Processing of platinum electrodes for parylene-C based neural probes

Ong, Xiao Chuan; Forssell, Mats; Fedder, Gary K.

doi:10.1109/memsys.2016.7421673

Cited by 5 publications

(3 citation statements)

References 12 publications

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“…However, no long-term chronic recording data was provided to conclude any direct relationship between the use of polyimide to chronic reliability [ 63 ]. In fact, over the past decade, neural probes based on a vast number of soft materials such as parylene-C [ 30 , 34 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 123 ], polycarbonate [ 27 ], SU-8 [ 2 ], and benzocyclobutene (BCB) [ 124 ] have been reported. However, only a few of these works demonstrated the long-term neural recording ( Table 4 ).…”

Section: Strategies To Achieve Chronic Reliabilitymentioning

confidence: 99%

“…Lastly, a considerable amount of work has been dedicated to optimizing the electrode-tissue interface to minimize the foreign body reaction. With rapid advancement of soft lithography and interdisciplinary research between engineering, material science and neuroscience, the materials such as biocompatible coatings [ 31 , 32 , 33 ], bioactive coatings [ 20 , 21 , 22 , 23 , 31 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ], and flexible substrate materials (e.g., polyimide [ 41 , 42 , 43 , 44 ], parylene-C [ 30 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ], SU-8 [ 52 ], polycarbonate [ 27 ], silk [ 35 ], and fibers [ 27 ], carbon nanotube (CNT) [ 53 ], and polyvinyl acetate [ 54 ]), have been explored. (Note that the term ‘biocompatible’ is used to imply a characteristic of a material that exhibits good biocompatibility in the central nervous system (CNS) [ 55 ].)…”

Section: Introductionmentioning

confidence: 99%

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Neural Probes for Chronic Applications

Kook

Lee

et al. 2016

Micromachines

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Developed over approximately half a century, neural probe technology is now a mature technology in terms of its fabrication technology and serves as a practical alternative to the traditional microwires for extracellular recording. Through extensive exploration of fabrication methods, structural shapes, materials, and stimulation functionalities, neural probes are now denser, more functional and reliable. Thus, applications of neural probes are not limited to extracellular recording, brain-machine interface, and deep brain stimulation, but also include a wide range of new applications such as brain mapping, restoration of neuronal functions, and investigation of brain disorders. However, the biggest limitation of the current neural probe technology is chronic reliability; neural probes that record with high fidelity in acute settings often fail to function reliably in chronic settings. While chronic viability is imperative for both clinical uses and animal experiments, achieving one is a major technological challenge due to the chronic foreign body response to the implant. Thus, this review aims to outline the factors that potentially affect chronic recording in chronological order of implantation, summarize the methods proposed to minimize each factor, and provide a performance comparison of the neural probes developed for chronic applications.

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Section: Strategies To Achieve Chronic Reliabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Neural Probes for Chronic Applications

Kook

Lee

et al. 2016

Micromachines

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“…A 1 min Ar + mill is performed to remove PtO 2 formed on the electrodes during the etching of paryleneC using O 2 RIE. The presence of the PtO 2 is detrimental to electrode perfor mance [24]. The dice are then heated to 300 °C in a custom built vacuum heater with a flow of N 2 to achieve a pressure of 10 mT in order to improve the encapsulation properties of paryleneC [14].…”

Section: Fabrication Of Parylene-c Probes On Si Substratementioning

confidence: 99%

A transfer process to fabricate ultra-compliant neural probes in dissolvable needles

Ong

Khilwani

Forssell

et al. 2017

J. Micromech. Microeng.

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A fabrication approach for ultra-miniature ultra-compliant neural probes with parylene-C insulation that are embedded in biodissolvable insertion needles was previously established by the authors. However, that approach required application of a peeling process to release the probe-needle assembly from its handle wafer. The use of thermal annealing in vacuum to improve encapsulation properties of parylene-C results in increased adhesion to the substrate that undermines the peeling process. In this paper, we introduce a transfer process step that eliminates the peeling process and allows the potential use of a wide range of sacrificial release materials. The transfer step increases the versatility of the overall fabrication approach since it allows the integration of insertion needle and sacrificial release materials that otherwise would not have been compatible with the high-temperature annealing. Several sacrificial release materials, including photoresist, polydimethylsiloxane, mounting adhesive, and liquid wax, are investigated and characterized for suitability in the transfer process. Considering compatibility with the biodissolvable needle attachment, a liquid wax is identified to be an effective material because of its strong adhesion to relevant surfaces, its ability to be spin coated, and its dissolvability in isopropyl alcohol.

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A silicon neural probe fabricated using DRIE on bonded thin silicon

Ong

Willard

Forssell

et al. 2016

2016 38th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

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A silicon neural probe fabricated using a deep reactive ion etching based process on 250 μm thin silicon wafers was developed. The fabricated probes replicate the design of soft parylene-C based probes embedded in dissolvable needles and can therefore also be used to test the encapsulation properties of parylene-C in-vivo without introducing additional effects introduced by the dissolvable gel. The process also demonstrates the possibility of performing conventional photolithography on substrates bonded to a handle wafer using a backgrinding liquid wax (BGL7080) as an adhesive. This technique would allow integration of Si wafer thinning into the fabrication of neural probes, potentially allowing a range of neural probes of different thicknesses to be fabricated. Fabricated probes were characterized using electrochemical impedance spectroscopy (EIS) yielding a measured impedance value of ~80 kΩ at 1 kHz for 15 μm by 115 μm platinum electrodes, indicating that extracellular neural recordings are possible. The neural probes were inserted into the substantia nigra of a mouse that showed successful recording of neural activity. Probes fabricated using this technique can thus be potentially used in the study of Parkinson's disease.

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Processing of platinum electrodes for parylene-C based neural probes

Cited by 5 publications

References 12 publications

Neural Probes for Chronic Applications

Neural Probes for Chronic Applications

A transfer process to fabricate ultra-compliant neural probes in dissolvable needles

A silicon neural probe fabricated using DRIE on bonded thin silicon

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