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X offset and Y offset of the center of a solder bead with respect to the center of the circular trap with a diameter of (a) 60 lm, (b) 80 lm, (c) 100 lm, (d) 120 lm, (e) 140 lm, and (f) 180 lm; (g) positioning accuracy of the solder bead in the X direction for traps with different sizes; (h) positioning accuracy of the solder bead in the Y direction for traps with different sizes; and (i) average positioning accuracy of the solder bead for traps with different sizes.
Source publication
In this work, we analyze the use of optoelectronic tweezers (OETs) to manipulate 45 μm diameter Sn62 Pb 36 Ag 2 solder beads with light-induced dielectrophoresis force and we demonstrate high positioning accuracy. It was found that the positional deviation of the solder beads increases with the increase of the trap size. To clarify the underlying m...
Contexts in source publication
Context 1
... the bead follows the trap perfectly as it moves, these offsets would be zero. Figures 3(a)-3(f) show the X offset and Y offset of the centre of a solder bead with respect to the centre of a trap for traps with different sizes. As shown, both X and Y offsets of the solder bead generally increase with the increase of trap size, indicating that the sol- der bead is less well confined to the central region. ...
Context 2
... Equation (3), Aver deviation represents the average positioning deviation. Based on these equations, we can calculate the positioning deviation of a solder bead in X and Y directions and the average position deviation when the bead is positioned by traps with different sizes, as shown in Figures 3(g)-3(i). As shown, the positioning deviation of the solder bead increases linearly with the increase of the trap size, indicating the reduced capability of a larger trap to posi- tion the bead accurately. ...
Context 3
... normalizing the simulation results based on the measured peak DEP force, the shape of the simulation data matches up with the measured data very well and provides useful information of the trap profiles. To analyze the circu- lar region where the stiction force dominates, the data of the average position deviation shown in Figure 3(i) were used as the radius of the circular region for each trap. For this circu- lar region, the DEP force dominates outside it while the stic- tion force dominates inside it. ...
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Citations
... Nondestructive trapping and manipulation of micro-/nano-sized objects are of great interest in biotechnology, lab-on-a-chip, and various other applications. [1][2][3][4] Conventional optical tweezers, 5,6 plasmonic tweezers, 7,8 and dielectrophoresis (DEP) 9,10 based techniques have widely been used for such applications. 11 However, optoelectronic tweezers (OETs) 12 have become increasingly popular as they require less optical power than conventional optical trapping and can be more versatile than dielectrophoretic devices. ...
An optoelectronic tweezer (OET) device is presented that exhibits improved trapping resolution for a given optical spot size. The scheme utilizes a pair of patterned physical electrodes to produce an asymmetric electric field gradient. This, in turn, generates an azimuthal force component in addition to the conventional radial gradient force. Stable force equilibrium is achieved along a pair of antipodal points around the optical beam. Unlike conventional OETs where trapping can occur at any point around the beam perimeter, the proposed scheme improves the resolution by limiting trapping to two points. The working principle is analyzed by performing numerical analysis of the electromagnetic fields and corresponding forces. Experimental results are presented that show the trapping and manipulation of micro-particles using the proposed device.
... www.advancedsciencenews.com www.advintellsyst.com (DEP) (rather than the forces generated by direct photon momentum), OET systems typically exert a stronger manipulation force for a given intensity of light compared to OT. [136,188] The applications of OET include trapping, [189] bead positioning, [190] and manipulation and assembly of micro particles. [191] More Advanced Trapping techniques have emerged, which use machine learning technologies to automatically localize and trap microrobots in the OT. ...
Maturation of robotics research and advances in the miniaturization of machines have contributed to the development of microbots and enabled new technological possibilities and applications. Microbots have a wide range of applications, including the navigation of confined spaces, environmental monitoring, micro-assembly and manipulation of small objects, and in vivo micro-surgeries and drug delivery. Actuators are among the most critical components that define the performance of robots. A comprehensive review of the actuation mechanisms that have been employed in mobile microbots is provided, including piezoelectric, magnetic, electrostatic, thermal, acoustic, biological, chemical, and optical actuation, with a focus on the most recent development and methodologies.
... The former approach only allows the manipulation of objects within the field of view, while the later approach allows the manipulation of objects beyond the field of view. In addition, motorized positioning stage allows accurate control of the translational speed of the trapped object, [75][76][77] which is important to study the exerted manipulation force by the OET system. In some cases [ Fig. 3(a)], light patterns are projected onto the OET device from the top of the device, which shares the same objective lens for observation and brightfield illumination. ...
