Post Arrays for the Immobilization of Vapochromic Coordination Polymers for Chemical Sensors

This paper presents a new immobilization method for Vapochromic Coordination Polymers (VCPs) for micromachined fluorescence chemical sensors. The method involves creating a sheet of post arrays in polydimethylsiloxane (PDMS) to trap and adhere the VCPs to the sensing surface. The method is simple, robust, and employs inexpensive micro-molding of PDMS polymer. Results suggest that, compared to un-patterned (flat) PDMS surfaces: 1) the VCPs on the patterned surfaces can detect ammonia gas without rendering the VCP inert (unable to fluoresce) or inaccessible; and 2) the technique has improved immobilization (attachment of VCP). We show that as the shapes of the top of the post arrays are changed from simple to mushroom-shaped caps, the sensitivity of the sensing surface is increased. Ammonia detection in the range of 5 ppm is possible with the most pronounced mushroom-shaped posts.