Micromanipulation Method Research Articles

Movable surface acoustic wave tweezers: a versatile toolbox for micromanipulation

Surface acoustic wave (SAW) tweezers are a promising multifunctional micromanipulation method that controls microscale targets via patterned acoustic fields. Owing to their device structure and bonding process, most SAW tweezers have limitations in terms of controlling the position and motion of the acoustic traps, as they generate an acoustic field with a fixed region and adjust the manipulation effects via signal modulation. To address this challenge, we propose movable SAW tweezers with a multilayer structure, achieving dynamic control of their wave field and acoustic trap positions; we demonstrate their precise manipulation functions, such as translation, in-plane rotation, out-of-plane rotation, and cluster formation, on a wide spectrum of samples, including particles, bubbles, droplets, cells, and microorganisms. Our method not only improves the degree of freedom and working range of SAW tweezers but also allows for precise and selective manipulation of microtargets via microtools and localized wavefields. Owing to their flexibility, versatility, and biocompatibility, the movable SAW tweezers can be a practical platform for achieving arbitrary manipulation of microscale targets and have the potential to play significant roles in biomedical microrobotics.

A Micromanipulation-Actuated Large-Scale Screening to Identify Optimized Microphysiological Model Parameters in Skeletal Muscle Regeneration.

Hydrogel-based 3D cell cultures are extensively utilized to create biomimetic cellular microstructures. However, there is still lack of effective method for both evaluation of the complex interaction of cells with hydrogel and the functionality of the resulting micro-structures. This limitation impedes the further application of these microstructures as microphysiological models (microPMs) for the screening of potential culture condition combinations to enhance the skeletal muscle regeneration. This paper introduces a two-probe micromanipulation method for the large-scale assessment of viscoelasticity and contractile force (CF) of skeletal muscle microPMs, which are produced in high-throughput via microfluidic spinning and 96-well culture. The collected data demonstrate that viscoelasticity parameters (E* and tanδ) and CF both measured in a solution environment are indicative of the formation of cellular structures without hydrogel residue and the subsequent generation of myotubes, respectively. This study have developed screening criterias that integrate E*, tanδ, and CF to examine the effects of multifactorial interactions on muscle fiber repair under hypoxic conditions and within bioprinted bipennate muscle structures. This approach has improved the quality of hypoxic threshold evaluation and aligned cell growth in 3D. The proposed method is useful in exploring the role of different factors in muscle tissue regeneration with limited resources.

Frequency-selective acoustic micromanipulation platform

Acoustic micromanipulation methods offer versatile tools ranging from lab-on-chip diagnostic platforms to mobile microrobots. Acoustically oscillating bubble-powered microsystems are gaining increased attention owing to their low cost and convenient operation. To date, no studies have reported on the controllability of the driving frequency on acoustic micromanipulation platforms using Helmholtz resonators. Here, we introduce a Helmholtz resonant cavity into a bubble-powered microsystem to reveal the function of the oscillation modes and frequency selectivity. The Su–Schrieffer–Heeger (SSH) model was utilized to construct a topological interfacial state and bubble-powered working location. We experimentally observed that the microparticles were captured by the oscillation bubble and underwent orbital rotation at the topological frequency. However, the microparticles were tightly bound close to the oscillation bubble area when the driving frequency was outside the topological frequency range. Our acoustic micromanipulation platform implements multiple microparticle manipulation modes based on frequency selectivity that are independent of optical or magnetic properties, which can enrich the micromanipulation toolbox and exhibit enormous application potential in the biomedical field.

Dynamic modeling and optimization of mechanical drift for compliant parallel micromanipulation driven by V-shape linear ultrasonic motors

