Biomolecular Electronics: Protein-Based Associative Processors and Volumetric Memories

The promise of new architectures and more cost-effective miniaturization has prompted interest in molecular and biomolecular electronics. Bioelectronics offers valuable near-term potential, because evolution and natural selection have optimized many biological molecules to perform tasks that are required for device applications. The light-transducing protein bacteriorhodopsin provides not only an efficient photonic material, but also a versatile template for device creation and optimization via both chemical modification and genetic engineering. We examine here the use of this protein as the active component in holographic associative memories as well as branched-photocycle three-dimensional optical memories. The associative memory is based on a Fourier transform optical loop and utilizes the real-time holographic properties of the protein thin films. The three-dimensional memory utilizes an unusual branching reaction that creates a long-lived photoproduct. By using a sequential multiphoton process, paral...