Construction of 980 nm laser-driven dye-sensitized photovoltaic cell with excellent performance for powering nanobiodevices implanted under the skin

Wireless nanobiodevices (such as nanorobots) have great potential to revolutionize the diagnosis and therapeutic system for human health, but their applications have been limited by difficulties in fabricating such nanobiodevices, and one of the difficulties is to obtain an in vivo energy source as their biopower component. To address this problem, we have developed a kind of 980 nm laser-driven photovoltaic cell (980LD-PVC) by introducing a NaYF4:Yb,Er nanophosphor layer in conventional dye-sensitized solar cells, and its performance has been optimized by improving the up-conversion luminescence intensity of NaYF4:Yb,Er nanophosphors and adopting a succinonitrile-based gel electrolyte. Under the direct irradiation of a 980 nm laser with an illumination area of 2 × 8 mm2 and a safe intensity of 720 mW cm−2 that is slightly lower than the conservative limit (726 mW cm−2) for human skin exposure, 980LD-PVC without a liquid component exhibits a maximum output power of 44.5 μW and an overall 980 nm laser-to-electrical energy conversion efficiency of 0.039%. In particular, after being covered with chicken skin (thickness: 1 mm) as a model of biological tissue, 980LD-PVC still possesses a maximum output power of 22.2 μW and an overall conversion efficiency of 0.019%, which is still excellent enough to satisfy the power requirements of in vivo nanorobots (at least 1 μW) and cardiac pacemakers (about 10 μW). This research paves the way for the development of novel electrical sources to power wireless nanobiodevices and many other biodevices implanted under the human skin.