Designing micro-mechanisms that satisfy large strokes, high precision, and multiple degrees of freedom has consistently been a research focus and challenge in the field of micromanipulation systems. Linear ultrasonic motors (LUMs), with advantages such as millimeter-level travel, nanometer-level motion resolution, and power-off self-locking, significantly contribute to the advancement in the mechanism design of micromanipulation systems. However, the challenge of mechanical drift lacks a comprehensive theoretical analysis to explain its cause and limits its application. This paper presents a mechanical drift modeling method for a compliant parallel micromanipulation (CPM) driven by a LUM. The model primarily focuses on the creep characteristics of the flexure clamp element in the LUM. Based on the stiffness matrix analysis method of the compliant parallel mechanism kinematics, the mechanical drift dynamics model of the CPM is established. The influence of the main structural parameters on the CPM mechanical drift is investigated. The research indicates that the creep of flexure clamps in the CPM is the main factor leading to the mechanical drift. Optimization of mechanical drift is achieved by choosing flexure clamps with higher tangential stiffness for LUM and flexure hinge joints with greater flexibility for CPM. Finally, experimental studies reveal that under equivalent conditions, the mechanical drift of the optimized CPM was significantly reduced than before, proving the rationality of the theoretical model and optimization method.

High-Speed Cell Assembly with Piezo-Driven Two-Finger Microhand

In the past few decades, researchers have conducted extensive studies on cell micromanipulation methods. However, there has consistently been a lack of a micromanipulation system that excels in both precision and speed. Additionally, many of these methods rely on manual control, thus significantly reducing efficiency. In this paper, a robotized micromanipulation system employing a two-finger microhand is proposed. The microhand has a 3-DoF parallel mechanism driven by three piezoelectric actuators, enabling high-precision micromanipulation. Replacing the needle-tip end-effector with a hemispherical end-effector makes cell grasping easier and more stable. In addition, a vibration-based release method combined with gel coating is proposed to reduce the release difficulty caused by adhesion forces. Through multiple sets of experiments, we have determined the optimal grasping and releasing conditions while balancing precision, stability, and damage degree to cells. An automated cell assembly strategy based on microscopic visual feedback and pick-and-place path planning is proposed to achieve the robotized high-speed cell array. Hela cells were chosen as the operation objects, achieving a 95% success rate in grasping and a 97% success rate in releasing. A “T” letter array formed by cells was successfully assembled with an average grasp and release time of less than 0.8 s and an assembly accuracy of 4.5 μm for a single cell. This study holds significant implications for the fields of biology and medicine, presenting potential applications in tissue engineering.

Self-Alignment Capillary Gripper for Microfiber Manipulation

The assembly and arrangement of microfibers have wide applications in biomedicine, material science, and microsystem. However, current micromanipulation methods for positioning and orientating individual microfibers are complex and hard to use. In this article, we report a novel self-alignment capillary gripper for microfiber manipulation that is facile and convenient. We determine the key parameters of the gripper including the required meniscus volume and the tip aspect ratio of the gripper through both numerical simulation and experimental investigation. A two-stage self-alignment process is employed to achieve high precision. The gripper can pick up and self-align microfibers with an aspect ratio of up to 300:1 at an accuracy of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2.1 \pm 2.0\ \mu \mathrm{m}$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$0.6 \pm 0.6 ^\circ $</tex-math></inline-formula> or better and create highly parallel linear arrays. The gripper is also versatile, where multiple types of microfibers including glass fibers, carbon fibers, dandelion seed fibers, and cat hairs can be picked up and self-aligned. Additionally, the gripper can construct two-dimensional patterns and plug a fiber into a microglass capillary.

Engineering tools for quantifying and manipulating forces in epithelia.

The integrity of epithelia is maintained within dynamic mechanical environments during tissue development and homeostasis. Understanding how epithelial cells mechanosignal and respond collectively or individually is critical to providing insight into developmental and (patho)physiological processes. Yet, inferring or mimicking mechanical forces and downstream mechanical signaling as they occur in epithelia presents unique challenges. A variety of in vitro approaches have been used to dissect the role of mechanics in regulating epithelia organization. Here, we review approaches and results from research into how epithelial cells communicate through mechanical cues to maintain tissue organization and integrity. We summarize the unique advantages and disadvantages of various reduced-order model systems to guide researchers in choosing appropriate experimental systems. These model systems include 3D, 2D, and 1D micromanipulation methods, single cell studies, and noninvasive force inference and measurement techniques. We also highlight a number of in silico biophysical models that are informed by in vitro and in vivo observations. Together, a combination of theoretical and experimental models will aid future experiment designs and provide predictive insight into mechanically driven behaviors of epithelial dynamics.

