Partial casting method on water surface and preparation of multi-channel saw chemical sensor

Surface acoustic wave (SAW) devices can be used as vapor phase chemical sensors. If we make use of SAW devices with high frequency properties and multi-channel structures, highly sensitive and multi gas sensors can be realized. However, it is generally difficult to deposit different gas sensitive films on the propagation paths of monolithic multi-channel SAW devices. This paper describes the new coating method by which several types of gas-sensitive molecular films can be coated on the paths. The method is called “partial casting method on water surface”. It makes use of the water surface segmented by a trapezoidal frame, and the molecular film spread in the frame is compressed by the vertical movement of the frame and deposited on the substrate placed on the frame top. Several bilayers of dialkyl polyion complex and dimyristoyl phosphatidyl ethanolamine were coated on 36°Y-X LiTaOs SAW delay line oscillators, and odor sensor characteristics were successfully measured. It was confirmed from the present experiments that the method can be applicable to fabrication of multi-channel SAW chemical sensors with various kinds of molecular films.