Sounds similar to surface acaustic wave filters and delay lines, which were e.g. commonly used in televisions (to make the color signal of the preceding line ac

Sounds similar to surface acaustic wave filters and delay lines, which were e.g. commonly used in televisions (to make the color signal of the preceding line accessible while drawing the next line, it needs to be delayed by a line (64 µs). These work by turning the electrical signal into a mechanical strain wave travelling mostly on the surface of the substrate, where it can be filtered by mechanical means (think tuning forks, but etched into the surface) or simply delayed by the path length. The "receiving" end then turns the mechanical wave back into electricity.