Authors: A. Heidari, YJ. Yoon, WT. Park, J.T.M. Lin
Affilation: Nanyang Technological University, Singapore
Pages: 365 - 368
Keywords: bulk acoustic resonator, biomass sensor, mass sensitivity, capacitive transducer
In recent years the use of micro and nano electromechanical (MEMS/NEMS) resonators for mass sensing applications has been extensively explored. In many applications, high sensitivity biomass sensors are required to sense small biological entities (e.g. low concentrated solution). Further miniaturization using nanofabrication techniques allows higher mass sensitivity, but it includes the low device-to-device performance reproducibility and difficulties to electrically interface. Quartz Crystal Microbalances (QCMs) have been successfully employed as mass sensors, but they are only able to detect few nanogerams due to their limited mass sensitivity. In a liquid environment, the diaphragms and cantilevers’ out-of-plane vibration are strongly damped, resulting in substantially lower Q factors and, thus, mass resolution and detection limit. These issues have been solved by using the dielectric filled lamé mode bulk acoustic resonator. As this resonator vibrates in in-plane mode, it shears the surrounding media instead of compressing. So it improves the quality factor in air and liquid environments. In addition, compared to previously reported mass sensors, the presented sensor can detect smaller biological agents. The biomass sensor has the mass sensitivity of -400 Hz/ng at a frequency of 37.8 MHz, and quality factor of 10,000.