Near-field Acoustic Manipulation

Non-contact actuators are promising technologies in metrology, machine-tools, and hovercars, but have been suffering from low energy efficiency, complex design, and low controllability. This research explores the possibility to use near-field acoustic force to levitate and drive objects with only mechanical vibration.

The levitation is achieved by creating a stable air film using near-field acoustic force; while the non-contact driving is realized by controlling the pressure distribution within the air film using coupled resonant mode. We have demonstrated the prototypes in surface actuators (2D) (Chen et al., 2016) (missing reference) and a non-contact spindle (Guo & Gao, 2018).

We also studied the dynamic characteristics of near field levitation bearings. Through theoretical analysis, two different types of system stiffness are defined and derived analytically. The dynamic stiffness relates the excitation amplitude to the dynamic force amplitude, while the effective stiffness governs the time-averaged force–displacement relationship. The results indicate two non-linear and asymmetric spring constants that can effectively predict levitation force and height (Wang & Guo, 2021).

Building on this foundation, we recently extended near-field acoustic manipulation to contactless semiconductor die handling. A multi-island air-film segmentation breaks the <4 mm object-size limit of attractive near-field gripping, enabling stable non-contact pickup of an 8 × 8 mm silicon die at 522 N/m vertical stiffness — doubling the prior size limit and offering a step toward particle-free advanced packaging (Wang et al., 2026).

The potential applications of near field acoustic levitation and manipulation span precision machine tools, contactless semiconductor die handling, and other settings where particle-free, non-contact manipulation is required.

2026

Near-field acoustic gripping for contactless semiconductor die handling

Yaoke Wang , Ziming Zhao , Yi Shi , and Ping Guo

CIRP Annals, Oct 2026

Abstract PDF Video

This study presents near-field acoustic gripping for contactless semiconductor die handling. Existing near-field acoustic attraction fails for larger objects because repulsive squeeze pressure overwhelms attractive edge effects. A mechanistic model resolving these competing forces is presented to explain the geometric size constraint. To address the size limitation, a scalable multi-island design that segments the air film is proposed to maintain the attractive regime. Experiments demonstrate stable pickup of an 8 by 8 millimeter silicon die, doubling the known size limit. The system achieves a high vertical stiffness of 522 N/m and withstands 0.7 g lateral acceleration, validating its potential for advanced packaging.

2021

Stiffness modeling for near field acoustic levitation bearings

Yaoke Wang , and Ping Guo

Applied Physics Letters, Oct 2021

Abstract PDF

The dynamic characteristics of near field levitation bearings have been investigated in this study. Through theoretical analysis, two different types of system stiffness are defined and derived analytically. The dynamic stiffness relates the excitation amplitude to the dynamic force amplitude, while the effective stiffness governs the time-averaged force–displacement relationship. The results indicate two non-linear and asymmetric spring constants that can effectively predict levitation force and height. The models are verified with a carefully designed experimental setup to eliminate the structural resonance effect. Besides, some unique dynamic behaviors are investigated and predicted based on the proposed stiffness model.

2018

An active non-contact journal bearing with bi-directional driving capability utilizing coupled resonant mode

Ping Guo , and Han Gao

CIRP Annals, Oct 2018

Abstract PDF Video

Non-contact journal bearings are conventionally based on pressurized air or magnetic levitation. This paper reports on a new design of an active non-contact journal bearing with bi-direction driving capabilities. It combines the functions of an axis positioner, non-contact journal bearing, and rotary motor utilizing coupled vibration modes. The shaft levitation is achieved by creating a stable air film using near-field acoustic force; while the non-contact rotation is realized by controlling the pressure distribution within the air film using coupled resonant mode. The essential design methodology and theoretical principles are presented along with the performance evaluation of the functional prototypes.

2016

Self-running and self-floating two-dimensional actuator using near-field acoustic levitation

Keyu Chen , Shiming Gao , Yayue Pan , and Ping Guo

Applied Physics Letters, Oct 2016

Abstract PDF Video

Non-contact actuators are promising technologies in metrology, machine-tools, and hovercars, but have been suffering from low energy efficiency, complex design, and low controllability. Here we report a new design of a self-running and self-floating actuator capable of two-dimensional motion with an unlimited travel range. The proposed design exploits near-field acoustic levitation for heavy object lifting, and coupled resonant vibration for generation of acoustic streaming for non-contact motion in designated directions. The device utilizes resonant vibration of the structure for high energy efficiency, and adopts a single piezo element to achieve both levitation and non-contact motion for a compact and simple design. Experiments demonstrate that the proposed actuator can reach a 1.65 cm/s or faster moving speed and is capable of transporting a total weight of 80 g under 1.2 W power consumption.

References

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