Pgstat204 potentiostat

The spectrometer used was a USB 2000 Fiber Optic Spectrometer (Ocean Optics). The light source that was a DH-2000-BAL deuterium-halogen (Ocean Optics) was guided through the optical fiber of 600 μm in diameter (Ocean Optics, USA). The light beam was collimated using optical lenses (Thorlabs; focal length, 2 cm) before and after the transmission of the beam through the electrochemical cell. The light beam passed through the electrochemical cell slightly above the water-TFT interface, i.e., through the aqueous phase. The interfacial Galvani potential difference ( ${\mathrm{\Delta }}_{\mathrm{o}}^{\mathrm{w}}\mathrm{\varphi }$ ) was controlled using an Autolab PGSTAT204 potentiostat (Metrohm, Switzerland).

First, the current–voltage (I–V) curves of PEGDMA, PEGDMA with randomly distributed CNTs and PEGDMA with dielectrophoretically aligned CNTs were obtained using the two-probes of a source/measure unit (B2902A, Keysight, ABD) connected to a computer. The measurement was performed in a Faraday cage at room temperature to reduce noise. The voltage was swept between −2 and 2 V at a scan rate of 0.1 V and the resulting current was recorded. All the hydrogels were formed on Au-IDA chips and the measurements were conducted using the connection pads of the chips. Next, electrochemical impedance spectroscopy (EIS) measurements were performed for the same test groups using an Autolab PGSTAT204 potentiostat (Metrohm, Netherlands). The data were monitored and analyzed using Autolab Nova software. Impedance spectra of all the samples were recorded on the Au-IDA chips over a frequency range of 1 to 100 Hz with a 25 mV perturbation amplitude.