Construction Methods for Hybrid Polycarbonate-Silicon Microfluidic Devices.

Hybrid microfluidic devices combining thermoplastics with rigid substrates, such as silicon and glass, enable advanced biological applications but are difficult to bond due to differences in thermal and mechanical properties. These challenges render conventional high-temperature and high-pressure methods unsuitable, motivating the need for alternative sealing strategies. Here, we present three relatively low-cost sealing strategies for polycarbonate-silicon microfluidic devices: solvent bonding with protective masking to preserve channel geometry; low-temperature thermal bonding layer using a 100 µm low-density polyethylene (LDPE) interlayer; and mechanical compression with an O-ring cord that serves as a gasket. Each approach requires tailored design and assembly steps to ensure leak-tight seals. These strategies require no specialized equipment or expensive infrastructure, making them well-suited for prototyping hybrid microfluidic devices in academic research laboratories and resource-limited environments. Solvent bonding produced the highest leak resistance (up to 692 mmHg) with a robust polycarbonate-polycarbonate interface, while gasket compression yielded the most reproducible, visually clean seals with minimal pressure drop (2 mmHg at 10 mL/min). In contrast, LDPE bonding showed channel intrusion, elevated pressure drop (196 mmHg), and instances of delamination.