(Nanowerk News) While researchers are making major advances in medical treatments, they are also finding that the efficacy of these treatments can be increased with an individualized approach. Therefore, clinicians increasingly need methods that can continuously monitor physiological signals and then personalize responsive therapeutic delivery.
The need for safe and flexible bioelectronic devices
Implantable bioelectronic devices play an important role in these treatments, but there are a number of challenges hindering their widespread adoption. These devices require special components for signal acquisition, processing, data transmission, and powering.
Until now, achieving this capability in implantable devices required the use of various rigid and non-biocompatible components that could cause tissue disruption and patient discomfort. Ideally, these devices should be biocompatible, flexible, and long-term stable in the body. They also need to be fast and sensitive enough to quickly record low-amplitude biosignals, while still being able to transmit data for external analysis.
Columbia researchers discover the first self-contained, flexible and fully organic bioelectronic device
Columbia Engineering researchers announced that they have developed the first fully organic, self-contained, aligned bioelectronics device that can not only acquire and transmit neurophysiological brain signals, but can also provide power for the operation of the device.
The device, about 100 times smaller than a human hair, is based on an organic transistor architecture incorporating vertical channels and mini-water channels exhibiting long-term stability, high electrical performance and low-voltage operation to prevent damage to biological tissue.
These findings are outlined in a new study, published in Natural Ingredients (“Internally integrated ion gated organic electrochemical transistor for customized and stand-alone bioelectronics”).
Both researchers and clinicians recognize the need for transistors that simultaneously deliver all of these features: low operating voltage, biocompatibility, performance stability, suitability for life operation; and high electrical performance, including fast temporal response, high transconductance and crosstalk free operation.
Silicon-based transistors are the most established technology, but they are not a perfect solution because they are hard, stiff, and unable to form very efficient ion interfaces with the body.
The team tackled this problem by introducing a scalable, self-contained, sub-micron IGT (internal-ion-gated organic electrochemical transistor) architecture (vIGT). They incorporate a vertical channel arrangement that adds to the intrinsic speed of the IGT architecture by optimizing the channel geometry and enabling side-by-side arrangement of high-density transistors – 155,000 of them per square centimeter.
Scalable VGIT is the fastest electrochemical transistor
VIGT consists of commercially available biocompatible materials that do not require encapsulation in a biological environment and are not disturbed by exposure to water or ions. Duct composite materials can be reproduced in large quantities and can be solution-processed, making them more accessible for a variety of fabrication processes. They are flexible and compatible with integration into a wide variety of adaptable plastic substrates and feature long-term stability, low inter-transistor crosstalk, and high-density integration capacity, enabling the efficient fabrication of integrated circuits.
“Organic electronics is not known for its high performance and reliability,” said study leader Dion Khodagholy, professor of electrical engineering. “But with our new vGIT architecture, we can incorporate vertical channels that have their own supply of ions. These self-sufficient ions make transistors incredibly fast — in fact, they are currently the fastest electrochemical transistors.
To push the operating speed even further, the team used advanced nanofabrication techniques to shrink and compact these transistors at the submicro-meter scale. Fabrication took place in the Columbia Nano Initiative cleanroom.
To develop the architecture, researchers first need to understand the challenges associated with the diagnosis and treatment of patients with neurological disorders such as epilepsy, as well as the methodologies currently used. They worked with colleagues in the Department of Neurology at Columbia University Irving Medical Center (CUIMC), in particular, with Jennifer Gelinas, assistant professor of neurology, electrical and biomedical engineering and director of the Epilepsy and Cognition Lab.
The combination of high speed, flexibility and low voltage operation allows transistors to be used not only for recording nerve signals but also for data transmission as well as powering devices, leading to fully customizable implants. The researchers used this feature to demonstrate a fully malleable and verifiable implant capable of high-resolution recording and transmission of neural activity both from outside, on the surface of the brain, and inside, deep within the brain.
“This work has the potential to open up a wide range of translation opportunities and make medical implants accessible to a large patient demographic that has traditionally been ineligible for implant devices due to the complexity and high risk of such procedures,” said Gelinas.
“It’s amazing to think that our research and tools can help clinicians with better diagnoses and can have a positive impact on patients’ quality of life,” added the study’s lead author Claudia Cea, who recently completed her PhD at Columbia and will become a postdoctoral fellow. fellow at MIT this fall.
The next step
The researchers next plan to join forces with neurosurgeons at CUIMC to validate the capabilities of vIGT-based implants in the operating room. The team hopes to develop a gentle and safe implant that can detect and identify various pathological brain waves caused by neurological disorders.