Energy Conversion in Protocells with Natural Nanoconductors

Abstract

While much nanotechnology leverages solid-state devices, here we present the analysis of designs for hybrid organic-inorganic biomimetic devices, "protocells," based on assemblies of natural ion channels and ion pumps, "nanoconductors," incorporated into synthetic supported lipid bilayer membranes. These protocells mimic the energy conversion scheme of natural cells and are able to directly output electricity. The electrogenic mechanisms have been analyzed and designs were optimized using numerical models. The parameters that affect the energy conversion are quantified, and limits for device performance have been found using numerical optimization. The electrogenic performance is compared to conventional and emerging technologies and plotted on Ragone charts to allow direct comparisons. The protocell technologies summarized here may be of use for energy conversion where large-scale ion concentration gradients are available (such as the intersection of fresh and salt water sources) or small-scale devices where low power density would be acceptable.

Nano‐dielectrics in biosystems

“…The anatomical results show that the electricity-generating organ of electric eels, named electric organ, is composed of a large number of highly differentiated flat-shaped electroplate cells (also called electrocytes, with a thickness of 100 μm and a width of 1 mm). They are horizontally parallel and stacked along the spine, which constitutes the electric organ, occupying 4/5th of the body of an eel [32,54]. In resting state, there is a transmembrane voltage of −85 mV for membranes on both sides of the flat-shaped electrocyte, but no net voltage across the cell.…”

“…This capacitive energy storage mechanism of cell membranes has generated strong interest in exploring new artificial energy systems. Someone used the electric eel's discharge voltage generation mechanism to invent a power generation cell, also called protocell, that converts the chemical energy stored in the ion concentration gradient into electrical energy, as seen in Figure 6 [54]. This kind of power generation cell is composed of two droplets containing salt solutions of different concentrations.…”

“…These two effects-electromagnetic field signals and the transmembrane field/voltage reversal, respectively correspond to two different viewpoints of the physical form of neural signals. The classical cable model used by textbooks claims F I G U R E 6 Bionic power generation protocell [54] them as the ionic current signals [48], while many other models demonstrate that the neural signals are electromagnetic wave signals [36,70,71].…”

“…F I G U R E 5 (a) The complex electric power supply system in electric eels[54] and (b) Surroundings detection with weak electric current in electric fish[4] XU ET AL.…”

Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator

“…Strong EODs facilitate hunting, prey capture, and defense, while weaker (~10 V) EODs allow electrolocation and communication 4 . Electric eels inspired the design of Volta’s first electric battery to provide constant current, provide a source of acetylcholinesterase for treating neurodegenerative diseases 5 , and recently encouraged the development of synthetic protocells with natural nanoconductors and capacitators 6,7 , and a stacked hydrogel battery that could be used to power medical implants 8 . Electric eels are also an emerging model for genomic studies of animal electrogenesis 9 .…”