The goal of nanotechnology is to build nanodevices that are intelligent, multifunctional, exceptionally small, extremely sensitive and have low power consumption. When the nanodevice is required for applications such as in vivo biomedical sensors, a nanoscale power source is required. Although a battery or energy storage unit is a choice for owering nanodevices, harvesting energy from the environment is an essential solution for building a "self-powered" nanodevice/nanosystem, which is an integration of nanodevice(s) and nano-enabled energy scavenging technologies.
Previously, nanogenerators (NGs) have been demonstrated that can convert mechanical energy of low (order of Hz) and high (around 50 kHz) frequencies into electricity by means of piezoelectric zinc oxide nanowires (NWs). A single silicon NW-based heterostructure has been used to fabricate solar cells that are effective for driving an NW-based pH sensor or logic gate. These comments come from Adv. Mater. 2010, XX, 1-5, where scientists from Tsinghua University and The National Center for Nanoscience and Technology of China, and Georgia Institute of Technology in the USA, argue that the most abundant energy available in biosystems is chemical and biochemical energy, such as glucose. In this paper, they report a nanowire NW-based biofuel cell (NBFC) based on a single proton conductive polymer NW for converting chemical energy from biofluids, such as glucose/blood, into electricity, using glucose oxidase and laccase as catalyst. This nano biofuel cell is based on an electrochemical process of converting glucose into gluconolactone. The glucose is supplied from the biofluid and the NW serves as the proton conductor. A net current is generated due to the chemical potential difference between the anode and cathode as a result of the respective chemical reactions at those electrodes.
The NBFC of a single NW generates an output power as high as 0.5-3 micro watts and has been integrated with NW-based pH, glucose or photon sensors for performing self-powered sensing. Such performance can be largely enhanced and scaled up with the integration of multiple nanowires.
The NBFC provides "a new approach for self-powered nanotechnology that harvests electricity from the environment for applications such as implantable biomedical devices, wireless sensors, and even portable electronics that are important for biological sciences, environmental monitoring, defense technology and even personal electronics," say the authors. It is "sufficient to drive pH, glucose or photon sensors. The high output power, low cost and easy fabrication process, large-scale manufacturability, high 'on-chip' integratability and stability demonstrates its great potential for in vivo biosensing."
Top image source: University of Pennsylvania
For more read : Energy Harvesting and Storage for Electronic Devices 2010-2020
