to 2.036 Ω/(mg¨dL´1)) and an ultralow detection limit (up to 4.8 nmol/L) was linearly detected.

Design of an ELC resonator-based reusable RF microfluidic sensor for blood glucose estimation

“…Earlier works have used Petri dishes, cuvettes and large containers for holding the sample but the necessity of having large quantities of blood and oversized sample holder limits their practical applicability 31 – 33 . Sample droplets may also be directly placed on to the sensor’s sensing region for clinical diagnostic applications 34 , 35 . Of late, microfluidic channels are extensively used for conveying the test sample to the sensing unit 36 , 37 .…”

Real-time accurate quantification of nanoliter ethanol using performance-optimized micro-fabricated microwave resonant sensor

“…So far, optical spectroscopy [5], mass-sensitive detection [6], and ultrasonic techniques [7] are among the most commonly investigated ethanol sensing methods; however, these conventional analytical methods are time-consuming, complex, and subject to high-overheads. With the advancement of micro-fabrication techniques, microwave resonant micro-sensors have, alternatively, showed simple, rapid, label-free, reusable, and high-sensitivity characterization of the ultra-low level of biomolecules in aqueous solutions [8]. In addition, features such as multidimensional detection capability and lab-on-achip compatibility have established these microwave sensors as competitive candidates for an increasing number of biosensing applications [9,10].…”

Polyimide-derived laser-induced porous graphene-incorporated microwave resonator for high-performance humidity sensing

“…17) However, difficulty with transferring the graphene without breaking the induced carbon chains onto sensors hinders its applications in sensing technology. 18,19) Features such as potential high sensitivity and real-time detection capability 20,21) have rendered a microwave resonant platform a favorable candidate for various sensing applications including humidity sensors. 22,23) Many attempts [24][25][26][27] have been made aimed at enhancing the sensitivity and speeding response time of microwave humidity sensors.…”