Silicon Carbide Materials for Biomedical Applications

Frewin, Christopher L.; Coletti, Camilla; Register, Joseph; Nezafati, Maysam; Thomas, Sylvia; Saddow, Stephen E.

doi:10.1007/978-3-319-08648-4_7

Cited by 11 publications

(9 citation statements)

References 156 publications

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“…Our group believes an alternative material strategy may address both issues simultaneously. The device would be constructed exclusively of one material which has a demonstrated track record of physical robustness, chemical inertness, and a great degree of biological tolerance: crystalline silicon carbide (SiC) [ 25 , 26 , 27 , 28 , 29 , 30 , 31 ]. Additionally, the amorphous form of SiC ( a -SiC) has also been demonstrated as an effective insulating coating which does not take up water and is very compatible with neural cells [ 25 , 32 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

Demonstration of a Robust All-Silicon-Carbide Intracortical Neural Interface

Bernardin

Frewin²,

Everly³

et al. 2018

Micromachines

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Intracortical neural interfaces (INI) have made impressive progress in recent years but still display questionable long-term reliability. Here, we report on the development and characterization of highly resilient monolithic silicon carbide (SiC) neural devices. SiC is a physically robust, biocompatible, and chemically inert semiconductor. The device support was micromachined from p-type SiC with conductors created from n-type SiC, simultaneously providing electrical isolation through the resulting p-n junction. Electrodes possessed geometric surface area (GSA) varying from 496 to 500 K μm2. Electrical characterization showed high-performance p-n diode behavior, with typical turn-on voltages of ~2.3 V and reverse bias leakage below 1 nArms. Current leakage between adjacent electrodes was ~7.5 nArms over a voltage range of −50 V to 50 V. The devices interacted electrochemically with a purely capacitive relationship at frequencies less than 10 kHz. Electrode impedance ranged from 675 ± 130 kΩ (GSA = 496 µm2) to 46.5 ± 4.80 kΩ (GSA = 500 K µm2). Since the all-SiC devices rely on the integration of only robust and highly compatible SiC material, they offer a promising solution to probe delamination and biological rejection associated with the use of multiple materials used in many current INI devices.

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Section: Introductionmentioning

confidence: 99%

Demonstration of a Robust All-Silicon-Carbide Intracortical Neural Interface

Bernardin

Frewin²,

Everly³

et al. 2018

Micromachines

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“…With traditional silicon probes, reducing size increases the occurrence of probe fracture at high stress regions [57]. SiC is a much more robust material, with a reduced tendency to fracture at these desired smaller sizes, while maintaining the mechanical strength needed for proper penetration of neural tissue [24,27]. Therefore, SiC is an excellent material for developing a high electrode density neural interface, allowing for further reduction in size while greatly minimizing risk of fracture.…”

Section: Discussionmentioning

confidence: 99%

“…It has also demonstrated a high degree of biological tolerance in vitro [21,22,23,24]. In addition, amorphous SiC ( a -SiC), which provides excellent electrical insulation, has also shown good compatibility with neural cells [24,25,26] and has previously been used in the fabrication of several types of MEAs [27,28,29,30,31,32]. The properties of crystalline and amorphous SiC, and the results of previous studies, indicate that SiC can address the interrelated issues of INI biocompatibility and long-term reliability.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of a Monolithic Implantable Neural Interface from Cubic Silicon Carbide

et al. 2019

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One of the main issues with micron-sized intracortical neural interfaces (INIs) is their long-term reliability, with one major factor stemming from the material failure caused by the heterogeneous integration of multiple materials used to realize the implant. Single crystalline cubic silicon carbide (3C-SiC) is a semiconductor material that has been long recognized for its mechanical robustness and chemical inertness. It has the benefit of demonstrated biocompatibility, which makes it a promising candidate for chronically-stable, implantable INIs. Here, we report on the fabrication and initial electrochemical characterization of a nearly monolithic, Michigan-style 3C-SiC microelectrode array (MEA) probe. The probe consists of a single 5 mm-long shank with 16 electrode sites. An ~8 µm-thick p-type 3C-SiC epilayer was grown on a silicon-on-insulator (SOI) wafer, which was followed by a ~2 µm-thick epilayer of heavily n-type (n+) 3C-SiC in order to form conductive traces and the electrode sites. Diodes formed between the p and n+ layers provided substrate isolation between the channels. A thin layer of amorphous silicon carbide (a-SiC) was deposited via plasma-enhanced chemical vapor deposition (PECVD) to insulate the surface of the probe from the external environment. Forming the probes on a SOI wafer supported the ease of probe removal from the handle wafer by simple immersion in HF, thus aiding in the manufacturability of the probes. Free-standing probes and planar single-ended test microelectrodes were fabricated from the same 3C-SiC epiwafers. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed on test microelectrodes with an area of 491 µm2 in phosphate buffered saline (PBS) solution. The measurements showed an impedance magnitude of 165 kΩ ± 14.7 kΩ (mean ± standard deviation) at 1 kHz, anodic charge storage capacity (CSC) of 15.4 ± 1.46 mC/cm2, and a cathodic CSC of 15.2 ± 1.03 mC/cm2. Current-voltage tests were conducted to characterize the p-n diode, n-p-n junction isolation, and leakage currents. The turn-on voltage was determined to be on the order of ~1.4 V and the leakage current was less than 8 μArms. This all-SiC neural probe realizes nearly monolithic integration of device components to provide a likely neurocompatible INI that should mitigate long-term reliability issues associated with chronic implantation.

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“…We performed 5 tests with 2 samples of each material in each test with a final N = 10. Representative fluorescent micrographs are shown in Figure 1 (details of these in vitro experiments can be found in [37]. From extensive in vitro observations (see typical results in Fig.…”

Section: C-sic In Vitro Biocompatibilitymentioning

confidence: 98%

3C-SiC on Si: A Versatile Material for Electronic, Biomedical and Clean Energy Applications

Frewin

Reyes

et al. 2014

MRS Proc.

Self Cite

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Silicon carbide (SiC) has long been known as a robust semiconductor with superior properties to silicon for electronic applications. Consequently a tremendous amount of international activity has been on-going for over four decades to develop high-power solid state SiC electronics. While this activity has focused on the hexagonal polytypes of SiC, the only form that can be grown directly on Si substrates, 3C-SiC (or cubic SiC), has been researched for non-electronic applications such as MEMS and biosensors. In particular in our group we have pioneered several biomedical devices using 3C-SiC grown on Si substrates, and recently have been investigating the use of this novel material for clean energy applications. This paper first reviews progress made in the area of 3C-SiC electronic devices. Next a review of nearly a decade of biomedical activity is presented, with particular emphasis on the most promising applications: in vivo glucose monitoring, biomedical implants for connecting the human nervous system to advanced prosthetics, and MEMS/NEMS research aimed at allowing for in vivo diagnostic and therapeutic systems for advanced biomedical applications. Recent published work in the area of hydrogen production via electrolysis using 3C-SiC closes the paper as this last application is extremely promising for the burgeoning hydrogen economy and demonstrates a third important application of 3C-SiC on Si -its potential use in clean energy systems.

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Silicon Carbide Materials for Biomedical Applications

Cited by 11 publications

References 156 publications

Demonstration of a Robust All-Silicon-Carbide Intracortical Neural Interface

Demonstration of a Robust All-Silicon-Carbide Intracortical Neural Interface

Fabrication of a Monolithic Implantable Neural Interface from Cubic Silicon Carbide

3C-SiC on Si: A Versatile Material for Electronic, Biomedical and Clean Energy Applications

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