A chemical sensor microarray realized by laser printing of polymers

The fabrication of chemical sensor arrays using laser induced forward transfer (LIFT) as a means to deposit polymer layers to be used as chemically sensitive material is presented. LIFT is a direct, maskless technique offering high spatial resolution printing of a wide range of polymers and in this work it has been applied in the fabrication of a capacitive chemical sensor array with the ability to host up to 256 sensing sites. Each sensor in the array is composed of a Si membrane covered by a thin low temperature oxide layer and a polymer layer. Owing to the large number of sensing sites there is room for both sensitive polymer layer diversity as well as multiplicity, therefore expanding the capability for odour recognition. As a demonstration, a variety of polymers has been spotted on sensor arrays and tested during exposure to various concentrations of water, methanol and ethanol vapours. The deposited polymers showed good sensitivity depending on the analytes tested and the geometrical characteristics of the composite membranes.