Friend, Not Foe: Lowered Tissue Reactivity to Long-Term Polyimide Implants
Journal article, 2026
One of the biggest challenges for neurotechnology is the design of devices that are tolerated well by brain tissue, without sacrificing functionality and implantability. This study examined which design choices mitigate tissue damage and improve longevity by varying probe features implanted in the cerebral cortex of mice. We report on a systematic, quantitative analysis of neuronal and inflammation markers across cortical depth. We implanted a total of 103 stiff silicon or flexible polyimide probes in 32 mice, varying their thicknesses and widths, and either attaching them to the skull or not. A new, automated workflow to quantify immunohistochemical data examines: 1) the tissue loss caused by the implant, 2) the cortical neuronal density, and 3) the immune response expressed by astrocytic and microglial reaction. Flexible polyimide probes exhibited a clear advantage, causing fewer lesions and weaker immune responses than stiff silicon probes. Furthermore, we observed a weak influence of the shank cross-section. A cortical depth profile of immune reactivity revealed focal reactions at the device entry points in the superficial cortex and at the cortex-white matter boundary. This study gives important insights on optimizing device design parameters as well as surgical insights for improved tissue integration of intracortical electrode arrays.
foreign body response
intracortical electrodes
biocompatibility
histology
neurotechnology
Author
Corinne Orlemann
Netherlands Institute for Neuroscience NIN - KNAW
Laura M. De Santis
Netherlands Institute for Neuroscience NIN - KNAW
Paul Neering
Netherlands Institute for Neuroscience NIN - KNAW
Christian Boehler
University of Freiburg
Kirti Sharma
University of Freiburg
Arno Aarts
ATLAS Neuroengineering
Tobias Holzhammer
ATLAS Neuroengineering
Rik J.J. van Daal
ATLAS Neuroengineering
Patrick Ruther
University of Freiburg
Maria Asplund
University of Freiburg
Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems
Roxana N. Kooijmans
Netherlands Institute for Neuroscience NIN - KNAW
Jülich Research Centre
Pieter R. Roelfsema
Netherlands Institute for Neuroscience NIN - KNAW
Pierre and Marie Curie University (UPMC)
Vrije Universiteit Amsterdam
University of Amsterdam
Advanced Science
2198-3844 (ISSN) 21983844 (eISSN)
Vol. In PressNeural Active Visual Prosthetics for Restoring Function (NeuraViPeR)
European Commission (EC) (EC/H2020/899287), 2023-06-01 -- 2025-02-28.
Subject Categories (SSIF 2025)
Neurosciences
DOI
10.1002/advs.202600028
PubMed
41984513
Related datasets
Supporting files [dataset]
URI: https://advanced.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2Fadvs.202600028&file=advs75276-sup-0001-SuppMat.docx