Protein-based optical transducer for mechatronic devices

Abstract

An optical transducer based on the light modulated transmission properties of bacteriorhodopsin (bR) film is described in this paper. The bR protein molecules undergo a complex photocycle when absorbing light energy that is characterized by several measurable states. The most relevant states in the photocycle for this application are the initial B state (λ max = 570 nm) and the longest lived M intermediate state (λ max = 410 nm). If a yellow light source with a wavelength of approximately 570 nm and a second deep blue source at 410 nm illuminate the same region of the thin bR film, the two beams will mutually suppress the optical transmission properties of the thin film and reduce the intensity of the light output. The suppression-modulated transmission mechanism of the bR polymeric film is, therefore, controlled by the intensity and wavelength of the two light sources. Based on this simple mechanism, a number of different protein-based optical devices have been proposed in the literature for optical signal and information processing. The focus of this research is to exploit the light transmission properties of the bR film to develop efficient optical transducers that can be easily interfaced with micro-electro-mechanical systems for mechatronic applications. The proposed transducer design is activated by an external light source and free from electrical noise. Illustrations of how thin bR film can be used for the modulation of light intensity, optical switches, and logic gates are presented.