Department of Chemistry, Boston University, Boston, MA, 02215, USA.
Department of Electrical and Computer Engineering, Boston University, Boston, MA, 02215, USA.
Adv Sci (Weinh). 2024 Sep;11(35):e2405677. doi: 10.1002/advs.202405677. Epub 2024 Jul 12.
Photoacoustic (PA) emitters are emerging ultrasound sources offering high spatial resolution and ease of miniaturization. Thus far, PA emitters rely on electronic transitions of absorbers embedded in an expansion matrix such as polydimethylsiloxane (PDMS). Here, it is shown that mid-infrared vibrational excitation of C─H bonds in a transparent PDMS film can lead to efficient mid-infrared photoacoustic conversion (MIPA). MIPA shows 37.5 times more efficient than the commonly used PA emitters based on carbon nanotubes embedded in PDMS. Successful neural stimulation through MIPA both in a wide field with a size up to a 100 µm radius and in single-cell precision is achieved. Owing to the low heat conductivity of PDMS, less than a 0.5 °C temperature increase is found on the surface of a PDMS film during successful neural stimulation, suggesting a non-thermal mechanism. MIPA emitters allow repetitive wide-field neural stimulation, opening up opportunities for high-throughput screening of mechano-sensitive ion channels and regulators.
光声（PA）发射器是新兴的超声源，具有高空间分辨率和易于小型化的特点。到目前为止，PA 发射器依赖于嵌入扩展矩阵（如聚二甲基硅氧烷（PDMS））中的吸收体的电子跃迁。本文表明，透明 PDMS 薄膜中 C─H 键的中红外振动激发可以导致高效的中红外光声转换（MIPA）。与常用的基于嵌入 PDMS 中的碳纳米管的 PA 发射器相比，MIPA 的效率高 37.5 倍。通过 MIPA 成功地进行了广泛场的神经刺激，刺激半径可达 100 µm，并且可以达到单细胞精度。由于 PDMS 的热导率低，在成功的神经刺激过程中，PDMS 薄膜表面的温度升高不到 0.5°C，表明存在非热机制。MIPA 发射器允许重复的广域神经刺激，为机械敏感离子通道和调节剂的高通量筛选开辟了机会。
