Application of Photosynthetic Proteins in a Field-Effect Transistor for Low Light Intensity Detection

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The objective of this award is to develop a new optical sensor using photosynthetic proteins as ultra-photosensitive elements. Ultra-sensitive photo-detectors are required for making night vision digital cameras and sensitive lab-on-a-chip devices. Due to the low sensitivity of the silicon-based pixel sensors, an external illumination source (i.e. flash) is usually required for photography in low light conditions with a digital camera. The light source affects the image quality (by reflection, loss of shadows, etc.) and consumes more power. A matrix of highly sensitive photo-transistors can be used in the next-generation cameras to enhance image qualities for medical, industrial, and security applications. In contrast to silicon, photosynthetic reaction center (RC) proteins are able to detect and respond to a few photons, emitted or reflected by individual molecules. In this research a well aligned layer of RCs will be employed in a field-effect transistor (FET) to make ultra-sensitive photo-detectors. In addition to the low light intensity imaging applications, this particular type of sensor can be used for detection of contaminants in water or labeled viruses in a lab-on-a-chip device. The proposed research will impact several areas such as nanotechnology, biotechnology, and electronics, ranging from material characterization to device development. This research will help to understand the interaction of biomaterials in synthetic structures. Also, the knowledge will be useful to design and optimize other bio-electronics devices.Employing the novel mechanism of charge photo-generation in photosynthetic proteins, field-effect transistors will be fabricated using the proteins as the secondary gate of the devices. Two different devices made of thin film silicon and single wall carbon nanotubes (CNTs) will be studied for the protein attachment and building the photo-transistors. In this work it is planned to study the immobilization approaches for binding the proteins to CNTs and silicon with specific orientations and to investigate the field effect in the protein-insulator-semiconductor structures. Ultimately, the fabricated device will be employed as an optical sensor in a lab-on-a-chip device. Both experimental and theoretical studies will be carried out to understand the limitations in using the field effect from a protein as a signal for modulating carriers in a semiconductor device. Also, the study of the protein-insulator-semiconductor structure will provide more insight to the challenges for using biological materials in electronic devices and will be transferable to other applications such as bio-solar cells and bionic eyes.