Intracellular Strain Evaluation-Based Oocyte Enucleation and Its Application in Robotic Cloning

Since the first cloned sheep was produced in 1996, cloning has attracted considerable attention because of its great potential in animal breeding. Somatic cell nuclear transfer (SCNT) is widely used for creating clones. However, SCNT is very complicated to manipulate and inevitably causes intracellular damage during manipulation. Typically, only less than 1% of reconstructed embryos develop into live cloned animals. This low success rate is considered to be the major limitation in the extensive application of cloning techniques. In this study, we proposed an intracellular strain evaluation-based oocyte enucleation method to reduce potential intracellular damage in SCNT. We first calculated the intracellular strain based on the intracellular velocity field and then used the intracellular strain as a criterion to improve the enucleation operation. We then developed a robotic batch SCNT system to apply this micromanipulation method to animal cloning. Experimental results showed that we increased the blastocyst rate from 10.0% to 20.8%, and we successfully produced 17 cloned piglets by robotic SCNT for the first time. The success rate of cloning was significantly increased compared to that of traditional methods (2.5% vs 0.73% on average). In addition to the cloning technique, the intracellular strain evaluation-based enucleation method is expected to be applicable to other biological operations and for establishing a universal cell manipulation protocol to reduce intracellular damage.

Pigs with an INS point mutation derived from zygotes electroporated with CRISPR/Cas9 and ssODN.

Just one amino acid at the carboxy-terminus of the B chain distinguishes human insulin from porcine insulin. By introducing a precise point mutation into the porcine insulin (INS) gene, we were able to generate genetically modified pigs that secreted human insulin; these pigs may be suitable donors for islet xenotransplantation. The electroporation of the CRISPR/Cas9 gene-editing system into zygotes is frequently used to establish genetically modified rodents, as it requires less time and no micromanipulation. However, electroporation has not been used to generate point-mutated pigs yet. In the present study, we introduced a point mutation into porcine zygotes via electroporation using the CRISPR/Cas9 system to generate INS point-mutated pigs as suitable islet donors. We first optimized the efficiency of introducing point mutations by evaluating the effect of Scr7 and the homology arm length of ssODN on improving homology-directed repair-mediated gene modification. Subsequently, we prepared electroporated zygotes under optimized conditions and transferred them to recipient gilts. Two recipients became pregnant and delivered five piglets. Three of the five piglets carried only the biallelic frame-shift mutation in the INS gene, whereas the other two successfully carried the desired point mutation. One of the two pigs mated with a WT boar, and this desired point mutation was successfully inherited in the next F1 generation. In conclusion, we successfully established genetically engineered pigs with the desired point mutation via electroporation-mediated introduction of the CRISPR/Cas9 system into zygotes, thereby avoiding the time-consuming and complicated micromanipulation method.

Study on the Manipulation Strategy of Metallic Microstructures Based on Electrochemical-Assisted Method

Microcomponent manipulation (MCM) technology plays a decisive role in assembling complex systems at the micro- and nanoscale. However, the existing micromanipulation methods are difficult to widely apply in the manufacturing of microelectromechanical systems (MEMSs) due to the limited manipulation space and complex application objects, and the manipulation efficiency is relatively low, which makes it difficult to industrialize these micromanipulating systems. To solve the above problems, this paper proposes an efficient metal MCM strategy based on the electrochemical method. To verify the feasibility and repeatability of the strategy, the finite element model (FEM) incorporating the hydrodynamic and electrochemical theories is used to calculate the local stress distribution of the contact position during the dynamic pick-up process. Based on the simulation results, we defined the relationship between the parameters, such as the optimal manipulating position and angle for picking, transferring and releasing. The failure behaviors of pick-up are built to realize the efficient three-dimensional manipulation of microcopper wire of 300 μm. By establishing a theoretical model and experimental verification, it was concluded that the middle point was the best manipulating position when picking up the microcopper wire, the most efficient picking angle was between 45 and 60 degrees for the pipette, and the average time was 480 s in three sets of picking-release manipulation experiments. This paper provides an achievable idea for different types of micro-object manipulations and promotes the rapid application of micromanipulation techniques in MEMSs.

