The market for implantable medical devices is growing steadily, driven by a surge in chronic disorders and rising consumer awareness. The pace is ably backed by technological advances, helping to make these devices more efficient, convenient, and low-cost.
Numbers suggest that the market for implantable medical devices worldwide will nearly double in a decade, from US$105.7 billion in 2023 to US$207.0 billion in 2033. Today, we will start by looking into one of the most defining innovations in this field in recent times, which is also symptomatic of the thriving space where medical physiology intersects efficient electronics.
Gold Nanowires and Soft Electrodes are Ready to Be Connected to the Nervous System
A team of researchers at Linköping University has created gold nanowires and developed soft electrodes that can work equivalent to human nerves in their stretchability, electrical conduction, and durability within the body.
Researchers and experts see immense potential in this innovation. To begin with, it opens up frontiers where it could be possible to use gold in soft interfaces to connect electronics to the nervous system for medical purposes.
If deployed correctly, this can result in alleviating conditions as complex as epilepsy, Parkinson’s disease, and paralysis and as ubiquitous a concern as chronic pain.
For quite some time now, researchers globally have been interested in creating soft electrodes that do not damage the tissue. This particular achievement by Linköping University researchers helped attain that by creating gold nanowires that were a thousand times thinner than hair and embedded in an elastic material that could work as soft microelectrodes.
Klas Tybrandt, while elaborating on the uniqueness of the research and its outcomes, had the following to say:
“We’ve succeeded in making a new, better nanomaterial from gold nanowires in combination with very soft silicone rubber. Getting these to work together has resulted in a conductor with high electrical conductivity, is very soft and made of biocompatible materials that function with the body.”
Creating Gold Nanowires: Challenges Met and Overcome
One of the major difficulties the researchers faced was regarding the production of long, narrow gold nanostructures. The researchers worked out a unique way to overcome this challenge, and that was by using silver nanowires. Explaining how this unique feat could be achieved, Klas Tybrant said the following:
“As it’s possible to make silver nanowires, we take advantage of this and use the silver nanowire as a kind of template on which we grow gold. The next step in the process is to remove the silver. Once that’s done, we have a material that has over 99 percent gold in it.”
Originally, researchers could not use silver because it is chemically reactive, wears out over time, and risks breaking down and discoloring. Additionally, high concentrations of silver can be toxic to the human body. Therefore, they had to coat it with gold.
Regarding the material they’ve devised and its durability, researchers believe their solution could last for at least three years, outperforming many previously developed nanomaterials.
Soon, the research team will start working on refining the material and creating different types of electrodes that would be even smaller and possible to bring in closer contact with nerve cells.
The Diverse World of Implantables
While the usefulness of this research has already been cited, there are many other implantables available in the med-tech space. They help make diagnosis and treatment more consistent, affordable, and efficient.
For example, scientists at Georgia Tech University have developed an implantable, wearable sensor that monitors the healing of aneurysms within the brain’s blood vessels. Because it operates without batteries, it can be wrapped around stents or diverters that are implanted to regulate blood flow.
The sensor is created using aerosol jet 3D printing, which lays down conductive silver traces on elastomeric substrates. Inserted via a catheter, it uses inductive coupling of signals for wireless detection of biomimetic cerebral aneurysm hemodynamics.
The process involves three coils. One coil captures electromagnetic energy transmitted from another coil outside the body. As blood flows through the stent, the implanted sensor changes its capacitance, altering the signal transmitted to a third external coil.
In another instance of a similar line of work, a group of engineers at Texas A&M University have developed a device that uses graphene and injects AC into the skin to monitor blood pressure.
Called Graphene Electronic Tattoos, these stickable graphene sensors can track cardiovascular health via continuous monitoring. They can continue working and collecting relevant data even when the patient is sleeping, exercising, or experiencing high-stress situations.
Research is also underway to determine how these implantable devices can harness and utilize energy. For instance, a team of Massachusetts Institute of Technology researchers has developed a battery that draws its power from glucose. The novel battery measures just 400 nanometers thick, or about 1/100th of the diameter of human hair. It generates about 43 microwatts per square centimeter of electricity and can withstand temperatures up to 600 ° C.
The researchers used an ultra-thin ceramic substrate and a glucose solution to empower the battery with flexibility and make it convenient to place within the body.
While researchers are working to come up with as many novel and unique technology solutions as possible, some companies have been working on making efficient implantable devices available for mass adoption. In the coming segments, we shall look into a couple of such commercial solutions.
#1. CorTec
One of the companies that has consistently delivered groundbreaking solutions is CorTec. An ISO 13485 company, CorTec develops and manufactures products and components for neuromodulation and active implant technology in its in-house laboratories and clean room infrastructure.
CorTec’s patented range of AirRay electrodes proves useful for stimulation and recording of the nervous tissue, serving as the ideal interfaces to the nervous system for medical devices.
