Fiber-focused diode-bar optical trapping for microfluidic manipulation
Inventors
Squier, Jeff • Marr, David W. M. • Applegate, Robert • Vestad, Tor
Assignees
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Publication Number
US-9878326-B2
Publication Date
2018-01-30
Expiration Date
Abstract
The direct integration of light and optical control into microfluidic systems presents a significant hurdle to the development of portable optical trapping-based devices. A simple, inexpensive fiber-based approach is provided that allows for easy implementation of diode-bars for optical particle separations within flowing microfluidic systems. Models have also been developed that demonstrate the advantages of manipulating particles within flow using linear geometries as opposed to individually focused point traps as traditionally employed in optical-trapping micromanipulation.
Core Innovation
An optical trapping device is disclosed that integrates a diode laser bar emitter with a microfluidic channel comprising a microfluidic flow having particles therein. The device further includes a fiber optic element positioned between the diode laser bar emitter and the microfluidic flow to receive a laser beam emitted from the diode laser bar emitter and to focus the laser beam on at least one particle flowing within the microfluidic flow.
The disclosure describes focusing the diode-bar output through a fiber optic element having a diameter of about 1 mm, with the fiber positioned substantially perpendicular to the microfluidic flow to form a linear trapping geometry. In the described implementation, a diode laser bar at about 808 nm with a square beam profile is focused into the line-trap geometry to manipulate and/or separate particles in the microfluidic channel.
The document reports that trapping forces can be experimentally determined by comparing trapping behavior while adjusting flow-rate conditions, and it compares the measured trapping force to modeling of restoring forces using ray optics and Gaussian beam stress integration. The line-trap configuration is reported to achieve equivalent trapping force at reduced local intensity and to present reduced risk of cell damage and hydrodynamic effects described as pushing fluid toward lower-velocity streamlines.
Claims Coverage
The independent claim set is centered on an optical trapping device with a diode laser bar emitter, a microfluidic channel carrying particle flow, and a fiber optic element positioned between them to focus the laser beam onto flowing particles. The claim family further adds specific beam and fiber characteristics and trap angles relative to the microfluidic flow direction.
Fiber-focused diode-bar optical trapping in microfluidics
An optical trapping device comprising a diode laser bar emitter, a microfluidic channel comprising a microfluidic flow with particles therein, and a fiber optic element having a diameter of 1 mm positioned between the diode laser bar emitter and the microfluidic flow to receive a laser beam emitted from the diode laser bar emitter and to focus the laser beam on at least one particle flowing within the microfluidic flow.
808 nm diode-bar emission for particle trapping
The diode laser bar emitter emits a laser beam with a wavelength of about 808 nm.
Square-profile beam from the diode laser bar emitter
The diode laser bar emitter emits a laser beam having a square profile.
Polymethyl methacrylate fiber optic element
The fiber optic element is made at least in part from polymethyl methacrylate material.
Substantially perpendicular fiber orientation to microfluidic flow
The fiber optic element is oriented substantially perpendicular to the microfluidic channel and to the microfluidic flow direction.
Discrete trap angle relative to microfluidic flow
The trap angled relative to the microfluidic flow is configured at one of 0°, 20°, 30°, 45°, or 60°.
Overall, the claims cover an optical trapping device that uses a diode laser bar emitter and a microfluidic channel, with a 1 mm diameter fiber optic element positioned between the emitter and microfluidic flow to focus the laser beam onto flowing particles, further refined by 808 nm square-profile emission, polymethyl methacrylate fiber material, substantially perpendicular fiber orientation, and discrete trap angles relative to the microfluidic flow.
Stated Advantages
Reduced risk of cell damage.
Hydrodynamic effects described as pushing fluid toward lower-velocity streamlines.
Equivalent trapping force can be achieved at reduced local intensity (line-trap versus spot-case).
Documented Applications
Manipulation and/or separation of particles in a microfluidic channel using an optical trapping geometry formed by focusing a diode laser bar through a fiber optic element.
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