A PZT-Driven 6-DOF High-Speed Micromanipulator for Circular Vibration Simulation and Whirling Flow Generation

Existing micromanipulation methods, whether contact micromanipulation or non-contact micromanipulation, can hardly meet the requirements of low damage and multiple functions in the biomedical field. This study provides a high-speed micromanipulator that can simulate circular vibrations and generate microflow, which could be utilized to actuate non-invasive multiple operations of biological targets at the microscale. We design a PZT-driven 6-DOF micromanipulator with a hybrid structure and flexible hinges. Two 3-PRS parallel modules are serially connected in mirror style to achieve high speed, high accuracy, and a big workspace simultaneously, which enables the highly-controllable circular vibration simulation and strong whirling flow generation. The static, dynamic, and trajectory tracking performances were evaluated. The experimental result showed the 324 × 331 × 40 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> workspace, which was also the range of trajectories that could be generated. Trajectory tracking performance evaluation showed that it could realize ∼200 Hz circular vibration with an error of about 2.4% through open-loop control. Finally, the microflow generation experiment indicated the great potential of the proposed micromanipulator and the method of whirling flow generation in operating the biological targets at the microscale.

All-Purpose Magnetic Micromanipulation System With Two Modes: Chopstick-Like Two-Finger Microhand and Hydrodynamic Tweezer

In the last two decades, the micromanipulation technique has been widely utilized in industrial and biological fields. However, existing micromanipulation methods can hardly meet all the demands in both fields. In this article, we present an all-purpose magnetically driven micromanipulation system with designed contact and noncontact modes for numerous industrial and biological applications, respectively. In the system, a micropipette containing the ferromagnetic beads driven by themagnetic field presentshigh-precision and high-speed motions. With another micropipette, this two-finger microhand can efficiently perform the chopstick-like grasp motion by physical contact. The vibration-based active release relying on the high-speed motion can help release the targets adhering to the end-effector. Besides, local whirling flow surrounding the micropipette induced by high-speed circular motion can trap, transport, and rotate microtargets without contact like a hydrodynamic tweezer to operate micro bio-targets without any damages. In experiments, microbeads are grasped and releasedefficiently in the desired positions using the chopstick-like two-finger microhand mode, and the arrays of a hexagon and “TMECH” have been assembled. The hydrodynamic tweezer mode is adopted to trap, transport, and rotate the microbeads and further applied in the operations of the mouse egg cells. We believe the proposed magnetic micromanipulation system, as an all-purpose tool at the microscale, holds great potential in industrial and biological applications.

In vivo acoustic manipulation of microparticles in zebrafish embryos.

In vivo micromanipulation using ultrasound is an exciting technology with promises for cancer research, brain research, vasculature biology, diseases, and treatment development. In the present work, we demonstrate in vivo manipulation of gas-filled microparticles using zebrafish embryos as a vertebrate model system. Micromanipulation methods often are conducted in vitro, and they do not fully reflect the complex environment associated in vivo. Four piezoelectric actuators were positioned orthogonally to each other around an off-centered fluidic channel that allowed for two-dimensional manipulation of intravenously injected microbubbles. Selective manipulation of microbubbles inside a blood vessel with micrometer precision was achieved without interfering with circulating blood cells. Last, we studied the viability of zebrafish embryos subjected to the acoustic field. This successful high-precision, in vivo acoustic manipulation of intravenously injected microbubbles offers potentially promising therapeutic options.

Label-free rapid isolation of saccharomyces cerevisiae with optically induced dielectrophoresis-based automatic micromanipulation.

Saccharomyces cerevisiae is well-known in the baking and brewing industries and always used for the preparation of probiotics, especially its subtype, Saccharomyces boulardii, to prevent and treat various diarrhea and intestinal diseases. However, case reports on the side effects of a wide range of serious infections for the elderly, immunocompromised and critically ill patients after treatment with the S. cerevisiae have been increasing in recent years. The existing diagnose methods of the invasive S. cerevisiae infections in clinical, especially, the key step of the method-cell isolation, is time-consuming that always miss timey diagnose and early prevention. Here, we propose a new automatic micromanipulation method to label-free rapid isolation of S. cerevisiae based on the optically-induced dielectrophoresis (ODEP) technology, combining with image processing and recognition. S. cerevisiae is firstly identified by the image recognition method and then, automatically captured and moved to the target location by designing optical patterns. The results indicate the method can flexibly and automatically manipulate multiple S. cerevisiae cells simultaneously, such as, arranging S. cerevisiae cells, moving an array of the cells at any directions, aggregating the cells, and separating S. cerevisiae from the solution mixed with impurities. This work represents a step toward the use of automatic micromanipulation of ODEP technology to automatically and rapidly isolate S. cerevisiae for the detection of the invasive S. cerevisiae infections.

