CYTOP-assisted vacuum storage enhancement of PDMS microfluidic chip for passive-driven fluid injection

Herein, we present a straightforward method for spin-coating CYTOP onto PDMS. This approach provides a pumpless microfluidic chip that exhibits enhanced vacuum storage efficiency and fluid transport performance compared to PDMS-only chips. The short retention time of vacuum-driven microfluidic systems is mitigated by sealing the porous structure of the PDMS-CYTOP complex, a transparent fluoropolymer with low-gas permeability and high-chemical stability. Spin-coating at 5000 revolutions per minute (rpm) resulted in superior uniformity and reduced roughness that effectively minimized vacuum storage losses compared with those at other speeds. The optimized coating maintained vacuum retention efficiencies greater than 95% after 30 min and demonstrated stable fluid transport, comparable to its initial state, even after unpackaging. This simple and accessible fabrication method eliminates the need for specialized equipment. The CYTOP-coated chip holds significant potential for applications in biosensors, organ-on-a-chip systems, and cell loading, particularly for portable and energy-efficient microfluidic technologies.