Microvalves for Natural-Gas Analysis With Poly Ether Ether Ketone Membranes

We present the use of poly ether ether ketone (PEEK) as a membrane material for a new type of gas microvalve, which is suitable for the harsh environments of natural gas. The design, fabrication, and experimental characterization of the PEEK-based microvalves are presented first, revealing leakage levels of less than 230 nL·min^-1 under nitrogen and helium. Then, the main mechanical properties of the PEEK membranes are derived from both static and dynamic measurements, leading to a Young´s modulus of 3.1 GPa and an inplane anisotropic stress field, with both tensile and compressive components in two perpendicular directions and whose magnitudes are + 33.9 MPa and -6.8 MPa, respectively. A blister test gave an adhesion energy estimated between 61 and 158 J·m^-2. Finally, temperature cycles have been conducted on the microvalve, showing a resistance of up to 300°C, together with an improved closing of the membrane.