Modulating basal ganglia circuitry is of great significance in the improvement of motor function in Parkinson’s disease (PD). Here, for the first time, we demonstrate that noninvasive ultrasound deep brain stimulation (UDBS) of the subthalamic nucleus (STN) or the globus pallidus (GP) improves motor behavior in a subacute mouse model of PD induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Immunohistochemical c-Fos protein expression confirms that there is a relatively high level of c-Fos expression in the STN-UDBS and GP-UDBS group compared with sham group (both p < 0.05). Furthermore, STN-UDBS or GP-UDBS significantly increases the latency to fall in the rotarod test on day 9 (p < 0.05) and decreases the time spent climbing down a vertical rod in the pole test on day 12 (p < 0.05). Moreover, our results reveal that STN-UDBS or GP-UDBS protects the dopamine (DA) neurons from MPTP neurotoxicity by downregulating Bax (p < 0.001), upregulating Bcl-2 (p < 0.01), blocking cytochrome c (Cyt C) release from mitochondria (p < 0.05), and reducing cleaved-caspase 3 activity (p < 0.01) in the ipsilateral substantia nigra (SN). Additionally, the safety of ultrasound stimulation is characterized by hematoxylin and eosin (HE) and Nissl staining; no hemorrhage or tissue damage is detected. These data demonstrate that UDBS enables modulation of STN or GP neural activity and leads to neuroprotection in PD mice, potentially serving as a noninvasive strategy for the clinical treatment of PD.

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We report a metasurface for focusing reflected ultrasonic waves over a wide frequency band of 0.45–0.55 MHz. The broadband focusing effect of the reflective metasurface is studied numerically and then confirmed experimentally using near-field scanning techniques. The focusing mechanism can be attributed to the hyperboloidal reflection phase profile imposed by different depths of concentric grooves on the metasurface. In particular, the focal lengths of the reflective metasurface are extracted from simulations and experiments, and both exhibit good linear dependence on frequency over the considered frequency band. The proposed broadband reflective metasurface with tunable focal length has potential applications in the broad field of ultrasonics, such as ultrasonic tomographic imaging, high intensity focused ultrasound treatment, etc.

We present the acoustophoretic motion of microparticles simultaneously driven by the acoustic streaming induced drag force (ASF) and acoustic radiation force (ARF) on a phononic crystal plate (PCP). A much faster acoustophoresis can be achieved via a PCP than a traditional standing wave in bulk and surface acoustic wave devices. The mechanism is attributed to the significantly enhanced ASF and ARF originating from the resonant excitation of a nonleaky zero-order antisymmetric Lamb mode intrinsically in the plate, which generates the highly localized field vertical to the surface and periodic field parallel to the surface. We also demonstrate the transition from the ASF dominated acoustophoresis to ARF dominated acoustophoresis as a function of particle size. The predicted trajectories and velocity of acoustophoretic particles by the proposed finite element model are in reasonable agreement with experimental phenomena. This study would aid the development of simple, scalable, integrated, and disposable phononic crystal based acoustofluidic systems for biomedical applications such as rapid mixing, cell trapping, sorting, and patterning.

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Acoustic manipulation of particles, as a non-contact and non-damage method, has attracted much interest in recent years. Here, we present a platform for sound-driven particle delivery realized on an artificially engineered metal plate with manipulated, graded acoustic field distribution. By fabricating gratings with graded height on one surface of the structured plate, we obtain graded acoustic pressure distribution near the smooth surface of the plate. The acoustic field can be tuned at different positions by regulating the operating frequency, which originates from the gratings of different heights corresponding to different resonant frequencies. Therefore, from the effect of the acoustic radiation force exerted by this gradient field, a particle will transfer on the plate just by the frequency being tuned, without moving the acoustic source. Our theoretical analysis agrees well with the experimental demonstration. This work will lead to potential applications in drug delivery and microfluidics.