Resonance Micro-Weighing of Sub-Picogram Mass with the Use of Adaptive Interferometer

Abstract

Mass of macroscopic object is easily measured by a suitable balance. However, this approach becomes inapplicable if mass of microscopic object is to be determined. Alternative approach for mass measurement is based on using the micromechanical resonator as an inertial balance where oscillation frequency is shifted by small quantities of adsorbed mass. In this work we present experimental results of applying an adaptive interferometry technique based on dynamic hologram recorded in photorefractive CdTe crystal for measuring picogram mass adsorbed on micromechanical resonators with dimensions 215×40×15 µm 3 . It is also shown that the resonance micro-weighing system based on adaptive interferometer has potential for reducing the threshold of mass detection down to 10 -17 g in the case of using a resonator with sub-micron dimensions.

Micro-Weighing Based Biosensor with Adaptive Interferometry

“…To excite vibrations, the cantilever was fixed on a piezoquartz plate and subjected to a sinusoidal electrical signal with an amplitude of up to 80 mV and varying frequency, supplied from an electrical signal generator. The vibrations of the cantilever were measured using a holographic adaptive interferometer [7,8], as shown in Figure 1. The interferometer object wave was reflected from the cantilever and propagated through a semi-insulating photorefractive CdTe:V crystal, where it was mixed with the reference wave.…”