Bioadhesive and conductive hydrogel-integrated brain-machine interfaces for conformal and immune-evasive contact with brain tissue

Summary Brain-machine interfaces (BMIs) enable communication between the brain and external machines. However, mechanical and biological mismatches, as well as weak physical adhesion-induced shifts between rigid electronic devices and soft brain tissue, generally trigger a host immune response, affecting signal recording and reducing the lifespan of BMIs in clinics. Herein, we design a bioadhesive ultrasoft BMI based on integration of bioelectronics with a dopamine methacrylate-hybridized poly(3,4-ethylenedioxythiophene) nanoparticle (dPEDOT NP)-incorporated hydrogel with high conductivity. The hydrogel exhibits robust adhesiveness, enabling tight integration with metallic microcircuits and seamless adhesion to the brain tissue. Most importantly, the hydrogel exhibits a brain-level modulus that reduces its mechanical discrepancy with brain tissue. Meanwhile, the hydrogel possesses immune-evasive ability, which actively prevents fibrous tissue encapsulation and neuroinflammation after implantation. Consequently, the immune-evasive, bioadhesive, ultrasoft, and conductive hydrogel-integrated BMI permits long-term and accurate electroencephalographic signal acquisition and communication with minimal foreign body reaction.