Method for Fabricating Arrayed Light Emitting Probes for a Scanning Optical Microscope
The resolution of conventional (far-field) optical microscopes is limited by diffraction to the wavelength of light. The near-field scanning optical microscope (NSOM), a recent advancement, obtains high-resolution images (typically 80-200 nm) by using probe light source, whose size and probe-to-sample distance is shorter than the wavelength of light. NSOM has the ability to perform fluorescence and polarized imaging and ultraviolet, infrared, and Raman spectroscopy.
Commercially available NSOM probes consist of a fiber through which light from an external source is delivered to a tip with an 80-200 nm aperture. The probes are still made by hand, an inefficient manufacturing process, and the fibers are bulky, with a diameter of 80-100 micrometers. These drawbacks have prevented the NSOM from being used in further commercial applications such as nano-scale patterning and optical data storage devices.
Invention Description Researchers at The University of Texas at Austin have built a dense NSOM probe array that has been developed using micro-electro-mechanical systems (MEMS) fabrication technology. Each probe in the array is also a nanoscopic light-emitting diode (LED) configured to emit light of a different wavelength from other probes in the array. The LED is created by deposition of nanoparticles at the very tip of the silicon scanning probe.
The most significant advantage of the probe is its compatibility with several mass-producing techniques such as CMOS and MEMS fabrication processes. The probe will be used not only in conventional NSOM, but in any kind of industrial or commercial applications of high-resolution optical microscopy the probe can be tailored to fit in several possible devices. For example, it will be used in standard AFM setups, which are very widely used. The inventors are also ready to integrate this array with other silicon/MEMS functional elements, such as piezoresistive/piezoelectric force sensors, MEMS actuators, and transistor circuitry.
The other advantage is the very high resolution with several emission wavelengths from near UV to IR. This provides the future patterning tools in nano-fabrication or recording functions to compact digital devices.
Silicon-microfabrication may provide low-cost mass production of high-quality probes. Probe arrays will speed scanning, enabling scanning of larger areas. Enhanced resolution of 20-50nm means better acuity. Self-illuminating MEMS probe tip allows integration of self-content compact digital devices. Different emission wavelengths of light ranging from near UV to near-IR (sees in multiple colors) Can also be used in patterning and recording devices Ready to integrate with other silicon/MEMS functional elements
Integrated nanoscale light source on tip of a scanning MEMS probe Lock-in amplification of signal Molecular-scale sensitivity Inexpensive, disposable, small-form factor probe array Can be used in existing AFM setup and other microscopy Provide a resolution beyond diffraction limit to several existing tools
Market Potential/Applications This NSOM probe array is ready for many research and manufacturing process applications, including but not limited to imaging molecular semiconductor heterostructures, laser diodes, and cell membranes; analyzing the structure of organic thin films and polymer blends, and drug-receptor interactions; viewing nanotubes, quantum dots, and other nanomaterials during their synthesis or use.
This MEMS probe is compatible with standard AFM systems as well as specialized NSOM imaging systems. It will open several new opportunities in biomedical and industrial applications of near-field microscopy, which so far has been limitedly used in scientific applications
In addition, Dr. Zhang has received $500K in NSF funding to further this development.
Development Stage Lab/bench prototype
IP Status One U.S. patent application filed
UT Researcher Xiaojing (John) Zhang, Ph.D., Biomedical Engineering, The University of Texas at Austin Kazunori Hoshino, Ph.D., Biomedical Engineering, The University of Texas at Austin
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