For instance, the AirRay cuff electrodes provide an electrical interface to the peripheral nervous system, whereas the grid and strip electrodes are designed for interfacing with the central nervous system. The AirRay percutaneous electrodes are intended for subcutaneous use, as well as for recording and stimulating the spinal cord. Lastly, the AirRay paddle electrodes offer an electrical interface to the central nervous system, specifically targeting the spinal cord.
Apart from this range, one of CorTec’s patented solutions also includes its Cortical Electrodes. These are CorTec’s ECoG electrodes for invasive neuromonitoring. Through these electrodes, it is possible to carry out the monitoring of electrical brain signals, which is in line with the requirements of the localization of epileptogenic foci or brain mapping. The electrodes can be used for a maximum of 29 days, and it is possible to connect a total of 64 electrodes using only two cables. The electrode contacts are nearly impalpable and lock safely with the material to prevent their separation from the silicone.
One of the most crucial aspects of CorTec’s cortical electrodes is that the FDA has found it fit for approval and market clearance for invasive neuromonitoring in the central nervous system. The product portfolio includes all possible contact arrangements from 1×4 to 8×8 electrode contacts.
Apart from significant public funding, CorTec, as per its official declaration, has raised four rounds of financing. Its list of current investors includes Mangold Invest, M-Invest, Kfw, High-Tech Gruenderfonds, Santo Venture Capital GmbH, LBBW Venture Capital, and K & S W Invest.
The public funding includes subsidies from the German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung, BMBF) and the European Union.
#2. Atrotech
Another firm that has been doing somewhat niche yet game-changing work in this space for decades is Atrotech. Founded in 1984 and located in the Technopolis Hermia, Tampere, Finland, Atrotech emerged as a result of interdisciplinary product ideas that combined the medical and bioengineering sciences, with the main focus of activities being in the field of functional electrical stimulation (FES).
Two of Atrotech’s major contributions in this field include the designing and manufacturing of implantable neurostimulators and implantable electrodes.
In devising the electrodes, the company leverages its more than 30 years of expertise in manufacturing high-quality platinum contact electrodes, lead wires, and multipole lead connectors. The service area it caters to includes research projects, clinical trials, and commercially distributed medical devices.
The company has a flexible production process, enabling it to manufacture small quantities as well as larger scale volumes in a rapid, cost-effective manner. Additionally, the company is in touch with multiple physicians and universities in the early stages of the development and prototyping of potential new medical devices.
One of the studies the company recently funded was aimed at assessing the feasibility and safety of a novel, removable, surgically implanted, temporary neurostimulation approach involving the distal portion of the phrenic nerve. For the study, the company developed a specially designed, temporary phrenic nerve stimulator (tPNS) electrode.
Such collaboration between specialist and industry-focused companies and a band of researchers and physicians spread across the globe makes the future of internal electronics appear bright and ready to flourish.
The Future Trajectory of Internal Electronics
According to a recent research published in July 2024 in the journal ‘Nature’, researchers have developed an implantable electrode based on bioresorbable Mg-Nd-Zn-Zr alloy which would work well in a next-gen radiofrequency (RF) tissue welding application.
The electrode is expected to bring down thermal damage and increase anastomotic strength. Designed with different structural features of cylindrical surface (CS) and continuous long ring (LR) in the welding area, the electrode’s electrothermal simulations were studied by finite element analysis (FEA).
The results showed that the mean temperature in the welding area and the proportion of necrotic tissue became significantly less when applying an alternating current of 110 V for 10 seconds to the LR electrode. The maximum and mean temperatures of tissues welded by the LR electrode could also be significantly reduced while the anastomotic strength of welded tissue improved.
Imec, a lab founded in 1984 to assist and enable the semiconductor industry to functionally scale, has also made some pioneering breakthroughs in nano-scale implantables. It has helped develop minimally invasive implants suited for next-generation haptic prosthetics. The prototype implantable chip that Imec has developed together with the University of Florida gives patients more intuitive control over their arm prosthetics. One of its major components, the thin-silicon chip, is the world’s first for electrode density and was developed as part of the IMPRESS project funded by DARPA’s HAPTIX program to create a closed-loop system for future-generation haptic prosthetics technology.
One of the scientific publications on the importance of carbon-based implantable bioelectronics made a crucial observation on the usefulness of internal electronics. To quote verbatim, the publication observes:
“Because implantable bioelectronics can sense bodily information or elicit bodily reactions in living creatures from sites outside the body, they are becoming helpful and promising remedies for a variety of ailments.”
In the future, carbon materials will play a crucial role in manufacturing implantable medical electronics. These advantages include carbon materials’ high-grade biocompatibility, fatigue resistance, and low specific gravity. These materials are used in a wide range of applications, including drug delivery devices, biosensors, therapeutic stimulators, and energy storage. All these properties have a role to play in the fields of neurological, cardiovascular, gastrointestinal, and locomotor systems.
Implantable actuators, biosensors, drug delivery systems, and power supplies—all benefit from advancements in the field of internal or implantable electronics. Further progress in this area will require a more intersectional approach involving bioscience researchers, material scientists, and physicists worldwide.
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