Fig. 1. Optoelectric neural interface experimental system. (a) Concurrent optogenetic stimulation and electrophysiological recording system; (b) schematic of the proposed optoelectric neural interface; (c) optical micrograph of an assembled optoelectrode; (d) schematic cross-section of the ultra-flexible electrode

Fig. 2. Characterization of the optical performance of the flat-port and tapered fibers. (a) Schematic diagrams of scattering of flat-port fiber (FF) and tapered fiber (TF); (b) simulation of the output light power density of the flat and tapered fibers, respectively; (c)(d) experimental demonstration of the light scattering from the flat-port and tapered fibers, respectively; (e) normalized scattered light intensity along the core direction of the flat-port and tapered fibers

Fig. 3. In vitro characterization of photoelectric artifacts. (a) Digital picture of the facility for in vitro signal acquisition; (b) an example of LFP and AP frequency bands during light irradiation; (c) raw trace of photoelectric artifacts in different channels; (d) raw trace of photoelectric artifacts in the gels with different mass concentrations of milk powder; (e) raw trace of photoelectric artifacts at different optical powers; (f) histogram of photoelectric artifact peaks in different channels (optical power: 20 mW, mass concentration of milk powder: 50 mg/mL); (g) peak value of photoelectric artifacts in the gels with different mass concentrations of milk powder (optical power: 20 mW); (h) peak values of photoelectric artifacts of the LFP band at different optical powers; (i) peak values of photoelectric artifacts of the AP band at different optical powers; (j) power spectral density of photoelectric artifacts at different optical powers; (k) power spectral density of photoelectric artifacts in the gels with different mass concentrations of milk powder

Fig. 4. In vivo characterization of photoelectric artifacts. (a) Digital picture of concurrent optical stimulation and electrophysiological recording of mice after optoelectrode implantation (without virus transfection); (b) filtered traces of LFP and AP bands during light irradiation; (c) impedance of the optoelectrode (measurement frequency of 1 kHz) at different time after implantation; (d) peak value of photoelectric artifacts at different optical powers; (e) peak value of photoelectric artifacts in different days after the optoelectrode implantation; (f) power spectral densities of photoelectric artifacts at different channels at 5 mW power (light pulses starting at 0.1 s and lasting for 100 ms); (g) power spectral density of photoelectric artifacts at different optical powers

Fig. 5. Verification of concurrent optogenetic stimulation and electrophysiological recording using the optoelectric neural interface. (a) Schematic diagram of optogenetic stimulation; (b) filtered traces of LFP and AP bands during light stimulation; (c) power spectral density of photoelectric artifacts (light pulses starting at 0.1 s and lasting for 100 ms); (d) spike raster plot of 100 optogenetic stimulation cycles and a typical waveform of a single unit; (e) spike histogram of 100 optogenetic stimulation cycles (light pulses starting at 0.1 s and lasting for 100 ms)