A micromachined interface for airborne sample-to-liquid transfer and its application in a biosensor system

Area of Science:

• Microfluidics and Sensor Technology
• Analytical Chemistry
• Materials Science

Background:

• Existing methods for detecting airborne trace amounts of narcotics and explosives are often slow and require bulky equipment.
• There is a need for a more efficient and portable interface for sample collection and pre-concentration in trace detection systems.

Purpose of the Study:

• To design and fabricate a novel micromachined interface for airborne sample-to-liquid adsorption and droplet transfer.
• To develop and test a new system for the fast detection of dust- and vapor-based narcotics and explosives traces.
• To demonstrate the gravitational invariance and reduced operational footprint of the developed interface.

Main Methods:

• Fabrication of a micromachined interface featuring a robust sheet liquid flow for sample adsorption.
• Characterization of the interface's flow and pressure properties.
• Coupling the microfluidic interface with quartz crystal microbalance (QCM) sensors for trace detection.
• Testing the system with known quantities of cocaine and heroine samples.

Main Results:

• Successful transfer and adsorption of various airborne samples using the micromachined interface.
• Detection of 50 ng cocaine samples with a 15 Hz frequency shift and 100 ng heroine samples with a 50 Hz shift.
• Demonstrated gravitational invariance of the open liquid interface, allowing operation in any orientation.
• Reduced detection time by 50% compared to previous systems, alongside reductions in machine size, weight, and cost.

Conclusions:

• The novel micromachined interface provides an effective platform for airborne sample adsorption and transfer.
• The coupled microfluidic-QCM system offers a fast, sensitive, and portable solution for detecting narcotics and explosives.
• The system's design improvements significantly enhance its practicality for real-world security applications.