Reliable, Fast and Reusable Interfacing of High-Frequency Signals to Disposable Lab-on-a-Chip Devices

Abstract

This work presents a novel manner of interconnecting high-frequency signals from laboratory instruments to a disposable lab-on-a-chip chip with an interconnect box (ICB). The ICB can connect with a standard coaxial connector to microwave lab equipment and uses a spring levered interface with elastomer conductive pins to connect to the disposable chip. With the spring-system, a new microwave-microfluidic chip can be mounted reliably on the setup in a couple of seconds. The high-frequency interface within the ICB is protected from the environment by an enclosure having a single slit for mounting the chip. The gold-on-quartz technology and casting of polydimethylsiloxane was used to develop an interdigital capacitor (IDC) for microwave sensing and heating for continuous flow microfluidics. Different isopropyl alcohol-water mixtures were flushed through the channel over the IDC and sensed based on the measured reflection coefficient measurements of the interconnected IDC on quartz. Using calibration techniques, the dielectric properties were extracted and good agreement with values in literature was obtained. At last, a deionized water sample of $2\mu \mathbf{L}$ was heated with heating rates of 50° C/s.