Ultrathin, dual-sided silicon neural microprobes realized using BCB bonding and aluminum sacrificial etching

Jeong

2019

Sensors

Microfabrication technology for cortical interfaces has advanced rapidly over the past few decades for electrophysiological studies and neuroprosthetic devices offering the precise recording and stimulation of neural activity in the cortex. While various cortical microelectrode arrays have been extensively and successfully demonstrated in animal and clinical studies, there remains room for further improvement of the probe structure, materials, and fabrication technology, particularly for high-fidelity recording in chronic implantation. A variety of non-conventional probes featuring unique characteristics in their designs, materials and fabrication methods have been proposed to address the limitations of the conventional standard shank-type (“Utah-” or “Michigan-” type) devices. Such non-conventional probes include multi-sided arrays to avoid shielding and increase recording volumes, mesh- or thread-like arrays for minimized glial scarring and immune response, tube-type or cylindrical probes for three-dimensional (3D) recording and multi-modality, folded arrays for high conformability and 3D recording, self-softening or self-deployable probes for minimized tissue damage and extensions of the recording sites beyond gliosis, nanostructured probes to reduce the immune response, and cone-shaped electrodes for promoting tissue ingrowth and long-term recording stability. Herein, the recent progress with reference to the many different types of non-conventional arrays is reviewed while highlighting the challenges to be addressed and the microfabrication techniques necessary to implement such features.

Section: Non-conventional Neural Probesmentioning

confidence: 99%

Section: Non-conventional Neural Probesmentioning

confidence: 99%

Section: Non-conventional Neural Probesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Recent Progress on Non-Conventional Microfabricated Probes for the Chronic Recording of Cortical Neural Activity

Jeong

2019

Sensors

“…With the development of neuroscience, especially brain science, novel microelectrode arrays are urgently needed by neuroscientists to further understand the working principles of the nervous system. On the one hand, the performances of MEMS microelectrode arrays have been improved in many aspects [ 33 ], e.g., three-dimensional arrays [ 34 ], dual-sided microelectrode arrays [ 35 , 36 ], microelectrode arrays with high-density stimulation/recording sites [ 37 ], integrated electronics or microfluidic channels [ 38 , 39 , 40 , 41 , 42 , 43 ], silicon probes for optogenetics or infrared stimulation probes [ 44 , 45 ]. On the other hand, according to different experimental requirements, some specially designed microelectrode arrays have been developed.…”

Section: Introductionmentioning

confidence: 99%

Design, Fabrication, Simulation and Characterization of a Novel Dual-Sided Microelectrode Array for Deep Brain Recording and Stimulation

Zhao

Gong

Huang

et al. 2016

Sensors

In this paper, a novel dual-sided microelectrode array is specially designed and fabricated for a rat Parkinson’s disease (PD) model to study the mechanisms of deep brain stimulation (DBS). The fabricated microelectrode array can stimulate the subthalamic nucleus and simultaneously record electrophysiological information from multiple nuclei of the basal ganglia system. The fabricated microelectrode array has a long shaft of 9 mm and each planar surface is equipped with three stimulating sites (diameter of 100 μm), seven electrophysiological recording sites (diameter of 20 μm) and four sites with diameter of 50 μm used for neurotransmitter measurements in future work. The performances of the fabricated microelectrode array were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. In addition, the stimulating effects of the fabricated microelectrode were evaluated by finite element modeling (FEM). Preliminary animal experiments demonstrated that the designed microelectrode arrays can record spontaneous discharge signals from the striatum, the subthalamic nucleus and the globus pallidus interna. The designed and fabricated microelectrode arrays provide a powerful research tool for studying the mechanisms of DBS in rat PD models.

Multimodal Neural Probes with Small Form Factor Based on Dual‐Side Fabrication

Adv Materials Technologies

Leong

et al. 2022

a specific region of the brain through various physical means, including electrical, chemical, optical, and acoustic, have been proposed to investigate neuronal circuits. [8][9][10][11][12] Furthermore, since neurons relay information to downstream neurons through either electrical or chemical synaptic transmission, real-time monitoring of neurotransmitters in the extracellular space of the brain offers additional insight to that observed from the electrophysiological activities. Thus, recently, multimodal neural probes that perform both electrical recording and neurotransmitter detection in the extracellular environment have also been proposed. [13][14][15] However, it is still a challenge to design a multimodal neural probe that detects both neurotransmitters and neural signals at a small form factor. For a multimodal neural probe, while a high-density neural recording and a high electrochemical sensitivity are preferred, a high channel count and sensitivity require a larger shank area. For example, the width of the probe scales linearly with the number of microelectrodes due to the signal lines. Similarly, for electrochemical detection, a larger working electrode (WE) on the shank is also required to achieve high sensitivity. Moreover, to achieve a reliable electrochemical analysis, two electrodes additional to the WE are required to form a three-electrode system. [16] However, because the shank dimension is directly related to the acute neural tissue damage during the insertion, it is important to design a shank with a small dimension. This clear trade-off between the probe dimension (i.e., tissue damage) and performance (i.e., channel counts and high sensitivity) is a major challenge in implementing a multimodal neural probe at a small form factor.To overcome this trade-off, several methods such as multilayer metal interconnect, [17] e-beam photolithography, [18] and dual-sided micropatterning [19,20] have been recently proposed to achieve high density without increasing the dimension of the polymer neural probes. Through these efforts, neural probe arrays with 16-channel SU-8, 32-channel polyimide (PI), and 64-channel Parylene-C (PC) shank have been reported using the standard monolithic microfabrication. [21][22][23][24] In the case of electrochemical analysis, a three-electrode system composed of working, reference, and counter electrodes (WE, RE, and CE) is often used. However, to prevent brain damage from the insertion of the third electrode, a two-electrode system is often Monitoring both individual neuronal spikes and neurotransmitters released from a specific brain region plays a significant role in understanding neuronal circuits and brain functionalities. While polymer neural probe offers distinctive advantages of flexibility, optical transparency, and biocompatibility, achieving high-density recording with multifunctionalities and multimodality is still a challenge due to limited microfabrication techniques. Here, a multimodal polymer neural probe array based on a dual-side fabrication process wit...