Cryopreservation of sperm before gonadotoxic treatment at the University Hospital Brno in the years 1995-2020

Sperm cryopreservation before gonadotoxic treatment is the basic and mos teffective method of preserving reproduction, which can be used during adolescence. The communication summarizes 26 years of experience in the operation of an oncological sperm bank, analyzes spermiograms of oncological patients, assesses the relationship between sperm pathology and diagnosis, and determines the number of deaths and the use of frozen sperm. During the existence of CAR 01 (assisted reproduction center), more than 50,000 spermiograms were performed. From January 1995 to December 2020, a total of 24,729 men were examined within the sperm bank, of which 1,448 (5.9%) had an oncological diagnosis. The spermiograms were evaluated according to current WHO (World Health Organization) manuals. Cryopreservation of sperm has undergone a major development. The rules for the storage of frozen cells have been laid down by Act No. 296/2008 Coll. since 2008. In 2019, the methodology „Cryopreservation of reproductive cells and tissues in patients before cancer treatment“ was updated. In all cases, the standard thawing technique was used. The sperms were processed by the swim-up method. As part of the treatment with assisted reproduction methods, oocytes were fertilized by the ICSI (intracytoplasmatic sperm injection) micromanipulation technique. Out of 1,448 examined spermiograms in men with oncological diagnoses, testicular cancer was present in 43.7% of patients and malignant diseases of lymphatic and hematopoietic tissue were found in 24.1%, of which 70,1% included Hodgkin‘s lymphomas and 29,9% were non-Hodgkin‘s lymphomas. Leukemia was found in 7.9%, bone and cartilage cancers in 6.8%. The age of the clients of the whole group ranged from 13 to 64 years (27.2 ± 6.8 years). A total of 38.3% of men had normozoospermia, 54.2% of spermiograms showed pathological findings in 1 to 3 evaluated parameters and 7.5% of patients had azoospermia. Severe asthenozoospermia (mobility ≤ 10%) was detected in 57.2% of men and severe oligozoospermia (concentration ≤ 1 × 106 mm3) in 22.3% of patients. The lowest values of the spermiogram were found in men with testicular cancer; the best values were seen in CNS (central nervous system) cancers. The cryopreservation of sperm was performed in 1,340 cases (92.5%). So far, a total of 160 men (11.9%) have used frozen sperm, of which 6.2% in our center. In these 83 cases, the ICSI technique was always used, 38 clinical pregnancies (45.8%) and 32 births were achieved. We have registered 424 completed storages of semen (31.6%), of which 148 (11.0% of all oncology patients) were made due to death and the others at patients’ request. Using the sperm of the dead is a specific issue. In cancer patients, sperm pathologies occur in high percentage. The lowest spermiogram values were found in men with testicular cancer. It is necessary to take into account long-term storage and fertilization by micromanipulation methods. The number of men who die is significantly higher than the number of those who use sperm to treat infertility. Cryopreservation of sperm should be offered to each patient prior to the therapy leading to the destruction of spermatogenesis.

Mechanophotonics-Mechanical Micromanipulation of Single-Crystals toward Organic Photonic Integrated Circuits.

The advent of molecular crystals as "smart" nanophotonic components namely, organic waveguides, resonators, lasers, and modulators are drawing wider attention of solid-state materials scientists and microspectroscopists. Crystals are usually rigid, and undeniably developing next-level crystalline organic photonic circuits of complex geometries demands using mechanically flexible crystals. The mechanical shaping of flexible crystals necessitates applying challenging micromanipulation methods. The rise of atomic force microscopy as a mechanical micromanipulation tool has increased the scope of mechanophotonics and subsequently, crystal-based microscale organic photonic integrated circuits (OPICs). The unusual higher adhesive energy of the flexible crystals to the surface than that of crystal shape regaining energy enables carving intricate crystal geometries using micromanipulation. This perspective reviews the progress made in a key research area developed by my research group, namely mechanophotonics-a discipline that uses mechanical micromanipulation of single-crystal optical components, to advance nanophotonics. The precise fabrication of photonic components and OPICs from both rigid and flexible microcrystal via AFM mechanical operations namely, moving, lifting, cutting, slicing, bending, and transferring of crystals are presented. The ability of OPICs to guide, split, couple, and modulate visible electromagnetic radiation using passive, active, and energy transfer mechanism are discussed as well with recent literature examples.

