Coupled SAW Resonator Research Articles

Detecting Small Size Mass Loading Using Transversely Coupled SAW Resonator

In the detection of small size mass loading, such as a single cell, a micro droplet or an aerosol particle, the sensors with longitudinally coupled surface acoustic wave resonator (LC-SAWR) structure can hardly avoid waveform distortions. The relative size of mass loading to the sensitive surface of the detector is the main factor affecting the response of LC-SAWR. The smaller the relative size, the worse the waveform distortion. In order to avoid influences from the mass loading’s size, in this paper, a transversely coupled SAW resonator (TC-SAWR) was proposed in order to achieve high performance in sensing small size mass loadings. For the design and simulation of TC-SAWR, the two-dimensional coupling of model (2D-COM) theory and finite element method (FEM) were used in this work. In the experiment, SiO2 was deposited on the sensor’s surface as a small size mass loading. The results from simulation and experiment mutually demonstrated the advantage of TC-SAWR to conquer waveform distortion in the detection of small size mass loading.

An alternative method for suppressing undesired transverse modes in longitudinally coupled SAW resonator filters

As known, perturbing transverse modes arising from the waveguide properties of the interdigital transducers and reflectors can appear in SAW resonator filters. Usually, these undesired modes are suppressed by transducer apodization. This method has the disadvantage of increasing the transducer impedance. We propose a longitudinally coupled resonator filter, the basic elements of which are able to guide the two slowest waveguide modes alone, but to excite and receive the first mode only. The basic elements are arranged side by side forming the complete filter permitting coupling with each other weak enough to fulfill the filter specification. The suppression of undesired modes by the construction is demonstrated by transmission measurements.

Acoustically Coupled SAW Resonator Filters with Enhanced Out-Of-Band Rejection

Acoustically Coupled SAW Resonator Filters with Enhanced Out-Of-Band Rejection