Abstract:Chronically implanted neural probes are powerful tools to decode brain activity however, recording population and spiking activity over long periods remains a major challenge. Here, we designed and fabricated flexible intracortical Michigan-style arrays with a shank cross-section per electrode of 250 μm$$^2$$
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utilizing the polymer paryleneC with the goal to improve the immune acceptance. As flexible neural probes … Show more
“…According to Formula (1), the bending stiffness of the 1 μm-thick device is 2.6 × 10 −14 N m 2 , which is smaller than most polymer implants summarized in Fig. 4d and Table S2 and close to the bending stiffness of axons 14 , 16 , 17 , 31 – 37 . Fig.…”
Section: Resultsmentioning
confidence: 82%
“…In recent years, flexible BCI devices made from polymers with a smaller cross-section and bending stiffness have been manifested to be more compliant with biological tissue to reduce relative shear motion, suppress the neuroinflammatory response and improve the tissue–electrode interface 12 , 13 . Srikantharajah et al proposed a minimally‑invasive flexible intracortical probe with a 250 μm 2 cross-section per electrode, which improves the immune acceptance of the implants 14 . Musk et al invented flexible polyimide neural threads that can be efficiently implanted into the brain by a robotic machine 15 .…”
Implantable brain–computer interface (BCI) devices are an effective tool to decipher fundamental brain mechanisms and treat neural diseases. However, traditional neural implants with rigid or bulky cross-sections cause trauma and decrease the quality of the neuronal signal. Here, we propose a MEMS-fabricated flexible interface device for BCI applications. The microdevice with a thin film substrate can be readily reduced to submicron scale for low-invasive implantation. An elaborate silicon shuttle with an improved structure is designed to reliably implant the flexible device into brain tissue. The flexible substrate is temporarily bonded to the silicon shuttle by polyethylene glycol. On the flexible substrate, eight electrodes with different diameters are distributed evenly for local field potential and neural spike recording, both of which are modified by Pt-black to enhance the charge storage capacity and reduce the impedance. The mechanical and electrochemical characteristics of this interface were investigated in vitro. In vivo, the small cross-section of the device promises reduced trauma, and the neuronal signals can still be recorded one month after implantation, demonstrating the promise of this kind of flexible BCI device as a low-invasive tool for brain–computer communication.
“…According to Formula (1), the bending stiffness of the 1 μm-thick device is 2.6 × 10 −14 N m 2 , which is smaller than most polymer implants summarized in Fig. 4d and Table S2 and close to the bending stiffness of axons 14 , 16 , 17 , 31 – 37 . Fig.…”
Section: Resultsmentioning
confidence: 82%
“…In recent years, flexible BCI devices made from polymers with a smaller cross-section and bending stiffness have been manifested to be more compliant with biological tissue to reduce relative shear motion, suppress the neuroinflammatory response and improve the tissue–electrode interface 12 , 13 . Srikantharajah et al proposed a minimally‑invasive flexible intracortical probe with a 250 μm 2 cross-section per electrode, which improves the immune acceptance of the implants 14 . Musk et al invented flexible polyimide neural threads that can be efficiently implanted into the brain by a robotic machine 15 .…”
Implantable brain–computer interface (BCI) devices are an effective tool to decipher fundamental brain mechanisms and treat neural diseases. However, traditional neural implants with rigid or bulky cross-sections cause trauma and decrease the quality of the neuronal signal. Here, we propose a MEMS-fabricated flexible interface device for BCI applications. The microdevice with a thin film substrate can be readily reduced to submicron scale for low-invasive implantation. An elaborate silicon shuttle with an improved structure is designed to reliably implant the flexible device into brain tissue. The flexible substrate is temporarily bonded to the silicon shuttle by polyethylene glycol. On the flexible substrate, eight electrodes with different diameters are distributed evenly for local field potential and neural spike recording, both of which are modified by Pt-black to enhance the charge storage capacity and reduce the impedance. The mechanical and electrochemical characteristics of this interface were investigated in vitro. In vivo, the small cross-section of the device promises reduced trauma, and the neuronal signals can still be recorded one month after implantation, demonstrating the promise of this kind of flexible BCI device as a low-invasive tool for brain–computer communication.
“…However, it has been challenging to adopt a multi-site architecture with soft probes since they require multiple shuttles for delivery. Recently [26] and [28] demonstrated a shuttle-free method of delivering a multi-shank flexible probes by temporary stiffening them with PEG coating. As there is no additional shuttle involved, it creates a minimal footprint during implantation.…”
Section: Discussionmentioning
confidence: 99%
“…have been employed to temporarily enhance the stiffness of soft probes [12] . Barring a few exceptions [26][27][28] , these methods are mostly limited to probes confined to a single location (single shank) and hence, have a narrower scope of application. Recently multi-shank probes made from parylene C were implanted by temporary stiffening the shanks with PEG while leaving the tips exposed [26,27] .…”
Section: Introductionmentioning
confidence: 99%
“…Barring a few exceptions [26][27][28] , these methods are mostly limited to probes confined to a single location (single shank) and hence, have a narrower scope of application. Recently multi-shank probes made from parylene C were implanted by temporary stiffening the shanks with PEG while leaving the tips exposed [26,27] . These probes combine the virtues of a multi-site architecture and small footprint, but the implantation strategy is unsuitable for different probe geometries.…”
Silicon probes have played a key role in studying the brain. However, the stark mechanical mismatch between these probes and the brain leads to chronic damage in the surrounding neural tissue, limiting their application in research and clinical translation. Mechanically flexible probes made of thin plastic shanks offer an attractive tissue-compatible alternative but are difficult to implant into the brain and struggle to achieve the electrode density and layout necessary for the high-resolution applications their silicon counterparts excel at. Here, we present a multi-shank high-density flexible neural probe design which emulates the functionality of stiff silicon arrays for neural population recordings across multiple sites within a given region. The flexible probe is accompanied by a detachable 3D printed implanter which delivers the probe by means of hydrophobic-coated shuttles. The shuttles can then be retracted with minimal movement, and the implanter houses the electronics necessary for in vivo recording applications. Validation of the probes through extracellular recordings from multiple brain regions and histological evidence of minimal foreign body response opens the path to long-term chronic monitoring of neural ensembles.
Neurologic and neuropsychiatric disorders substantially impact the pediatric population, but there is a lack of dedicated devices for monitoring the developing brain in animal models, leading to gaps in mechanistic understanding of how brain functions emerge and their disruption in disease states. Due to the small size, fragility, and high‐water content of immature neural tissue, as well as the absence of a hardened skull to mechanically support rigid devices, conventional neural interface devices are poorly suited to acquire brain signals without inducing damage. Here, we design conformable, implantable, conducting polymer‐based probes (NeuroShanks) for precise targeting in the developing mouse brain without the need for skull‐attached, rigid mechanical support structures. These probes enabled acquisition of high spatiotemporal resolution neurophysiologic activity from superficial and deep brain regions across unanesthetized behavioral states without causing tissue disruption or device failure. Once implanted, probes were mechanically stable and permitted precise, stable signal monitoring at the level of the local field potential and individual action potentials. These results support the translational potential of such devices for clinically indicated neurophysiologic recording in pediatric patients. Additionally, we reveal the role of organic bioelectronics as an enabling technology to address questions in developmental neuroscience.This article is protected by copyright. All rights reserved
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