Pulse actuation-readout scheme for bulk disk resonator based mass sensor

In the framework of developing an innovative label-free sensor for multyarrayed biodetecion applications, we demonstrate a novel technique for real-time tracking of the resonance frequency of a capacitive bulk disk resonator based mass sensor. The sensor is based on a polysilicon disk which shows a Q-factor of 3100 in air at 67.2 MHz, which is actuated electrostatically. The charged resonator is driven into resonance by a sinusoidal burst of only 200 cycles, and the free vibrating signal of the device is recorded with an oscilloscope. This scheme is much simpler, compared to a standard network analyzer scheme or the closed loop schemes, to extract the resonance frequency of the sensor, since only a function generator and an oscilloscope are used. The pulse setup allows us to achieve a temporal resolution of 0.01 seconds with a frequency noise floor of 1 kHz. Finally, a drop of glycerol was placed on the resonator surface and the evaporation has been monitored, demonstrating a mass resolution of 256 fg.