Leakage-Free Bonding of a Serpentine PDMS Microfluidics Directly on a Screen-Printed Electrode

Electrochemical sensors and biosensors have been focused on the development of a microfluidic integrated on a screen-printed electrode (SPE) for use in medical diagnosis. Polydimethylsiloxane (PDMS), an elastomer material, has been widely used for the fabrication of microfluidic devices. Regarding PDMS-based microfluidic integrated on SPE, there is a significant issue of leakage, especially for a continuous monitoring system. In this study, we aim to investigate the effect of PDMS ratio on PDMS-based microfluidic with serpentine pattern integrated commercial SPEs to overcome the leakage problem when using in a continuous flow system. The mechanical properties of different PDMS ratios, including 10:1, 10:0.8, 10:0.6, 10:4, and 10:0.2 were examined in terms of elastic modulus using an Instron universal testing machine. Additionally, leakage test was performed by continuous flow through microfluidic devices prepared in different PDMS ratios and integrated directly onto a commercial SPE. The results revealed that leaks occurred easily when using the microfluidic device fabricated with the standard PDMS mixing ratio at 10:1, whereas the more flexible PDMS microfluidic device at a ratio of 10:0.6 provides a suitable ratio with an excellent performance of leakage-free. This indicates that a stiff PDMS-based microfluidic device can cause leakage more easily than a flexible PDMS-based microfluidic device. Hence, the PDMS ratio of 10:0.6 exhibits a great promise in fabricating a microfluidic integrated on commercial SPE toward the development of microfluidic-based electrochemical sensors and biosensors for use in a continuous monitoring system.