Revolutionary Breakthroughs in Neural Implant Durability: Redefining the Future of Brain-Machine Interfaces

Essential research on brain disorders

Neural implants play a vital role in exploring the brain and developing therapies for individuals with conditions such as Parkinson’s disease or clinical depression. These implants electrically stimulate, obstruct, or record signals from neurons or neural networks within the brain. For both study and treatment purposes, particularly in chronic usage, it is essential that these neural implants exhibit durability.

“Miniaturized neural implants possess remarkable potential to revolutionize healthcare, yet their long-term reliability within the body remains a significant concern,” remarks Vasso Giagka, researcher at the Technical University Delft. “Our research not only identifies key challenges but also offers practical recommendations to improve the dependability of these devices, bringing us closer to secure and enduring clinical options.”

The research team assessed the electrical and material properties of chips (from two distinct manufacturers, also referred to as foundries) over a year through accelerated in vitro and in vivo studies. They utilized bare silicon IC structures and integrated them with soft PDMS elastomers to construct barriers against body fluids that afford long-term protection to implantable chips. The chips examined in the study were partially covered in PDMS (polydimethylsiloxane), which is a silicon-containing polymer. This resulted in two areas on the chips: a ‘bare die’ area and a ‘PDMS-coated’ area. During the accelerated in vitro study, the chips were immersed in heated saltwater and subjected to electrical biasing (applying direct electric currents). The chips were routinely monitored, and results indicated stable electrical performance. This demonstrated that the chips remained functional, even when directly exposed to bodily fluids.

Material analysis of the chips disclosed that degradation occurred in the bare regions, while minimal degradation was observed in the PDMS-coated areas.

This indicates that PDMS serves as an excellent encapsulant for long-term implantation. These findings will inform and facilitate the design of cutting-edge chip-scale active bioelectronic implants for minimally invasive brain-computer interfaces and ongoing neuroscientific research. Additionally, based on these new insights, guidelines are suggested that may enhance the lifespan of implantable chips, thus broadening their applications within the biomedical domain.

Surprised researchers

“We were all taken aback,” states PhD student Kambiz Nanbakhsh, who is the primary author of this study. “I did not anticipate microchips being so resilient when soaked and electrically biased in heated saltwater.”

Vasso is equally enthusiastic about the outcomes of the research. “Our discoveries reveal that bare-die silicon chips, when meticulously designed, can function reliably in the body for months. By tackling long-term reliability challenges, we are unlocking new possibilities for miniaturized neural implants and propelling the advancement of next-gen bioelectronic devices for clinical applications.”

Vasso underscores the protective function of PDMS. “This study highlights the significant role of silicone encapsulation in protecting implantable integrated circuits from degradation. By prolonging the lifespan of neural implants, our research paves the way for more durable and efficient technologies for brain-computer interfaces and medical therapies.” Kambiz fully concurs with Vasso: “This was an extensive investigation, but we hope the findings will benefit many.”