Multiwalled Carbon‐Nanotube‐Functionalized Microelectrode Arrays Fabricated by Microcontact Printing: Platform for Studying Chemical and Electrical Neuronal Signaling

Abstract

A facile method is proposed for the deposition of multiwalled carbon nanotube (MWCNT) layers onto microelectrode arrays by means of a microcontact printing technique, leading to the fabrication of MEAs characterized by well defined electrical and morphological properties. Using polydimethyl siloxane stamps, produced from different mold designs, a flexibility of printing is achieved that provides access to microscale, nanostructured electrodes. The thickness of MWCNT layers can be exactly predetermined by evaluating the concentration of the MWCNT solution employed in the process. The electrode morphology is further characterized using laser scanning and scanning electron microscopy. Next, by means of impedance spectroscopy analysis, the MWCNT-electrode contact resistance and MWCNT film resistance is measured, while electrochemical impedance spectroscopy is used to estimate the obtained electrode-electrolyte interface. Structural and electrochemical properties make these electrodes suitable for electrical stimulation and recording of neurons and electrochemical detection of dopamine. MWCNT-functionalized electrodes show the ability to detect micromolar amounts of dopamine with a sensitivity of 19 nA μm(-1) . In combination with their biosensing properties, preliminary electrophysiological measurements show that MWCNT microelectrodes have recording properties superior to those of commercial TiN microelectrodes when detecting neuronal electrical activity under long-term cell-culture conditions. MWCNT-functionalized microelectrode arrays fabricated by microcontact printing represent a versatile and multipurpose platform for cell-culture monitoring.

A Review of Organic and Inorganic Biomaterials for Neural Interfaces

“…[29] In another study, Prato and co-workers used the micro-contact printing technique to deposit functionalized MWCNTs onto arrays of titanium nitride (TiN), creating CNT microelectrode arrays with well-defined electrical and morphological properties. [291] To accomplish this task, polydimethylsiloxane (PDMS) stamps produced from microfabricated molds were used to transfer MWCNT films (Figure 11g and 11h). They showed that functionalized MWCNT microelectrodes exhibit electrochemical and structural properties favorable for both neural recording and electrochemical detection of neurotransmitters, such as dopamine.…”

“…In addition, electrophysiological measurements from cultured hippocampal neurons showed that MWCNT microelectrodes had recording properties superior to those of commercial TiN microelectrodes under long-term cell-culture conditions (Figure 11i–k). [291] …”

Carbon-based smart nanomaterials in biomedicine and neuroengineering

“…Deposition of CNTs onto TiN microelectrode arrays was proposed by means of a micro-contact printing technique by Fuchsberger and colleagues [114], and showed superior recording properties compared to commercial TiN microelectrodes. The same microelectrodes were also employed to electrically stimulate and record neuronal activity, as well as to detect low concentrated amounts of dopamine.…”

Synthesis, Properties, and Biological Application of Perfect Crystal Gold Nanowires: A Review

“…Although there have been continuous efforts to increase the spatial resolution of neural recording by reducing the size of the conventional electrodes, it is difficult to avoid the deterioration of their mechanical strength and electrical conductivity, which are important for implanting the electrode and collecting neural signal, respectively. Recently, nanomaterials such as carbon nanotubes, silicon nanowires, or gold nanoparticles were employed to fabricate neural electrodes, allowing the successful miniaturization of the electrode without sacrificing material properties [15,[51][52][53][54][55][56][57][58][59][60][61] . Single-crystalline Au NWs possessing superflexibility as well as superstrength, high electrical conductivity, and well-defined geometry with sharp tip can potentially be ideal neural electrode materials.…”