As part of the UK Health Technology Strategy, the Research Council for Physical Sciences and Research launched a competition in 2016 to identify promising research projects that address complex issues. Among the eight winners announced in 2017, Dr. Ing. Rylie Green of Imperial College London and dr. Frankie Rawson of the University of Nottingham.
Dr. Green’s efforts are focused on the bioelectronics of implantable polymers for devices such as bionic eyes and cochlear implants. The aim is to create a soft and flexible conductive polymer.
“Cochlear implants currently have 22 channels of stimulation – a limitation caused by their being made of metals,” Dr. Green. “The metal conducts electricity with the help of electrons while the body uses ions, and the equipment we use can conduct electricity using both.
“The metal limits the size,” she continued. “You can not reduce the size of the device without compromising safety, and you can not push more current through the metal, as this can lead to unwanted chemical reactions, such as changes in the pH of the tissue.
The polymer material allows the current to be forced into the body at a higher rate, more efficiently, and at a lower voltage, thereby significantly reducing the risk of electrical modification or degradation.
“This allows for a better perception of sound for a cochlear implant patient or allows a person with a bionic eye to see not only 40 or 60 points of light – which is the current limit of metal electrodes – but hundreds and thousands of bright spots. ”
Dr. Green’s other challenge was to develop a polymer that could be accepted by the body. This involved modifying the properties of conductive polymers to create a flexible interface that interacts more easily and reduces the reaction of the foreign body. According to Dr. Green achieved this by hybridizing a conductive polymer with hydrogels and elastomers.
The Dr. Green developed bionic eye contains a camera suitable for sunglasses, which is connected to a processor that converts the analog signal into a digital format, which is then transmitted to the body. The electronic package is located behind the ear under the skin. An electrode wire is inserted into the eyeball where it can stimulate cells to create a visual perception. A chip interprets the received information.
“The metal limits the size, you can not make the device smaller without compromising safety.”
Dr. Rylie Green
The implants are powered by inductive coils. We stay outside the body, with a corresponding coil inside. If it is magnetically assembled, it can be used for data transmission.
“A wireless inductive connection feeds the implant, sends it processed information, and receives inverted telemetry data on how the device works in the body,” said Professor Nigel Lovell of the University of New South Wales. South. Professor Lovell, who led an R & D program for the development of retinal neuroprosthesis; Green said, “The chip encodes the camera’s image information into electrical impulses, the brighter the image, the greater the amplitude of the electrical impulses, there are 99 electrodes in our graph, more electrodes means better visual acuity.
Dr. Greens polymer material will coat the electrodes to make them more efficient and possibly allow devices with more electrodes, which is not possible with metal electrodes.
“The electronic box (where data transfer and signal generation takes place) is located away from the sensory organ (eye or ear), but the interface electrode assembly must be implanted in contact with the cells. Green.
“There are 99 electrodes in our series, more electrodes means better visual acuity.”
Professor Nigel Lovell
“The more trails and channels, the better the patient experience, once you have reached the substance, you must be able to stimulate and separate these channels.
According to Green, it is difficult to ensure that polymer-based webs carry electricity over these lengths, hence the development of new polymer chemistry and manufacturing techniques.
“Hydrogels are best for interacting with tissues when they try to stimulate them, but elastomers are needed to create long runs, and the biggest challenge is to create a continuous electrical path that does not break with the movement. We did it, but we have to make it commercially competitive. ”
Bioelectronics seems to play a role in future medicine, and during Dr. Dr. Green is working to improve the audiovisual perception of diseased cells. Rawson uses bioelectronics to communicate with radio cells.
Instead of implanting an electronic device near the nerve tissue and using a current to modulate cellular proteins and stimulate communication, Dr. Ing. Rawson other projects.
“By introducing electric fields, we plan to modulate electron transfer, which can then be used to detect and activate chemical reactions, and we’ve shown that cancer cells eliminate and metabolize electrons faster and grow faster than normal tissue If we can electrically modulate this stream of external electrons, we may be able to treat cancer. ”
There are three treatment methods Dr. Ing. Rawson wants to handle.
“Initially, we plan to develop nanotechnology and use nanoparticles / microleity functionalized with a bioactive molecule that absorbs these nanoparticles, and when an external electric field is applied, the oxidation-reduction state on the surface of that nanoparticle becomes When the state of the bioactive molecule changes, it causes a change in cell metabolism and tells it to kill itself.
“Second, we believe that the use of wireless electrochemistry to self-assemble brain tumors can inhibit cell proliferation, which should theoretically prolong the patient’s life.
“Third, we plan to use artificial conductive porins.”
Porins – a type of protein – form channels through cell membranes that are large enough to allow ions to pass through. “The basis of many electrical discussions between cells is the opening or closing of pores, depending on the electric fields,” he continued. “We think we can influence the potential of cells and, consequently, the way they communicate by using artificial conductive channels and applying external electric fields.”
“If you can electronically modulate the external flow of electrons, we may be able to treat cancer.”
Dr. Frankie Rawson
These conductive wires are produced by printing electrode systems on a glass substrate. When printing with conductive inks, Dr. Rawson noted that an electrochemical reaction caused the diffusion of atoms into the solution and self-assembly into nanoparticles. These are then aligned with the conductive bipolar electrode, which has no physical connection to the circuit, thereby creating lead wires.
Current bioelectronic therapies require standard electronic materials that require invasive surgery. Dr. Rawson suggests “potentially developing in-situ electronic devices and avoiding the use of this intervention”.
He said there was “no current commercial example of cancer treatment, as we suggest”, but it is likely that this technology could be developed and applied over the next 10 years.
Dr. Rawson’s vision is a wearable device like a dermal patch that modulates the electric field and targets the area of the disease. The next step is to develop a device to modulate this electrical behavior and thus control cell proliferation and communication.
An experimental device for inducing microelectrochemical wireless growth
Although bioelectronics seems to have many benefits, there is still no mass market for technology. Mr. Green’s conclusion is due to a combination of “high costs and regulation”. But she remains optimistic and believes that the demand and growth of this technology will soon find commercial applications.