In vitro and in vivo characterization of SU-8 flexible neuroprobe: From mechanical properties to electrophysiological recording

Huang, Shun Ho; Lin, San‐Yih; Chen, Jia Jin Jason

doi:10.1016/j.sna.2014.06.005

Cited by 30 publications

(24 citation statements)

References 50 publications

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“…900 nm and widths of 20 μm. We have also used polyimide flexible thin-film probes with thicknesses, 25 μm, comparable to the lower end of the range, 20-100 μm used in reported studies (29,30,32,33); the width of these thin-film probes, 500 μm, was comparable to the outer diameter of the capillary needle that was used for injection of mesh electronics, ca. 650 μm.…”

Section: Resultsmentioning

confidence: 99%

“…These data further showed NF signals within the mesh electronics interior at all times, and that the interior NF signal is the same as baseline at 3 mo. The horizontal brain slices described above provide detailed information about the local tissue/probe interfaces for the mesh electronics and flexible thin-film implants and also allow comparison with previous studies of more rigid conventional probes (29,30,32,33). These horizontal sections cannot, however, provide a global view of the probe/tissue interface, which typically extends millimeters in depth in the mouse brain.…”

Section: Resultsmentioning

confidence: 99%

“…Specifically, the mesh has all size features comparable to or smaller than neuron soma and bending stiffness values of ∼0.1 nN·m, comparable to a 150-μm-thick brain tissue slice (i.e., the same as the overall implanted open mesh diameter), ∼0.4 nN·m (27,28) and orders of magnitude smaller (more flexible) than conventional probes (14,29,30). Herein, we present systematic time-dependent histology studies of the mesh electronics/brain-tissue interface obtained from tissue sections perpendicular (horizontal slices) and parallel (sagittal slices) to the long axis of probes, as well as time-dependent measurements obtained from horizontal tissue sections containing the cross-sections Significance Seamless integration of electrical probes within neural tissue could substantially enhance their impact and open up new opportunities in neuroscience research through electronic therapeutics.…”

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confidence: 99%

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Syringe-injectable mesh electronics integrate seamlessly with minimal chronic immune response in the brain

Zhou

Hong

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

193

211

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Implantation of electrical probes into the brain has been central to both neuroscience research and biomedical applications, although conventional probes induce gliosis in surrounding tissue. We recently reported ultraflexible open mesh electronics implanted into rodent brains by syringe injection that exhibit promising chronic tissue response and recording stability. Here we report time-dependent histology studies of the mesh electronics/brain-tissue interface obtained from sections perpendicular and parallel to probe long axis, as well as studies of conventional flexible thin-film probes. Confocal fluorescence microscopy images of the perpendicular and parallel brain slices containing mesh electronics showed that the distribution of astrocytes, microglia, and neurons became uniform from 2–12 wk, whereas flexible thin-film probes yield a marked accumulation of astrocytes and microglia and decrease of neurons for the same period. Quantitative analyses of 4- and 12-wk data showed that the signals for neurons, axons, astrocytes, and microglia are nearly the same from the mesh electronics surface to the baseline far from the probes, in contrast to flexible polymer probes, which show decreases in neuron and increases in astrocyte and microglia signals. Notably, images of sagittal brain slices containing nearly the entire mesh electronics probe showed that the tissue interface was uniform and neurons and neurofilaments penetrated through the mesh by 3 mo postimplantation. The minimal immune response and seamless interface with brain tissue postimplantation achieved by ultraflexible open mesh electronics probes provide substantial advantages and could enable a wide range of opportunities for in vivo chronic recording and modulation of brain activity in the future.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Syringe-injectable mesh electronics integrate seamlessly with minimal chronic immune response in the brain

Zhou

Hong

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

193

211

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“…Finally, the complete structure of the microelectrode arrays was released by the removal of the sacrificial layer, as depicted in Fig. 2(j) [9] [10]. The pattern of the microelectrode arrays were formed as depicted in Fig.…”

Section: Fabrication Process Of the Flexible Microelectrode Arraysmentioning

confidence: 99%

“…In some ways, such as chemical stability, high mechanical strength and flexibility, and high compatibility with polymeric packaging, SU-8 has more advantages than silicon [8]. The mechanical mismatch between soft tissue and silicon could lead to chronic inflammation at the implantation site, and then causing specific tissue fester because of the changes in the mechanical properties of the tissues [9]. To fabrication a flexible SU-8 based microelectrode arrays which can not only be soft to prevent chronic neurons damages of the surrounding area but also sustain resistance from culturing dorsal root ganglion (DRG) explants during surgical implantation.…”

Section: Introductionmentioning

confidence: 99%

A Flexible Microelectrode Array for Recording Signals of Culturing DRG Explants

Guan¹,

Chen²,

Li³

et al. 2016

dtetr

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Abstract. Owning to the advanced technology of microelectromechanical systems (MEMS), more and more precise microelectrode arrays are used to serve as neural prosthesis. Peripheral nerve injury and amputation have plagued neurosurgeons and patients. Neural interface have been served as a bridge between peripheral nerves and prosthetic limbs. In this study, to characterize the signals of culturing dorsal root ganglion (DRG) explants, a flexible electronic microelectrode arrays using SU-8 was designed to serve as neural interface to record neural signals of culturing DRG explants. The arrays are composed of thin gold electrode on a flexible material called SU-8, The materials and methods will play an important role in recording neural signals of culturing DRG explants. The goal of this study is to design an artificial limb that the amputees could control as if it was a natural extension of their own body.

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A Dual‐Layered Microfluidic System for Long‐Term Controlled In Situ Delivery of Multiple Anti‐Inflammatory Factors for Chronic Neural Applications

Frey

Bandaru

Zhang

et al. 2017

Adv Funct Materials

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We report the development of a microfluidic system capable of repeated infusions of antiinflammatory factors post-implantation for use as a coating for neural probes. This system consists of a microchannel in a thin gelatin methacryloyl (GelMA)-polyethylene glycol (PEG) composite hydrogel surrounded by a porous polydimethylsiloxane (PDMS) membrane, where the hydrogel can be dried to increase the stiffness for easy insertion. Reswelling allowed us to perfuse interleukin (IL)-4 and dexamethasone (DEX) as anti-inflammatory factors through the This article is protected by copyright. All rights reserved. 3 channel with minimal burst release and significant amounts of IL-4 were observed to release for up to 96 hr post-infusion. Repeated injections of IL-4 increased the ratio of prohealing M2 versus proinflammatory M1 phenotypes of macrophages encapsulated in the hydrogel by six fold compared with a single injection, over a 2-week period. These repeated infusions also significantly downregulated the expression of inflammatory markers tumor necrosis factor (TNF)-α and IL-6 in astrocytes encapsulated in hydrogel. To demonstrate the system as a coating of neural probe for in vivo applications, we further fabricated a prototype device, where a thin dual-layered microfluidic system was integrated onto a metal probe. Such a drug delivery system could help reduce the formation of a glial scar around neural probes.

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In vitro and in vivo characterization of SU-8 flexible neuroprobe: From mechanical properties to electrophysiological recording

Cited by 30 publications

References 50 publications

Syringe-injectable mesh electronics integrate seamlessly with minimal chronic immune response in the brain

Syringe-injectable mesh electronics integrate seamlessly with minimal chronic immune response in the brain

A Flexible Microelectrode Array for Recording Signals of Culturing DRG Explants

A Dual‐Layered Microfluidic System for Long‐Term Controlled In Situ Delivery of Multiple Anti‐Inflammatory Factors for Chronic Neural Applications

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