We propose to investigate the microgravity fabrication of protein-based polymer media for three-dimensional optical memories. Current fabrication methods are based on polymerization, in the earth's gravitational field, of acrylamide mixed with isolated purple membrane (bacteriorhodopsin). These gels develop protein inhomogeneities within the three dimensional framework and tend to exhibit light scattering. As a result, the reliability of both the writing and reading processes of the memory is significantly compromised. A microgravity environment should minimize buoyancy driven convection, thereby eliminating many of the difficulties we have observed. The goal of this project is to develop a homogeneous data storage medium.Briefly, the specific objectives of this project are to: (a) develop a protocol to prepare improved three-dimensional optical storage media based on polyacrylamide-bacteriorhodopsin gels; (b) test the relevent characteristics of the space processed materials, including optical distortion, scattering, protein homogeneity, and diffraction efficiency; (c) compare these characteristics to those of equivalent earth-processed materials. These objectives address the requirements of subtopic 17.04, "Commercial Space Processing", in that they seek to improve an optical electronic material for a commercial optical electronic device by using space-based fabrication.
Potential Commercial Applications:The successful processing of three dimensional optical memory media in space should have important technological and commercial consequences. Due to the efforts of a number of investigators over the past eight years, light transducing proteins, such as bacteriorhodopsin, have shown great promise as active components in opto-electronic applications. There are significant advantages inherent in the use of such biological molecules, either in their native form, or modified via chemical or mutagenic methods, as active components in electronic devices. Materials problems constitute the major obstacle in successful commercial application of materials such as bacteriorhodopsin. Given that we can overcome the materials problems, bacteriorhodopsin can be used as the photoactive element in optically coupled modulators, fourier associative processors and memory devices, random access memories, nonlinear optical three-dimensional memories and artificial retinas. In principle, a three-dimensional memory can store roughly three orders of magnitude more information in the same size enclosure relative to a two-dimensional optical disk memory.
