This paper describes a microwave resonator incorporating microfluidic lab-on-chip sensor system capable of performing simultaneous differential measurement based sensing of liquid samples. The resonators are split-ring resonator shapes made of gold on glass substrates. Directly bonded on glass substrates are polydimethylsiloxane microchannels. Sensor system design incorporates a pair of identical resonators, one of which performs reference reading from the background. Tracking the difference of the responses of both resonators simultaneously, rather than a single one, is used to obtain a more linear and noise-free reading. The sensor system was produced with conventional fabrication techniques. It is compatible with low-cost, simple, easy to handle sensing applications. Results indicate that reliable differential measurement was possible owing to a well-matched pair of sensors with a response error as low as 0.1%. It was also demonstrated that differential measurement capability enables sensing with improved linearity. Measurements were performed with glucose solutions in the range of 3.2-16.1 mM, achieving a sensitivity of 0.16 MHz/mM.
Microwave resonator-based sensors offer low-cost, contactless, label-free sensing solutions in a variety of applications. Sensing is done by the observation of the shifts in resonant frequency of the sensor structure, which depends on resonator geometry, material and physical properties of the environment. It is observed that the readings can be significantly affected by changes in secondary physical parameters or sample localization on resonator. A double microwave resonator sensing system incorporating microchannels on glass substrates are proposed to address these challenges. PDMS microchannels bonded on glass substrates are mounted on split ring resonators fabricated via low-cost processes. Experiments are performed with glucose solutions of 1.4 mg/mL–3.0 mg/mL concentration range. Results confirm that the use of double resonators increase rejection of background noise, whereas microchannel use increases measurement stability. Overall measurement sensitivity is shown to be 0.92 MHz/(mg/mL). Further improvements are aimed with the bonding of microchannels directly on resonators fabricated on glass substrates.
Dielectrophoresis-based separation of microparticles and living cells are studied with computational and experimental methods. The flow behaviours of particles are modelled and simulated using COMSOL Multiphysics 4.3a software (COMSOL Ltd). Lab-on-a-chip devices having a titanium (Ti) interdigitated electrode layer on a glass substrate and a PDMS microchannel are fabricated to investigate the most effective design for separating particles based on their sizes. Polystyrene particles in different diameters (3.2 and 9.8 µm) are used in the experiments. Green polystyrene particles from red ones are fully separated in a current design. Enrichment of Jurkat cells having 10.1 average diameter in phosphate buffer solution (PBS) medium is achieved.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.