Quartz Crystal Resonators with Electrodes of Conductive Polymers

Quartz crystal resonators are widely used in today's communication devices and systems as the essential enabler of signal processing with ubiquitous applications. The devices with metal electrodes are working well until recent years when the size of resonators is shrunk to such a degree that the metal density and consequently the gravimetric effect which causes frequency shift is considered to be avoided. With this objective, we began testing of conductive polymers as new materials for electrodes. With the conductive polymer PEDOT/ PSS electrodes processed by a simple procedure, samples of quartz crystal resonator with polymer electrodes are made. Through a standard testing procedure, it is found that basically the resonator samples are usable with distinctive parameters. For instance, with the same crystal blank, the resonator by polymer electrodes has a resistance about 20 times of the one with metal electrodes, and the quality factor is also about 20
^th
, as expected. Also the resonance frequency is higher due to less gravimetric effect. Clearly, the concept of polymer electrodes have been proven and future efforts will be on the improvement of the polymer materials and processing technique for acceptable properties and performances.