The Safety of Micro-Implants for the Brain

Abstract

Technological advancements in electronics and micromachining now allow the development of discrete wireless brain implantable micro-devices. Applications of such devices include stimulation or sensing and could enable direct placement near regions of interest within the brain without the need for electrode leads or separate battery compartments that are at increased risk of breakage and infection. Clinical use of leadless brain implants is accompanied by novel risks, such as migration of the implant. Additionally, the encapsulation material of the implants plays an important role in mitigating unwanted tissue reactions. These risks have the potential to cause harm or reduce the service of life of the implant. In the present study, we have assessed post-implantation tissue reaction and migration of borosilicate glass-encapsulated micro-implants within the cortex of the brain. Twenty borosilicate glass-encapsulated devices (2 × 3.5 × 20 mm) were implanted into the parenchyma of 10 sheep for 6 months. Radiographs were taken directly post-surgery and at 3 and 6 months. Subsequently, sheep were euthanized, and GFAP and IBA-1 histological analysis was performed. The migration of the implants was tracked by reference to two stainless steel screws placed in the skull. We found no significant difference in fluoroscopy intensity of GFAP and a small difference in IBA-1 between implanted tissue and control. There was no glial scar formation found at the site of the implant’s track wall. Furthermore, we observed movement of up to 4.6 mm in a subset of implants in the first 3 months of implantation and no movement in any implant during the 3–6-month period of implantation. Subsequent histological analysis revealed no evidence of a migration track or tissue damage. We conclude that the implantation of this discrete micro-implant within the brain does not present additional risk due to migration.

Comparative analysis of energy transfer mechanisms for neural implants

“…Designing energy sources for such small scales without sacrificing functionality is challenging. Implants must be hermetically sealed and have a regulated density; for instance, one study achieved a density about twice that of brain tissue without adverse tissue reactions or migration ( Dabbour et al, 2021 ). No adverse tissue reactions or migration tracks were observed in the study, suggesting effective biocompatibility.…”

A perspective on electroencephalography sensors for brain-computer interfaces

“…The considerable risks related to the surgery for implant application, added to the post-surgery risks, including potential implant rejection, biofouling and implant migration [30] have so far strongly limited deployment of institute of electrical and electronic engineers (IEEE) BCIs to neuroscience research and potentially to severely impaired individuals. Alongside ITR limitations [31], the long-term performance and biocompatibility of implanted devices remains one of the most critical challenges for iEEG-based BCIs, where biocompatibility needs to guarantee the absence of any type harmful interactions between the body tissue/fluid with the sensor and viceversa [22].…”

The future is here: Mind control and torture in the digital era

“…Neural implants have multiple applications in medicine, especially related to neurostimulation in motor and sensory disorders, but also epilepsy, and they are in early experimentation stage in depressive and obsessive-compulsive disorders (Costa e Silva & Steffen, 2017). This is a rapidly progressing research area in which biochips and implants are built in new and better materials that produce no tissue rejection, incorporating nanotechnologies to diminish the size and with more powerful software to control and interact with the neural system (Dabbour et al, 2021;Salari et al, 2022;Wan et al, 2021) while, again, there is no international regulation of its use (McGee & Maguire, 2007). The most important concern regarding the use of neuroimplants -not in the near future, for now -is represented by the possibility of controlling an individual's mental functions via wireless waves interacting with the electric activity of the brain.…”