Plasmon-enhanced photoacoustic oscillation for micro laser motor actuation

Abstract

Flexible micro/nano motors responsive to light sources are highly desirable. Conventional photothermal (PT) techniques have provided significant light-actuation methods; however, the dynamic responses of these devices in high frequency domain are severely restricted by the frequency response limitation. To overcome this limitation, the thermal-, electric-, and acoustic-near field interactions in the PT process and its accompanied photoacoustic (PA) process are investigated, and a plasmon enhanced PA actuation method is proposed. The significant improvement in PA oscillation by strong localized surface plasmon resonance provides a powerful means to realize a broadband response laser motor without the frequency response limitation. This PA laser motor could generate PA oscillation of over 5 µm by pulse laser with repetition frequencies of 1 Hz to 20 kHz and has a maximum value of 18.8 µm at the mechanical resonant frequency. It demonstrates the effectiveness of this PA laser motor in offsetting the shortcomings of the PT actuation method. The device requires no electrical or chemical energy, and it has potential benefits, such as bionic research into insect flapping, vocal-cord vibration, and muscular movement in fields including micro/nano physics, biochemistry, and clinical medicine.