Technology Partnership Office
100 Bureau Drive, M/S 2200
Gaithersburg, MD, 20899
Complex nanostructure fabrication resulting in the first 3D nanofluidic device for on-chip, high-resolution, high-range, high-throughput nanoparticle sorting and metrology
Nanofluidic structures are usually fabricated by etching a channel pattern into a glass or silicon wafer with the same procedures used to manufacture circuit patterns on computer chips. Because of the limitations inherent to conventional nanofabrication processes, almost all nanofluidic devices to date have had simple geometries with only a few depths. This limits their ability to separate and measure mixtures of nanoparticles with different sizes or study the nanoscale behavior of biomolecules (such as DNA) in detail. Other types of lithographic nanostructures have been similarly limited in form and function by planar fabrication processes.
To solve this problem, NIST and Cornell University researchers teamed up to develop a process to fabricate nanostructures with complex three dimensional surfaces. As a demonstration of their method, the researchers constructed a nanofluidic chamber with a "descending staircase" geometry etched into the floor.
3D Nanofabrication Process
The 3D Nanofabrication Process utilizes a single layer of grayscale photolithography in conjunction with a novel nanoscale pattern transfer procedure to build 3D nanofluidic devices. This enables the fabrication of nanostructures with numerous depths controlled with nanometer precision across the nanometer length scale over large substrate areas.
Nanoparticle Sorting Device
The fabricated 3D nanofluidic device has a "staircase" structure for sorting nanoparticles. Each "step" in this staircase gives the device a progressively increasing depth from 10 nanometers (approximately 6,000 times smaller than the width of a human hair) at the top to 620 nanometers (slightly smaller than an average bacterium) at the bottom. This gives the device the ability to manipulate nanoparticles by size in the same way that a coin sorter separates nickels, dimes and quarters.
A.) Schematic of 3D nanofluidic device operation B.) Fluorescence micrograph of nanoparticle size exclusion C.) Fluorescence micrograph of DNA manipulation
A nanofabrication Process for use with a photoresist that is disposed on a substrate includes the steps of exposing the photoresist to a grayscale radiation pattern, developing the photoresist to remove the irradiated portions and form a patterned topography having a plurality of nanoscale critical dimensions, and selectively etching the photoresist and the substrate to transfer a corresponding topography having a plurality of nanoscale critical dimensions into the substrate.
available for licensing
Files are in Portable Document Format (PDF). You may download a reader at http://get.adobe.com/reader/