Surface acoustic wave (SAW) sensors are a promising class of microelectromechanical devices that leverage changes in the transmission of an acoustic wave across a sensing surface to detect physical phenomena. These devices can be small, versatile, and are extremely sensitive to even low-intensity events like a liquid drop. It may open whole new types of sensing opportunities in biomaterial monitoring and interaction. Unfortunately, despite the widespread adoption of mass-produced SAW devices by the industry, the cost and difficulty of fabricating custom SAW devices for research and prototyping have remained high.

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We introduce a low-cost, simpler, and accessible method for fabricating custom SAW sensors. This method relies on commercially only available commercial printed circuit boards (PCBs) as the primary fabrication process and does not require cleanroom conditions, nor specialized equipment. This makes the fabrication of these devices much simpler and more accessible. The devices are then characterized for material interaction and classification. Finally, we show two feasible sensing applications that detect hard (such as solids and granules) and soft food types (such as liquids, and slurries). Our aim is to empower the research community to develop custom SAW devices more easily to explore novel sensing scenarios that will ultimately unlock new interactive applications.