Biosensors development using nanomaterials provides promising approaches to offer high performance of sensors in resolution and detection limits. Renewable energy development is attracting interests as an alternative to other sources of energy such as fossil fuels and nuclear energy. Therefore, if biosensor systems can be integrated with nanomaterials and photovoltaics, this biosensor platform can detect various biotargets and support itself by solar energy harvesting with better performance and lower cost. It can reduce cost and pollution from battery or electrical power in a green strategy. It will bridge technological advances in multidiscipline to address fundamental emerging issues in applied science and engineering.A flexible biosensor based on "bottom up" layer-by-layer self-assembled graphene is investigated. This graphene biosensor can detect different concentrations of biotargets (e.g., glucose, vascular endothelial growth factor, acetylcholine) as a detection platform by measuring the conductance change of the self-assembled graphene. After optimizing of the biosensor structure and dimensions, the suspended graphene sensors are capable of detecting very low concentrations of prostate specific antigen down to 0.4 fg/ml (4×10-16 g/ml), showing a great advantage over conventional testing methods with only 0.4 ng/ml (4×10-10 g/ml) detection limit.To fabricate solar cell power source, a simple, rapid and robust approach to controllably create nanostructures on a shrink polymer substrate photocathode, demonstrating a 34.1% enhancement of energy conversion efficiency for dye-sensitized solar cells (DSSCs). Glass photoanodes are also replaced with patterned shrink polymer substrates to form the flexible all-polymer DSSCs. A low-cost shrink lithography technique with 21 nm resolution to support the nanostructure fabrication of biosensor and solar cell in a low-cost way. By using this novel lithography technique, a biosensor based on suspended graphene nanoribbon with only 50 nm width was successfully fabricated. This shrinkage strategy was extended to the fabrication of tunable micro/nano structures with very low cost. These shrink induced micro/nano structures are tunable and controllable on the material properties (e.g. conductance, surface wetting ability, surface morphology), which offering more controllable and flexible applications to biochemical detection and energy harvesting with simple and low cost strategy.