Re-usable multi-inlet PDMS fluidic connector

A microfabricated re-usable multi-inlet fluidic connector chip in PDMS (polydimethylsiloxane) is introduced. A connector takes up ca. 1 mm2 area and inlet density is limited principally by capillary tubing dimensions. Anisotropically etched silicon mold, with patterns matching those of the microfluidic chip, and dummy fibers have been used in PDMS casting. The connector chip material is self-sealing PDMS, which eliminates the need for gluing. This feature enables tubing to be attached and removed repeatedly, as long as the PDMS surfaces in contact with the microfluidic chip remain clean. Both imide-coated glass capillaries and polymeric PEEK (polyetheretherketone) tubes have been successfully connected to a microfluidic nebulizer chip which has one liquid and two gas ports. The connections were measured to withstand overpressures up to 220 and 20 kPa with and without additional compression, respectively. The fact that the connector chip is fabricated independently of the microfluidic chip improves significantly assembly yield of the fluidic system, because the microfluidic chip is not subject to gluing or other assembly operations. We tested the PDMS chip successfully with the nebulizer chip in mass spectrometry application. Even though room temperature performance of the connector chip was excellent, at elevated temperatures (above 50 °C) significant background signal originating from PDMS can be seen in mass spectra. This limits the usability of PDMS parts in sensitive mass spectrometry applications.