Electroacoustic device having a transducer including a piezoelectric substrate, first and second electrodes of inverse polarity having respective first and second tracks provided on said substrate, the first and second tracks spiraling around a same center (C), the transducer being configured for generating a swirling ultrasonic surface wave in the substrate.

In an elastic wave device that utilizes longitudinal wave leaky elastic wave, an IDT electrode is provided on a first or second principal surface of a piezoelectric layer, an energy confinement layer that is laminated on the second principal surface of the piezoelectric layer so as to support the piezoelectric layer and confines energy of the longitudinal wave leaky elastic wave into the piezoelectric layer is provided, a thickness of the piezoelectric layer is or less when represents a wavelength determined according to an electrode finger pitch of the IDT electrode, and a groove is provided in at least one of the first and second principal surfaces of the piezoelectric layer, and the IDT electrode includes a portion in the groove.

An cartridge is combined with a smart device which is capable of communicating with a network to perform a portable, fast, field assay of a small sample biological analyte. A closed microfluidic circuit for mixes the analyte with a buffer with functionalized magnetic beads capable of being specifically combined with the analyte. A detector communicates with the microfluidic circuit in which the mixed analyte, buffer and combined functionalized magnetic beads are sensed. A microcontroller is coupled to detector for controlling the detector and for data processing an output assay signal from the detector. A user interface communicates with the microcontroller for providing user input and for providing user output through the smart device to the network.

Electroacoustic device having a transducer including a piezoelectric substrate, first and second electrodes of inverse polarity having respective first and second tracks provided on said substrate, the first and second tracks spiraling around a same center (C), the transducer being configured for generating a swirling ultrasonic surface wave in the substrate.

An electroacoustic transducer having an alternative finger structure is provided. The number of fingers of a cell of length A is divisible by four. The electrode fingers of the cell are divided into four groups. The distance (.sub.2) between the second group and the third group is less than the distance (.sub.1) between the first group and the second group and less than the distance (.sub.3) between the third group and the fourth group.