Neural Noise- Neural implants contain integrated circuits (ICs) built on silicon.1
- Implantable ICs need to be small and flexible to mimic conditions inside the human body.1
- The body environment is corrosive, raising concerns about the durability of implantable silicon ICs.1
- Researchers have studied degradation mechanisms of silicon ICs in the body to address this.1
- Coating silicon ICs with soft PDMS elastomers forms body-fluid barriers that can protect implants in vivo.1 1
Weekly enrichment (2026-07-20)
- The work is a TU Delft study (Bioelectronics Section, Dr. Vasiliki Giagka’s group; first author Kambiz Nanbakhsh) published in Nature Communications 2025 (16(1), DOI 10.1038/s41467-024-55298-4).2
- Silicon ICs sourced from two different commercial foundries were evaluated over one-year accelerated in vitro and in vivo (implantation) studies.2
- Each chip carried custom test structures and was partially coated in PDMS, creating adjacent “bare-die” and “PDMS-coated” regions; in vitro, chips were soaked in ~67 °C saline and electrically biased with direct current.2
- Bare-die ICs maintained stable electrical performance for at least a year with a capacitive phase near -90°, indicating the passivation and inter-metal dielectric layers had no pinholes or nano-defects that would create resistive leakage paths.2 3
- Material analysis still showed oxidation-driven degradation of the SiNx passivation in bare regions, whereas PDMS-coated regions degraded far less because PDMS adhered to the nitride and blocked water-leakage paths.2 3
- From measured passivation oxidation rates of ~3.9 nm/year (Chip-A) and ~1.4 nm/year (Chip-B) for PDMS-protected nitride, the authors conservatively estimate PDMS-coated ICs could reach decades of functional lifetime in the body.2 3
- Clinical/BCI implication: the results support designing chip-scale active bioelectronic implants for minimally invasive brain–computer interfaces and chronic neuroscience, and the authors propose encapsulation guidelines to extend implant longevity.2