Scientists have engineered a compact, biologically compatible energy source that draws its inspiration from electric eels to stimulate human nerve cells directly. This development has potential utility in areas like targeted drug administration, accelerated wound healing, and bio-hybrid apparatuses.
A team of researchers from the University of Oxford has made a significant stride in the development of small bio-integrated devices capable of directly interacting with cellular structures. The findings were recently disseminated in the esteemed scientific journal, Nature.
One of the principal hurdles in the implementation of these small bio-integrated devices has been the absence of an efficient microscale power source—a challenge that has yet to be effectively surmounted until now. To tackle this issue, scientists from the Department of Chemistry at the University of Oxford have devised a compact energy source that is capable of modulating the activity of cultivated human neural cells. Drawing inspiration from the electric generation capabilities of electric eels, the technology employs internal ionic gradients to produce energy.
For visualization purposes, the study showcased an enlarged depiction of the droplet power source. Encased in a flexible, compressible organogel, the droplets had a volume of 500 nL. On the other hand, a standard-sized droplet power source was made up of 50 nL droplets. Both depictions were provided with scale bars for accurate measurement.
The compact soft energy source was fabricated by laying down a sequence of five nanolitre-scale droplets of a conductive hydrogel—a three-dimensional lattice of polymer chains infused with a substantial quantity of water. Each droplet features a distinct chemical composition, establishing a salt concentration gradient across the sequence. Lipid bilayers separate these droplets, providing mechanical integrity while inhibiting ionic interchange between them.
Activation of this power source occurs by cooling the assembly to 4°C and altering the surrounding medium. This process disrupts the lipid bilayers, leading to the formation of a continuous hydrogel. Consequently, ions are able to traverse the hydrogel, moving from the high-salt end droplets to the low-salt central droplet. By connecting electrodes to the end droplets, the energy emanating from the ionic gradients is converted into electrical power, thereby enabling the hydrogel to function as an external power source.
The study revealed that the activated droplet-based power source sustained a current for more than half an hour. The maximum energy output for a unit constituted of 50 nanolitre droplets was approximately 65 nanowatts (nW). Even after 36 hours of storage, the devices maintained a comparable level of current output.
To demonstrate the potential applications of this energy source, the research team affixed it to droplets filled with human neural progenitor cells, marked with fluorescent dye. Time-lapse recordings revealed intercellular calcium signaling in the neurons, induced by the local ionic current, when the power source was activated.
Dr. Yujia Zhang, the lead investigator of the study from the Department of Chemistry, University of Oxford, stated, “This miniaturized soft energy source represents a landmark achievement in the realm of bio-integrated devices. Utilizing ionic gradients, we have fashioned a small, biocompatible system that can regulate cellular and tissue activity on the microscale, thus expanding a broad spectrum of potential applications in both biology and medicine.”
The researchers highlighted that the modular structure of the device allows for the amalgamation of multiple units to enhance the voltage and/or current generated. Such a configuration paves the way for future technologies including wearable devices, bio-hybrid interfaces, implants, synthetic tissues, and micromachines. By stringing together 20 five-droplet units in series, the team managed to power a light-emitting diode requiring about 2 volts. They anticipate that automated production techniques, such as droplet printers, could fabricate droplet networks comprising thousands of such power units.
Professor Hagan Bayley, who led the research group for the study from the Department of Chemistry, University of Oxford, stated, “This research confronts the crucial question of how bio-compatible devices can interact synergistically with living cells. The implications for apparatuses like bio-hybrid interfaces, implants, and micromachines are considerable.”
Reference: “A microscale soft ionic power source modulates neuronal network activity” by Yujia Zhang, Jorin Riexinger, Xingyun Yang, Ellina Mikhailova, Yongcheng Jin, Linna Zhou, and Hagan Bayley, was published on 30 August 2023 in the journal Nature.
DOI: 10.1038/s41586-023-06295-y
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Frequently Asked Questions (FAQs) about Bio-Integrated Energy
What is the innovation presented in the text?
Researchers have introduced a groundbreaking innovation involving miniature bio-integrated devices powered by hydrogel droplets, inspired by electric eels. These devices can directly stimulate human nerve cells.
How do these bio-integrated devices function?
The devices utilize a chain of nanolitre-sized hydrogel droplets with varying compositions, creating a salt concentration gradient. These droplets are separated by lipid bilayers, enabling ionic movement through the hydrogel. By cooling the structure and altering the surrounding medium, the droplets form a continuous hydrogel, releasing energy from ionic gradients that can be converted into electricity.
What are the potential applications of these devices?
The applications are diverse, including targeted drug delivery, accelerated wound recovery, and the regulation of cellular activity. These devices could power wearable technology, bio-hybrid interfaces, implants, synthetic tissues, and microrobots.
How long can these devices generate power?
The activated droplet-based power source has been observed to sustain a current for over 30 minutes. Even after being stored for 36 hours, the devices maintain a comparable level of current output.
How are living cells connected to these devices?
Living cells are attached to one end of the device, allowing their activity to be directly modulated by the ionic current generated by the hydrogel droplets. This was demonstrated with human neural progenitor cells, showing waves of intercellular calcium signaling induced by the local ionic current.
What significance does this innovation hold?
The miniaturized soft energy source represents a significant advancement in bio-integrated devices. By harnessing ion gradients, researchers have developed a biocompatible system for cellular and tissue regulation on a microscale, opening up a wide array of potential applications in biology and medicine.
Could these devices be scaled up for more power?
Yes, the modular design allows for the combination of multiple units to increase voltage and current generation. By connecting 20 five-droplet units in series, researchers were able to power a light-emitting diode. Automated production methods could lead to networks composed of thousands of power units.
3 comments
gr8 blend of tech n biology, could dis lead to micro bots in crypto?
bio gizmos powerd by gel droplets? kewl stuff, opens biz opps 4 sure.
wow, this thing bout tiny power droplets & cells is amazin’! bio devices rulz!