1

DEMONSTRATION OF CORTICAL RECORDING AND REDUCED INFLAMMATORY RESPONSE USING FLEXIBLE POLYMER NEURAL PROBES

LIGA and Biophotonics Lab

André Mercanzini, Karen Cheung, Derek Buhl, Marc Boers, Anne Maillard, Philippe, Colin, Jean-Charles Bensadoun, Arnaud Bertsch, Alan Carleton and Philippe RenaudEcole Polytechnique Fédérale de Lausanne, EPFL, SwitzerlandUniversity of British Columbia, Vancouver, CanadaMassachusetts Institute of Technology, USA

NTHUInstitute of NanoEngineering and MicroSystem Speaker：Wen Cheng Yang

2

Outline

Introduction Device fabrication Device packaging Electrical characterization Acute recordings Histology Conclusion

LIGA and Biophotonics Lab

3

Outline

Introduction Device fabrication Device packaging Electrical characterization Acute recordings Histology Conclusion

4

Introduction

Neural interfaces currently help neuroscientists in their study of the brain’s functions and promise to introduce new solutions for conditions such as Parkinson’s and paralysis.

In order to decrease this response, flexible probes have been designed by several groups in order to comply with brain tissue motion.

Polyimide probes and parylene probes have been developed in order to decrease brain-device compliance mismatch.

5

Introduction

Ref： Leigh R. Hochberg, Mijail D. Serruya, Gerhard M. Friehs, Jon A. Mukand, Maryam Saleh,Abraham H. Caplan, Almut Branner, David Chen, Richard D. Penn & John P. Donoghue. “Neuronal ensemble control of prosthetic devices by a human with tetraplegia”. Nature Vol 442.13 July 2006

6

Outline

Introduction Device fabrication Device packaging Electrical characterization Acute recordings Histology Conclusion

LIGA and Biophotonics Lab

7

Device fabrication

LIGA and Biophotonics Lab

Step 1：A 500 nm TiW and a 1000 nm sacrificial aluminum layer are deposited on a silicon wafer.

Step 2：Polyimide is spun to a thickness of 15 µm

Step 3：Ti/Pt/Ti metal sandwich is deposited atthicknesses of 50nm/200nm/50nm respectively.

8

Device fabrication

LIGA and Biophotonics Lab

Step 4：A second polyimide layer is spun to a thickness of 2 µm

Step 5：A second polyimide Ti/Pt/Ti sandwich is then deposited and etched thus defining the second layer of electrodes. The finalpolyimide layer is spun to a thickness of 2um

9

Device fabrication

LIGA and Biophotonics Lab

Step 6：The three layers of polyimide are then etched in an O2 plasma using the Ti and sacrificial Al as etch stops. The oxide hard mask is dry etched and the wafer is ready for packaging and device release

10

Outline

LIGA and Biophotonics Lab

SEM image of the fabricated device.

11

Outline

Introduction Device fabrication Device packaging Electrical characterization Acute recordings Histology Conclusion

LIGA and Biophotonics Lab

12

Device packaging

LIGA and Biophotonics Lab

Microscope image demonstrating crossover of metal layers and electrode sites.

A packaged flexible neural probe device

13

Outline

Introduction Device fabrication Device packaging Electrical characterization Acute recordings Histology Conclusion

LIGA and Biophotonics Lab

14

Electrical characterization

LIGA and Biophotonics Lab

Impedance magnitude and phase for one electrode site

Figure shows the typical impedance spectrum of devices .There was no apparent difference in impedance between the bottom and top metal layers.

15

Outline

Introduction Device fabrication Device packaging Electrical characterization Acute recordings Histology Conclusion

16

Acute recordings

EEG recordings from 16 electrode sites distinguishing 2 single units

Demonstrates local field potential recordingsidentifying two single units in the mouse cortex. All 16 electrode sites were active.

17

Outline

Introduction Device fabrication Device packaging Electrical characterization Acute recordings Histology Conclusion

18

Histology

General staining for cells with DAPI Staining for microglia, CD11b (green) and astrocytes, GFAP (red).

19

Outline

Introduction Device fabrication Device packaging Electrical characterization Acute recordings Histology Conclusion

20

Conclusion

Due to the smaller neural probe size, and brain-probe compliance match, we have demonstrated reduced insertion and chronic damage using polyimide

microfabricated probes.

21

LIGA and Biophotonics Lab

Thanks for your attendance .