Structured surface wetting of a PTFE flow-cell for terahertz spectroscopy of proteins

We have fabricated a terahertz compatible polytetrafluoroethylene (PTFE) based microfluidic flow-cell, in which terahertz time-domain spectroscopy of a range of concentrations of aqueous bovine serum albumin (BSA) was performed, demonstrating the device’s suitability for future studies of biomolecular interactions. The novel combination of oxygen plasma treatments and milling was used to both increase and decrease the wettability of the channel and surrounding substrate (to superhydrophobic levels) respectively, producing a stark contrast in contact angles allowing surface tension effects to confine liquid in the channel. PTFE is a chemically inert, bio-compatible material with ideal spectroscopic properties at sub-millimetre wavelengths. [Display omitted] •A PTFE based surface-tension confined flow-cell for terahertz spectroscopy was fabricated.•PTFE surfaces were modified to both increase and decrease wetting on the same substrate.•High wetting contrasts enabled water confinement due to surface-tension forces.•Terahertz time-domain spectroscopy was performed on a wide range of aqueous bovine serum albumin concentrations.•The confinement solution is robust, cost effective and rapid to prototype.