A microrobotic platform actuated by thermocapillary flows for manipulation at the air-water interface.

Future developments in micromanufacturing will require advances in micromanipulation tools. Several robotic micromanipulation methods have been developed to position micro-objects mostly in air and in liquids. The air-water interface is a third medium where objects can be manipulated, offering a good compromise between the two previously mentioned ones. Objects at the interface are not subjected to stick-slip due to dry friction in air and profit from a reduced drag compared with those in water. Here, we present the ThermoBot, a microrobotic platform dedicated to the manipulation of objects placed at the air-water interface. For actuation, ThermoBot uses a laser-induced thermocapillary flow, which arises from the surface stress caused by the temperature gradient at the fluid interface. The actuated objects can reach velocities up to 10 times their body length per second without any on-board actuator. Moreover, the localized nature of the thermocapillary flow enables the simultaneous and independent control of multiple objects, thus paving the way for microassembly operations at the air-water interface. We demonstrate that our setup can be used to direct capillary-based self-assemblies at this interface. We illustrate the ThermoBot's capabilities through three examples: simultaneous control of up to four spheres, control of complex objects in both position and orientation, and directed self-assembly of multiple pieces.

Controlled rotation of micro-objects using acoustically driven microbubbles

Micromanipulation has significantly advanced both biomedical and industrial fields. However, there is still an urgent demand for controlled rotational manipulation at the microscale. Here, we report a noncontact rotational micromanipulation method using the acoustically driven microbubble contained in a micropipette. Acoustic vibration of the microbubble close to its resonant frequency was used to generate radiation force and microstreaming in the aqueous medium, allowing for trapping and rotating the micro-object. Simulation and particle visualization of the flow field clearly showed the microstreaming pattern induced by the oscillating microbubble. Experiments with different microbeads demonstrated the highly stable immobilization and rotation that related to the size and density of the microbead. By adjusting the frequency and voltage of the sinusoidal wave applied to the piezoelectric transducer, we demonstrated that the rotation frequency could be controlled over a broad range.

Single-Cell Analysis of BRAFV600E and NRASQ61R Mutation Status in Melanoma Cell Lines as Method Generation for Circulating Melanoma Cells.

Molecular testing of tumor biopsies allows for the identification of the key mutations driving a patient's cancer. However, this is limited to singular nodes and may not accurately reflect cancer heterogeneity. Circulating tumor cell (CTC) analyses offer a noninvasive method of interrogating the genomic profile of patient-derived tumor material. To date, molecular analysis of CTCs has relied on the characterization of bulk or pooled CTC lysates, limiting the detection of minor tumorigenic CTC subclones. Here, we show a workflow enabling BRAFV600E/NRASQ61R mutation detection from single cultured melanoma cells by combining micromanipulation and genomic material amplification methods. This workflow can be directly integrated into circulating tumor cell analysis applications.

Beam Shaping by a Magnetic Fluid Deformable Mirror With Curved Trajectory for Optical Tweezer System

This article describes a novel optical tweezer system which utilizes a magnetic fluid deformable mirror (MFDM) with a wavefront sensor (WFS) and controller to produce a curved Bessel beam for manipulating an optically trapped microparticle. The MFDM is proposed to control the wavefront phase of the laser beam since it offers the ability to produce a nearly perfect axicon in reflection. The working principle of the MFDM and its modeling and design processes are introduced. A decentralized control method is presented for the MFDM to generate the desired mirror surface shape, combing an axicon and an adjustable compensation phase profile that transforms the incident beam into a self-accelerating Bessel-like beam with curved trajectory. Using a prototype MFDM, an experimental optical tweezer system is set up to verify this optical micromanipulation method. The experimental results show the effectiveness of the proposed technique for the manipulation of optically trapped microparticles.