Contactless pick-and-place of millimetric objects using inverted near-field acoustic levitation

Abstract

We model and realize an ultrasonic contactless pick-and-place device capable of picking, self-centering, self-orienting, translating, and releasing flat millimetric objects. The device is an ultrasonic Langevin transducer operating at 21 kHz that radiates into air through a tapered tip. Objects are trapped few micrometers below the tip due to the near-field acoustic levitation phenomenon. We first investigate the conditions to achieve an attractive force on the object depending on its size and the device operating frequency. Second, we use a 3D acoustic model that describes the converging forces and torque that provide the self-centering and self-orienting capabilities. Third, a more advanced Computational Fluid Dynamics model based on the Navier-Stokes equations explains the small gap between the tip and the trapped object. The contactless manipulation capabilities of the device are demonstrated by picking, transporting, and releasing a Surface Mount Device in air. The presented manipulation concept can be an interesting alternative for manipulating delicate objects such as microelectromechanical devices, silicon dies, or micro-optical devices.

Viscoacoustic squeeze-film force on a rigid disk undergoing small axial oscillations

“…The velocity field is potential and can be correspondingly determined for each geometrical configuration with use of conformal mapping techniques (Birkhoff & Zarantonello 1957;Gurevich 1966). Note that since P0 ∝ cos τ , the time-averaged pressure is identically zero at this order.…”

“…Of particular interest is the form of C 1 near the origin of the diagram, which corresponds to weakly compressible systems operating near the lubrication limit. In the associated double limit Λ α 2 1, the film force is given by Taylor & Saffman (1957) and (b) time-dependent direct numerical simulations conducted by Andrade et al (2020) (both denoted by dots). For the former case, the dimensionless force is plotted against the squeeze number and for the latter, the dimensional force is plotted against the mean gap width.…”

“…The dependence of the steady squeeze-film force acting on the oscillating bodywhich accounts for comparable pressure contributions from the two distinct flow regions -on the three governing parameters is discussed in § 7 with specific attention dedicated to the criteria required for a transition between levitative and adhesive forces. The force predicted by our asymptotic analysis is compared with that determined in the recent direct numerical simulations of Andrade et al (2020). Closed form analytical expressions facilitatory for low-cost computation of the steady film pressure and squeeze-film force are provided in an appendix, and finally, concluding remarks are given in § 8.…”

Contactless Picking of Objects Using an Acoustic Gripper

“…Pressure Distribution (VTT) For implementing an acoustic gripper, it is necessary to automatically insert objects into the acoustic field in a controlled manner [23]. This work demonstrates acoustic grippers for different boundary conditions, namely, for high-density objects placed on acoustically transparent surfaces and low-or medium-density objects placed on reflective surfaces.…”

Acoustic levitation in mid-air: Recent advances, challenges, and future perspectives

“…Another promising application is to use acoustic levitation for producing amorphous drugs with enhanced solubility. 63,64 On the other hand, contactless picking and placing of fragile components can be performed by inverted-near-field acoustic levitation 56,65 and replace current methods based on vacuum suckers that can scratch, shock, or cross-contaminate sensitive components. Another emergent research topic is displays made up of levitating particles acting as physical voxels or tracers: from uniform groups of particles, 19 charts 66 and props 67 to fast-moving particles with persistence of vision.…”