Method for Fabricating Arrayed Light Emitting Probes for a Scanning Optical Microscope

Introduction

The resolution of conventional (far-field) optical microscopes is limited by diffraction to the wavelength of light. The shortest wavelengths are 200-300 nm. Near-field scanning optical microscopy (NSOM), a recent advancement, obtains high-resolution images (less than 100 nm) by working with probe light source diameters and probe-to-surface distances shorter than the wavelength of light.

NSOM achieves high resolution while retaining the sensitivity and flexibility of far-field optics, including the ability to perform fluorescence and polarized imaging and ultraviolet, infrared, and Raman spectroscopy. In addition, NSOM requires little sample preparation and can be performed on a wide range of subjects such as silicon chip matrices and living cells. Advanced NSOM instruments also incorporate the topographical and force data of atomic force microscopy

Commercially available NSOM probes consist of a fiber through which light from an external source is delivered to a tip with a 25-100 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. The bulkiness prevents the construction of dense arrays of nanoscale probes that would speed scanning and allow for simultaneous imaging with light of different wavelengths.

Invention Description

A dense NSOM probe array 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 trapping nanoparticles in a 10 nm aperture between silicon electrodes. The inventors are now ready to integrate this array with other silicon/MEMS functional elements, such as piezoresistive/piezoelectric force sensors, MEMS actuators, and transistor circuitry.

Benefits

• Microfabrication may provide low-cost mass production of high-quality probes
• Probe arrays will speed scanning, enabling scanning of larger areas
• Enhanced resolution
• Scans with different wavelengths of light
• Integration with other MEMS devices

Features

• Independent nanoscale light sources on probe tip
• Lock-in amplification of signal

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.

Development Stage

Lab/bench prototype completed.

IP Status

One U.S. Patent Application filed

UT Researcher

• John X.J. Zhang, Ph.D, Department of Biomedical Engineering, The University of Texas at Austin
  
• Kazunori Hoshino, Ph.D., Department of Biomedical Engineering, The University of Texas at Austin

Contact:

University os texas,
Austin, USA
Website : www.otc.utexas.edu