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The gas sensing properties of functional metal oxide layers depend on multitude parameters, including vacancy concentration, layer morphology and thickness, size and shape of the nano/microstructure, and porosity. Using colloidal tin oxide inks we demonstrate a layer by layer deposition technique to control the thickness and composition of gas sensitive layers. To do this we combine inkjet-printing with colloidal suspensions of SnO2 particles to provide a scalable method to interface microelectromechanical systems (MEMS) with nano particles. The approach may pave the way towards an industry ready integration technique to incorporate gas sensitive quantum dots or hybrid nanomaterials in arbitrary sensing devices.

Abstract: “Nano-Macro” and “Nano-Micro” integrated sensor-devices have been fabricated via sol–gel dip-coating the nanocrystalline indium oxide -doped tin oxide thin films on the Pyrex glass and the microelectromechanical system (MEMS) substrates. The electrode-spacing for the “Nano-Macro” integrated sensor-device is maintained at 1cm while that for the “Nano-Micro” integrated sensor-device is reduced to 10 and . These sensor-devices with different electrode-spacing are characterized using glancing-angle X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), and high-resolution transmission electron microscope (HRTEM); and subsequently utilized for sensing 900ppm hydrogen at room temperature under the dynamic test-condition. The “Nano-Macro” and “Nano-Micro” integrated sensor-devices exhibit maximum room temperature sensitivity of and with the response time of 3h and 250–350s (for the room temperature sensitivity of ), respectively. Moreover, the “Nano-Micro” integrated sensor-device with the smaller electrode-spacing shows better response kinetics relative to that of the sensor-device with the larger electrode-spacing . The observed sensor-behavior has been explained based on the effect of electrode-spacing on the kinetics of the sensing mechanism. [Copyright &y& Elsevier]