Abstract
This work reports on optoelectronic-based heaters that can transduce low-power optical images into high-power heating to melt frozen liquids and form desired microfluidic circuitry. The mechanism of optoelectronic heating (OEH) was studied and characterized. OEH relies on photocurrent heating in the illuminated parts of actuating images. Resolution was affected by dark current heating. Photocurrents and dark currents were measured and related to the operating parameters. Successful melting of a frozen media within seconds with 2 mW light patterns and a 4 V operating voltage was demonstrated with feature sizes down to 200 μm × 200 μm. Strategies to increase resolution were addressed. It was shown that the size and location of heating areas can be reliably and rapidly reconfigured by changing the actuating image.
Highlights
Microelectromechanical system (MEMS) techniques have enabled thermal control at the microscale and thereby opened up the way to new applications
An optoelectronic-based heater is reported for the first time. It enables heating confined at microscales with low-power light pattern actuation
Dark currents can be mitigated by improving the photoconductor quality and by minimizing background illumination
Summary
Microelectromechanical system (MEMS) techniques have enabled thermal control at the microscale and thereby opened up the way to new applications. Microheating has been applied to various chemical and biological processes [1, 2], where accurate control of temperature is often essential, with a particular focus on polymerase chain reaction [3] It has been popular for microfluidic flow control; thermal pumps [4] and valves [5] offer elegant solutions for device integration. They are based on thermal expansion or phase transition of specific materials. Optical actuation with low-power light patterns has been recently developed for microfluidics It offers significant advantages for device integration and parallel manipulation. This paper reports on the fabrication and characterization of newly developed optoelectronic heaters (OEH devices)
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