Fig. 2: Mechanisms of TRAIN strategy.
From: Anisotropic hydrogel microelectrodes for intraspinal neural recordings in vivo
a Illustration of the Stimulated Raman Scattering (SRS) microscopy setup, highlighting the path of the laser, the sample interaction, and signal detection components. b Comparative two-color SRS images of untrained CNTs (0.16 wt%)-PVA hydrogel and TRAIN CNTs (0.24 wt%)-PVA hydrogel. Scale bars: 20 µm. c Raman spectra displaying the characteristic G-band of CNTs within the TRAIN CNTs (0.16 wt%)-PVA hydrogel film compared to the PVA hydrogel film. d Representative probability of CNTs orientations calculated from b. e Dispersion degrees of untrained CNTs (0.16 wt%)-PVA hydrogel and TRAIN CNTs (0.24 wt%)-PVA hydrogel. Data are presented as mean ± s.d., n = 8 individual hydrogel samples for untrained group, and n = 12 individual hydrogel samples for TRAIN group. Two-tailed unpaired Student’s t-test was used to determine statistical analysis: F7,11 = 9.794, t = 9.216, df = 18, α = 0.05, ****p < 0.0001. f Conductivity mechanisms in TRAIN CNTs-PVA hydrogel film along the x, y, and z directions, respectively. g Left: A schematic of electrochemical characterization of TRAIN CNTs-PVA hydrogel film in x and y directions and an image of the characterization device. Scale: 1 mm. Right: An illustration of electrochemical characterization of TRAIN CNTs-PVA hydrogel film in z direction and an image of characterization device. Scale: 1 mm. WE: working electrode, RE: reference electrode, CE: counter electrode. h Specific impedance changes (post-training/pre-training) of TRAIN CNTs-PVA hydrogels in x, y, z directions. i Wide-angle X-ray spectroscopy (WAXS) patterns of pre-and post-20% trained CNTs-PVA hydrogel fibers. The break at 180o indicates the beam splits from the instrument. j Elastic modulus of untrained CNTs (0.16 wt%)-PVA hydrogel fibers and TRAIN CNTs (0.16 wt%)-PVA hydrogel fibers. Data are presented as mean ± s.d., n = 8 individual hydrogel fibers. One-way ANOVA was used to determine statistical analysis: F3, 28 = 15.36, ****p < 0.0001. k Maximum elongation of untrained CNTs (0.16 wt%)-PVA hydrogel fibers and TRAIN CNTs (0.16 wt%)-PVA hydrogel fibers. Data are presented as mean ± s.d., n = 8 individual hydrogel fibers. One-way ANOVA was used to determine statistical analysis: F3, 28 = 9.364, ***p = 0.0002. l Differential scanning calorimetry (DSC) curve of PVA and CNTs-PVA (0.16 wt% and 0.24 wt%) materials.
