Chi660e potentiostat

Fabrication of the working electrode consisted of physically mixing 40 mg of prepared SAH with 5 mg of carbon black. Separately, polyvinylidene difluoride (PVDF) binder was dissolved in N, N-dimethylacetamide (99% pure) (DMAC) using a 1:10 ratio forming a gel-like consistency to transform the mixed carbon materials into a paste. Once the electrode paste was procured, it was transferred into the tip of a borosilicate capillary (outer diameter of 1.0 mm and inner diameter of 0.58 mm) resulting in a mass loading of 0.18 mg. The weight of the capillary was recorded before and after packing to obtain the mass of the electrode material added. The electrical contact was established by inserting a silver wire into the capillary.
The electrochemical performance of SAHs was tested using a three-electrode configuration via cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) techniques using CHI 660E potentiostat (CH Instruments, Austin, TX, USA) in 6 M KOH. The counter electrode was platinum, and the reference electrode was a saturated calomel electrode. Specific capacitance can be calculated as presented below, where C is the specific capacitance (F/g), I is the current density (A), $\Delta$ t is the discharge time, m is the mass of the active material in the working electrode (g), and $\Delta$ V is the potential (V) within the discharge time excluding the IR drop.
$$\mathrm{C}=\frac{I\times \Delta t}{m\times \Delta V}$$

The EC was tested by using a CHI 660E Potentiostat (CH Instruments Inc., China). For Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements, the electrochemical windows were controlled to be 0 − 1.5 V. EIS tests were performed in the frequency range of 10⁵ to 1 Hz at an amplitude of 5 mV and bias voltage of 0 V. CV tests of connected ECs in series or in parallel were carried out by using a Keithley 2450. For the AC-line filtering test, all the input AC signals were supplied by an arbitrary function generator (33511B, Agilent Technologies Inc., Tektronix, USA). For the AC line filtering test of connected ECs, the input signals were enlarged by an ATA-2041 high-voltage amplifier (Agitek, China). All the outputs were recorded by a RTB2002 mixed domain oscilloscope (Rohde & Schwarz, Germany). The above tests were performed in ambient temperature of 25 °C.

Electrodes were 2 mm, 0.6 mm, or 25 μm diameter platinum disks (CH Instruments) or a cochlear implant with 22 half band, 0.3 mm² nominal area platinum electrodes (donated by Cochlear, Ltd.). One electrode of each type was tested. The electrodes were freshly polished before every experiment ensuring reproducible starting conditions. Disk electrodes were polished with 0.3 μm alumina slurry on Microcloth polishing cloth (Buehler), rinsed in deionised water and gently dried (Kimwipe) before use; the cochlear implant was not mechanically polished before use and had not been used for any in vivo studies. Acid polishing was achieved by cycling the electrode potential from 1.2 to -0.2 V at 50 mV s^-1 for 50 cycles in 0.5 M H₂SO₄. Electrodes were tested in a 3-electrode configuration on a CHI660E potentiostat (CH Instruments) using a Ag/AgCl (3 M KCl) as reference electrode and Pt wire as counter electrode. The electrodes were connected to the potentiostat via alligator clips and placed into a beaker of solution.

All electrochemical experiments were conducted with CHI660E potentiostat (CH Instruments, TX, USA) in a three-electrode system using a lab-built Ag/AgCl electrode as the reference electrode and a Pt wire (Alfa Aesar, MA, USA) as the counter electrode. Each experiment was conducted with at least 4 nanopipets in triplicate (at least 12 runs in total).