Search

We demonstrate the boosting of quality factor (Q) of a aligned Aluminum Nitride (AlN) on Silicon (Si) laterally vibrating resonator (LVR) by using wide acoustic bandgap (ABG) phononic crystal (PnC) anchors. To date, Q-boosting strategies have been studied predominantly for the common orientation. Given the anisotropy of Si, changing orientation could notably affect the effectiveness of Q-boosting strategies. We show experimentally that Qs of aligned LVRs more than doubled to 10000 with the PnC anchors. To further corroborate the effectiveness of the PnCs, we also incorporated the PnCs into delay lines with wave propagation along the axis, showing that the PnCs provide large acoustic attenuation of 45 dB.

Acoustofluidic platforms typically enable only rectangular matrix-like of particle patterns in a closed microchamber actuated by a surface acoustic wave (SAW) device. More complex and unique patterns require a sophisticated and dedicated SAW transducer. As a first, we demonstrate the generation of ring-shape particle patterns on-chip actuated by a simple generic SAW transducer. The ability to reshape unique acoustic field on-chip is realized by using a bulk micromachined microelectromechanical systems (MEMS) chip. We also show for the first time the creation of a two-dimensional (2D) pattern with just a one-dimensional (1D) standing SAW (SSAW). These results pave the way toward truly plug-and-play acoustofluidics, where unique patterns are defined by a diverse range of interchangeable chips on a standard SAW transducer.

Phononic crystals (PnC) can help shape acoustic fields to enhance microfluidic functions in acoustofluidic devices. But operating within the defined phononic band gap (PBG) limits the scope for optimizing microfluidic functions. We show, for the first-time, efficient droplet centrifugation that works outside the range of the PBG. Instead of using deep reactive ion etching (DRIE) to create the PnC, we here use laser machining with the aim to demonstrate low cost and rapid prototyping of complex superstrates that can enhance particle concentration greatly. The results of this work are significant given that the center frequency of a PBG is tied to the size of the PnC. In the case of particle concentration, the efficiency increases with frequency. As such, working in the confines of a PBG requires a high level of precision in fabrication. The ability to work outside PBGs removes such restrictions, opening a range of possibilities. Besides, the results are based on a two-chip approach that yields a low-cost solution for disposable single-use acoustofluidics.

We report the first demonstration of two-dimensional (2D) patterning of microparticles on a silicon superstrate via a plug-and-play reusable acoustofluidic setup. The proposed integrated device comprises two independent parts: (1) a silicon superstrate enclosed in a PDMS microfluidic chamber (containing the particles) and (2) a reusable lithium niobate (LN) piezoelectric substrate for generating standing surface acoustic waves (SSAW). The proposed method enables patterning of particles on a silicon superstrate with the aim of ultimately enabling 2D patterning of particles or cells on functional silicon micromechanical chips. Such a capability would enable functional applications such as diagnostics and biosensing. This contactless, label-free, low-cost technique would be widely employed in biological application regardless of shape, size, charge or polarity of samples.

This paper reports the first demonstration of acoustic tweezers to manipulate microparticles in a sessile droplet over a functional surface-micromachined silicon chip fabricated with polysilicon micromechanical sensing structures. The proposed plug-and-play setup comprises two interchangeable parts: a detachable silicon micromachined sensor chip (acting as a superstrate) and a surface acoustic wave (SAW) device substrate. The SAW device provides the off-chip acoustic source from which Rayleigh waves couple into the functional silicon chip. We demonstrate concentration of initially randomly dispersed microparticles in a water droplet loaded on the functional silicon chip by means of acoustic streaming forces using a drive power of 1 W.

This paper describes a magnetically-driven rotating triboelectric generator (M-TEG) as a direct power source for wireless sensors. Four M-TEGs are symmetrically placed on the wheel hub of a vehicle. Permanent magnets mounted on the brake caliper provide a non-contact magnetic force to generate a seesaw-like swing motion of the M-TEG in the tire. The unique advantage of the seesaw structure eliminates the influence of a large centrifugal force at a high rotating speed. High electrical output has been achieved in the wide ranges of rotation speed. The M-TEG at the rotation speed of 100 rpm can deliver a maximal output voltage of 316 V and power of 22.3 mW under a constant magnetic field strength of 0.2 T. There is no obvious decrease in the output voltage of the M-TEG after continuous working for more than 12 h. The power generated by the TEG is stored in a capacitor and the stored energy is used to drive MEMS pressure sensor. The M-TEG has also demonstrated to power a commercial wireless sensor for sending the real-time temperature information to a receiver and displaying on a monitor.