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A guiding light: spectroscopy on digital microfluidic devices using in-plane optical fibre waveguides
Kihwan Choi1,2,3, Jared M Mudrik1, Aaron R Wheeler4,5,6
1Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
Analytical and Bioanalytical Chemistry
|August 3, 2015
Summary
We developed a new in-plane spectroscopy method for digital microfluidic devices. This technique significantly enhances absorbance sensitivity for microvolume samples, outperforming existing methods.
Area of Science:
- Analytical Chemistry
- Spectroscopy
- Microfluidics
Background:
- Digital microfluidic (DMF) devices enable precise manipulation of micro-volumes.
- Traditional optical measurements on DMF devices are limited by droplet geometry.
- Enhanced sensitivity is crucial for analyzing dilute samples.
Purpose of the Study:
- To introduce a novel in-plane spectroscopy method for DMF devices.
- To improve the sensitivity and calibration of optical measurements on DMF devices.
- To enable on-demand adjustment of absorbance path length for variable sample analysis.
Main Methods:
- A custom manifold was designed to align optical fibers in-plane with a DMF device.
- In-plane optical measurements were performed on droplets within the DMF device.
- Droplet stretching and adjustable fiber-to-fiber gap width were utilized to modify absorbance path length.
Main Results:
- The in-plane method achieved approximately 14x greater sensitivity than vertical absorbance measurements.
- Calibration sensitivity for thymol blue surpassed the NanoDrop system by approximately 2.5x.
- Liquid lensing effects increased light transmission by approximately 2x, enhancing measurements.
Conclusions:
- The novel in-plane digital microfluidic spectroscopy system offers superior absorbance sensitivity.
- The system allows for tunable absorbance path length, ideal for interrogating dilute samples.
- This method holds promise for diverse analytical applications utilizing microfluidic devices.
