Polyimide based neural implants with stiffness improvement<br />KeekeunLee, et al.<br />António Filipe Sousa<br />Nº64427 ...
Neural implants <br />A novel structure for chronically implantable cortical electrodes using polyimide bio-polimer. These...
Objectives<br />• Stiffnessrequired for penetrating into the brain tissue<br />Hybrid device<br />• Flexibilityto accommod...
Electrode Design and Fabrication<br />• Siliconbackbonelayer, fromsilicon-oninsulatorsubstrate, isattached to thetipandcon...
1 – Fabrication starts with a 4 in. silicon-on insulator (SOI) substrate with varying device silicon thickness from 2 to 1...
5 – The top polyimide layer was spun, exposed, and developed to encapsulate or reveal the desired conducting surfaces (Fig...
Results<br />Fig. - The fabricated device was visualized through optical microscopy and scanning electron microscopy (SEM)...
More studies<br />Patric J. Rousche, et al.<br />Bioactive species such as NGF (neuronal growth factor) can be selectively...
Concluding<br />“We have demonstrated that our electrode design with a silicon backbone layer of 5–10 um is robust enough ...
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Polyimide based neural implants with stiffness improvement

A novel structure for chronically implantable cortical electrodes using polyimide bio-polimer. These devices have been designed to provide a conformal coverage when placed upon the curved surface of the brain.
Published on: Mar 4, 2016
Published in: Technology      
Source: www.slideshare.net


Transcripts - Polyimide based neural implants with stiffness improvement

  • 1. Polyimide based neural implants with stiffness improvement<br />KeekeunLee, et al.<br />António Filipe Sousa<br />Nº64427 MBioNano<br />
  • 2. Neural implants <br />A novel structure for chronically implantable cortical electrodes using polyimide bio-polimer. These devices have been designed to provide a conformal coverage when placed upon the curved surface of the brain. <br />The polyimide surface chemistry is amenable to modifications and preparations which allow a host of bioactive organic species to be either adsorbed or covalently bonded to its surface.<br />This type of polymer based intracortical neural implants present several attractive features: flexible, biocompatible and easily manufactured using existing microfabrication technology.<br />
  • 3. Objectives<br />• Stiffnessrequired for penetrating into the brain tissue<br />Hybrid device<br />• Flexibilityto accommodate micromotion<br />chronic implant <br />Neuroprosthetic applications <br />This paper describes the design, fabrication, and initial performance feasibility studies of the latest prototype polyimide-based intracortical implant.<br />
  • 4. Electrode Design and Fabrication<br />• Siliconbackbonelayer, fromsilicon-oninsulatorsubstrate, isattached to thetipandconnectorregionsoftheelectrode to increasestiffness<br />• Therecording sites are interfaced to theexternalcircuit via a 15-channel connector, wichisespeciallydesigned to facilitateprocessingof neural signals.<br />Fig. – SimpleSchematicdiagramofthe PI based neural implant<br />
  • 5. 1 – Fabrication starts with a 4 in. silicon-on insulator (SOI) substrate with varying device silicon thickness from 2 to 10μm and buried oxide thickness of 1 μm.<br />2 – Top device silicon layer was selectively etched away for flexible region using a 2000Å thick gold masking layer (Fig. a)<br />3 – The first layer of polyimide was spin-coated, exposed, and then developed as shown in Fig. b.<br />4 – A reactive ion etch (RIE) was used to clean and microroughen the polyimide surface prior to depositing the metal layers. After RIE, a 2000Å thick gold layer was deposited for recording sites, followed by wet etching (Fig. c).<br />
  • 6. 5 – The top polyimide layer was spun, exposed, and developed to encapsulate or reveal the desired conducting surfaces (Fig. d).<br />6 – Backside silicon etching was performed for 10 h in RIE with SF6. Clean and uniform silicon backside etching was obtained (Fig. e).<br />7 – After complete removal of backside silicon, the buried SiO2 was etched away in 49% HF acid solution (Fig. f).<br />8 – Several rinses with de-ionized water were performed to remove any unwanted etchant products.<br />
  • 7. Results<br />Fig. - The fabricated device was visualized through optical microscopy and scanning electron microscopy (SEM). The device has tri-shanks with five recording sites (20μm × 20 μ m). The stiff segment has a silicon backbone layer that is 1.5mm in length and 0.2mm in width for implantation intoratbrain.<br />Electrical Impedance<br />Saline tests were performed by immersing the shafts and connecting cable of the devices into a 0.9% saline solution at room temperature in a holding chamber sealed from room air.<br />
  • 8. More studies<br />Patric J. Rousche, et al.<br />Bioactive species such as NGF (neuronal growth factor) can be selectively pipetted into the via to provide neural in-growth toward the local electrode site region.<br />
  • 9. Concluding<br />“We have demonstrated that our electrode design with a silicon backbone layer of 5–10 um is robust enough to penetrate the rat’s pia without buckling.” KeekeunLee, et al.<br />“…thereiscontinuingevidence that a neural interface providing reliable and stable long-term implant function could be used for the realization of clinically useful cortical prostheses for the blind…”.<br />Patrick J. Rousche, et al.<br />

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