Electrochemical layer-by-layer approach to fabricate mechanically stable platinum black microelectrodes using a mussel-inspired polydopamine adhesive.
OBJECTIVE
Platinum black (PtBK) has long been used for microelectrode fabrication owing to its high recording performance of neural signals. The porous structure of PtBK enlarges the surface area and lowers the impedance, which results in background noise reduction. However, the brittleness of PtBK has been a problem in practice. In this work, we report mechanically stable PtBK microelectrodes using a bioinspired adhesive film, polydopamine (pDA), while maintaining the low impedance of PtBK.


METHODS
The pDA layer was incorporated into the PtBK structure through electrochemical layer-by-layer deposition. Varying the number of layers and the order of materials, multi-layered pDA-PtBK hybrids were fabricated and the electrical properties, both impedance and charge injection limit, were evaluated.


RESULTS
Multilayered pDA-PtBK hybrids had electrical impedances as low as PtBK controls and charge injection limit twice larger than controls. For the 30 min-ultrasonication agitation test, impedance levels rarely changed for some of the pDA-PtBK hybrids indicating that the pDA improved the mechanical property of the PtBK structures. The pDA-PtBK hybrid microelectrodes readily recorded neural signals of cultured hippocampal neurons, where background noise levels and signal-to-noise were 2.43 ∼ 3.23 μVrms and 28.4 ∼ 69.1, respectively.


CONCLUSIONS
The developed pDA-PtBK hybrid microelectrodes are expected to be applicable to neural sensors for neural prosthetic studies.
Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-338, Republic of Korea.
Raeyoung
R
Kim
Yoonkey
Y
Nam
D000200:Action Potentials / Q000502:physiology*; D000269:Adhesives / Q000737:chemistry*; D000818:Animals; D040761:Biomimetic Materials / Q000138:chemical synthesis; D049872:Bivalvia / Q000737:chemistry; D002478:Cells, Cultured; D017097:Electric Impedance; D004595:Electroplating / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006244:Hardness; D007211:Indoles / Q000737:chemistry*; D008422:Materials Testing; D008839:Microelectrodes; D009474:Neurons / Q000502:physiology*; D010984:Platinum / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D066330:Printing, Three-Dimensional; D051381:Rats; D017207:Rats, Sprague-Dawley; D013718:Tensile Strength
D000269:Adhesives; D007211:Indoles; D011108:Polymers; C568283:polydopamine; D010984:Platinum