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. 2025 Jul 24;17(15):2018.
doi: 10.3390/polym17152018.

Multi-Objective Optimization of IME-Based Acoustic Tweezers for Mitigating Node Displacements

Hanjui Chang  1   2 , Yue Sun  1   2 , Fei Long  1   2 , Jiaquan Li  1   2
Affiliations

Multi-Objective Optimization of IME-Based Acoustic Tweezers for Mitigating Node Displacements

Hanjui Chang et al. Polymers (Basel). .

Abstract

Acoustic tweezers, as advanced micro/nano manipulation tools, play a pivotal role in biomedical engineering, microfluidics, and precision manufacturing. However, piezoelectric-based acoustic tweezers face performance limitations due to multi-physical coupling effects during microfabrication. This study proposes a novel approach using injection molding with embedded electronics (IMEs) technology to fabricate piezoelectric micro-ultrasonic transducers with micron-scale precision, addressing the critical issue of acoustic node displacement caused by thermal-mechanical coupling in injection molding-a problem that impairs wave transmission efficiency and operational stability. To optimize the IME process parameters, a hybrid multi-objective optimization framework integrating NSGA-II and MOPSO is developed, aiming to simultaneously minimize acoustic node displacement, volumetric shrinkage, and residual stress distribution. Key process variables-packing pressure (80-120 MPa), melt temperature (230-280 °C), and packing time (15-30 s)-are analyzed via finite element modeling (FEM) and validated through in situ tie bar elongation measurements. The results show a 27.3% reduction in node displacement amplitude and a 19.6% improvement in wave transmission uniformity compared to conventional methods. This methodology enhances acoustic tweezers' operational stability and provides a generalizable framework for multi-physics optimization in MEMS manufacturing, laying a foundation for next-generation applications in single-cell manipulation, lab-on-a-chip systems, and nanomaterial assembly.

Keywords: IME technology; NSGA-II-MOPSO; acoustic tweezers; micro/nano manufacturing; multi-objective optimization; thermal–mechanical coupling; wave transmission efficiency.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Acoustic tweezers optimization summary diagram.
Figure 2
Figure 2
PVT comparison diagram of circuit film materials.
Figure 3
Figure 3
Flowchart of NSGA-II-MOPSO.
Figure 4
Figure 4
Acoustic tweezers 3D design.
Figure 5
Figure 5
LHS sampling data.
Figure 6
Figure 6
Influence of three factors on three goals.
Figure 7
Figure 7
Response surface diagrams of the effects of the holding pressure and melting temperature on the node displacement, volume shrinkage rate, and residual stress.
Figure 8
Figure 8
Response surface diagrams of the effects of the holding pressure and holding time on the node displacement, volume shrinkage rate, and residual stress.
Figure 9
Figure 9
Response surface diagrams of the effects of the melting temperature and holding time on the node displacement, volume shrinkage rate, and residual stress.
Figure 10
Figure 10
Pareto solution set for three object values under the NSGA-II-MOPSO method.
Figure 11
Figure 11
Node displacement after NSGA-II-MOPSO optimization.
Figure 12
Figure 12
Residual stress distribution after NSGA-II-MOPSO optimization.
Figure 13
Figure 13
Volumetric shrinkage distribution after NSGA-II-MOPSO optimization.
Figure 14
Figure 14
Optimization ratio chart.
Figure 15
Figure 15
The 20 groups of node displacement before and after optimization.
Figure 16
Figure 16
Schematic diagram of tie bar elongation during the clamping phase.
Figure 17
Figure 17
Cavity pressure curve during the injection molding cycle.
See this image and copyright information in PMC

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