Dry-Mass Sensing for Microfluidics

TL;DR

This paper introduces a novel microfluidic-based dry mass sensing method using a quartz crystal microbalance with an on-chip spray nozzle, enabling real-time, accurate analyte quantification without liquid damping effects.

Contribution

It presents a new dry mass sensing technique that interfaces microfluidics with an electromechanical sensor, overcoming limitations of liquid-based measurements.

Findings

Sensitive detection of nanogram salt and protein deposits.

Real-time dry mass measurement in microchannels.

No loss of sensor quality factor in dry detection mode.

Abstract

We present an approach for interfacing an electromechanical sensor with a microfluidic device for the accurate quantification of the dry mass of analytes within microchannels. We show that depositing solutes onto the active surface of a quartz crystal microbalance by means of an on-chip microfluidic spray nozzle and subsequent solvent removal provides the basis for the real-time determination of dry solute mass. Moreover, this detection scheme does not suffer from the decrease in the sensor quality factor and the viscous drag present if the measurement is performed in a liquid environment, yet allows solutions to be analysed. We demonstrate the sensitivity and reliability of our approach by controlled deposition of nanogram levels of salt and protein from a micrometer-sized channel.