Multifunctional Fiber‐Based Optoacoustic Emitter as a Bidirectional Brain Interface
Nan Zheng, Ying Jiang, Shan Jiang, Jongwoon Kim, Guo Chen, Yueming Li, Ji‐Xin Cheng, Xiaoting Jia, Chen Yang
Advanced Healthcare Materials 2023 · 10.1002/adhm.202300430
Abstract
A bidirectional brain interface with both "write" and "read" functions can be an important tool for fundamental studies and potential clinical treatments for neurological diseases. Herein, a miniaturized multifunctional fiber-based optoacoustic emitter (mFOE) is reported thatintegrates simultaneous optoacoustic stimulation for "write" and electrophysiology recording of neural circuits for "read". Because of the intrinsic ability of neurons to respond to acoustic wave, there is no requirement of the viral transfection. The orthogonality between optoacoustic waves and electrical field provides a solution to avoid the interference between electrical stimulation and recording. The stimulation function of the mFOE is first validated in cultured ratcortical neurons using calcium imaging. In vivo application of mFOE for successful simultaneous optoacoustic stimulation and electrical recording of brain activities is confirmed in mouse hippocampus in both acute and chronical applications up to 1 month. Minor brain tissue damage is confirmed after these applications. The capability of simultaneous neural stimulation and recording enabled by mFOE opens up new possibilities for the investigation of neural circuits and brings new insights into the study of ultrasound neurostimulation.
Abstract via europepmc.
Exposures
Exposure 1: Optoacoustic stimulation of cultured rat cortical neurons
Target: cultured neurons — “rat cortical neurons”
Device: custom-built · multifunctional fiber-based optoacoustic emitter (mFOE) ✓
| Waveform | other patterned | |
|---|---|---|
| Fundamental frequency (kHz) | 12,500 | ✓✓✓⚑ |
| Pulse duration (ms) | 0.00008 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 1,700 | ✓✓✓ |
| Duty cycle (%) | not reportedpulse duration × PRF gives 0.014% | |
| Sonication duration (s) | 0.005, 0.05, 0.1, 0.2swept | ✓✓✓⚑ |
| Free-field pressure (kPa) | 2,300 | ✓✓✓⚑ |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not applicable | |
| In-situ pressure (kPa) | not applicable | |
| In-situ Isppa (W/cm²) | not applicable | |
| In-situ Ispta (W/cm²) | not applicable |
1030 nm, 3 ns laser pulses at 1.7 kHz delivered in bursts of 5, 50, 100 or 200 ms (41.8 uJ per pulse); 5 bursts at 1 s intervals in the reproducibility test. Acoustic pulse width about 0.08 us (single laser pulse); only 50 ms or longer evoked calcium responses.
Exposure 2: Optoacoustic stimulation of mouse hippocampus with implanted mFOE
Target: hippocampus — “hippocampus”
Device: custom-built · multifunctional fiber-based optoacoustic emitter (mFOE) ✓
| Waveform | other patterned | |
|---|---|---|
| Fundamental frequency (kHz) | 12,500 | ✓✓✓ |
| Pulse duration (ms) | 0.00008 | ✓✓✓ |
| Pulse repetition frequency (Hz) | 1,700 | ✓✓✓ |
| Duty cycle (%) | not reportedpulse duration × PRF gives 0.014% | |
| Sonication duration (s) | 0.05 | ✓✓✓ |
| Free-field pressure (kPa) | 2,300 | ✓✓✓⚑ |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
50 ms bursts of 1030 nm, 3 ns laser pulses (41.8 uJ, 1.7 kHz repetition rate) delivered at 1 Hz during a 5 second treatment period, at 3 days, 7 days, 2 weeks and 1 month after implantation.
Flags from extraction
exposures[0].fundamental_frequency_khz— Broadband optoacoustic pulse; 12.5 MHz is the stated peak of the spectrum, recorded as the frequencyexposures[0].free_field.pressure_kpa— Peak-to-peak pressure (2.3 MPa) measured by hydrophone in water at 41.8 uJ; 1.0 and 1.6 MPa at lower energies; not peak negativeexposures[1].free_field.pressure_kpa— Water measurement carried over by the paper's reported pulse energy (41.8 uJ), not measured in tissueexposures[0].timing.pulse_duration_ms— Acoustic pulse width about 0.08 us given in us; laser pulse is 3 ns; duty cycle not statedexposures[0].timing.sonication_duration_s— Burst durations 5, 50, 100, 200 ms sweptn_subjects— 5 mice implanted for stimulation; cultures counted as N = 15 stimulation events; separate mice for histology and controlssham_type— Laser-only control with fiber lacking optoacoustic coating, plus a dead-brain control
Notes: Optoacoustic (fiber laser) rather than transducer ultrasound; two exposures by target.