Diamagnetically levitating resonant weighing scale

TL;DR

This paper demonstrates a high-precision, zero-power diamagnetic levitating resonant weighing scale using a graphite plate, capable of microgram-level mass measurements for biological and chemical applications.

Contribution

It introduces a novel diamagnetically levitating resonant sensor with calibration and real-time measurement capabilities, achieving nanogram resolution.

Findings

Mass resolution down to 4.0 ng achieved.

Sensor effectively measures evaporation rates of nano-litre droplets.

Stable, zero-power levitation enables sensitive mass detection.

Abstract

Diamagnetic levitation offers stable confinement of an object from its environment at zero power, and thus is a promising technique for developing next generation unclamped resonant sensors. In this work, we realize a resonant weighing scale using a graphite plate that is diamagnetically levitating over a checkerboard arrangement of permanent magnets. We characterize the bending vibrations of the levitating object using laser Doppler vibrometry and use microgram glass beads to calibrate the responsivity of the sensor's resonance frequency to mass changes. The sensor is used for real-time measurement of the evaporation rate of nano-litre droplets with high-accuracy. By analyzing the resonator's frequency stability, we show that the millimeter graphite sensor can reach mass resolutions down to 4.0ng, relevant to biological and chemical sensing concepts.