... Commercially-available DMD projector and liquid crystal display (LCD) projector are the commonly used light sources for an OET platform. [74][75][76][77][78][79][80][81][82] Self-built optical systems consisting of a DMD chip and a light source (e.g. LED, laser, and Hg lamp) have also be used for OET research. ...
... OET has also been used to manipulate a variety of microscale objects on the order of several microns to a few hundreds of microns, including dielectric/metallic microparticles, 44,45,50,[53][54][55][75][76][77]80,89,[91][92][93][94]96,[100][101][102][103]109,120,121,127,[133][134][135][136][137][138][139][140][141][142][143] oil/water droplets, 144-149 gas bubbles, 51 and electronic/photonic components. 47,77,110,127 For the OET research, the most commonly used microscale objects are polystyrene spherical microbeads, which have desirable shapes and dielectric properties to work in OET systems. ...
The rapid development of micromanipulation technologies has opened exciting new opportunities for the actuation, selection and assembly of a variety of non-biological and biological nano/micro-objects for applications ranging from microfabrication, cell analysis, tissue engineering, biochemical sensing, to nano/micro-machines. To date, a variety of precise, flexible and high-throughput manipulation techniques have been developed based on different physical fields. Among them, optoelectronic tweezers (OET) is a state-of-art technique that combines light stimuli with electric field together by leveraging the photoconductive effect of semiconductor materials. Herein, the behavior of micro-objects can be directly controlled by inducing the change of electric fields on demand in an optical manner. Relying on this light-induced electrokinetic effect, OET offers tremendous advantages in micromanipulation such as programmability, flexibility, versatility, high-throughput and ease of integration with other characterization systems, thus showing impressive performance compared to those of many other manipulation techniques. A lot of research on OET have been reported in recent years and the technology has developed rapidly in various fields of science and engineering. This work provides a comprehensive review of the OET technology, including its working mechanisms, experimental setups, applications in non-biological and biological scenarios, technology commercialization and future perspectives.
... Dielectrophoresis can be used to manipulate, transport, separate, and sort different types of particles based on the frequency-dependent relative polarizabilities of the particle and medium [9][10][11]. To date, the vast majority of DEP-based systems can be classified as electrode-based dielectrophoresis (eDEP), insulatorbased dielectrophoresis (iDEP) [12], and light induced DEP [13][14][15]. In iDEP chips, where the gradient of the electric field is formed by geometrical constrictions within insulating substrates instead of metallic microelectrodes, the electrodes are positioned remotely and do not contact the particles or cells directly. ...
Porous dielectric membranes that perform insulator-based dielectrophoresis or electroosmotic pumping are commonly used in microchip technologies. However, there are few fundamental studies on the electrokinetic flow patterns of single microparticles around a single micropore in a thin dielectric film. Such a study would provide fundamental insights into the electrokinetic phenomena around a micropore, with practical applications regarding the manipulation of single cells and microparticles by focused electric fields. We have fabricated a device around a silicon nitride film with a single micropore (2–4 µm in diameter) which has the ability to locally focus electric fields on the micropore. Single microscale polystyrene beads were used to study the electrokinetic flow patterns. A mathematical model was developed to support the experimental study and evaluate the electric field distribution, fluid motion, and bead trajectories. Good agreement was found between the mathematic model and the experimental data. We show that the combination of electroosmotic flow and dielectrophoretic force induced by direct current through a single micropore can be used to trap, agglomerate, and repel microparticles around a single micropore without an external pump. The scale of our system is practically relevant for the manipulation of single mammalian cells, and we anticipate that our single-micropore approach will be directly employable in applications ranging from fundamental single cell analyses to high-precision single cell electroporation or cell fusion.
... Optoelectronic tweezer (OET) is an optical micromanipulation technology that relies on optically induced-dielectrophoresis (ODEP) force for the control of micro-/nano-scale objects [1][2][3][4][5]. Based on light patterned electric fields, OET is capable of exerting pico-to-nano Newton manipulation forces [6,7], and is well suited for parallel and independent control of multiple objects [1,3,8,9]. Because of these outstanding micromanipulation capabilities, OET has been widely used to manipulate and assemble bio-analytes and molecules [10][11][12], cells of different species [13][14][15][16][17][18][19][20], nano-/microparticles [8,[21][22][23][24][25][26], electronic/ photonic components [27][28][29][30][31][32][33], and microrobots [9], thus offering a powerful scientific tool to investigate the microscopic world for physical, chemical, and biological studies. ...
... where η is the viscosity of the liquid, r is the radius of the bead, and ν is the velocity of the bead. Since gravity forces the bead to sit in proximity to the a-Si:H surface, Faxen's correction was applied to adjust the calculation of the viscous drag force and the DEP force [6,17,38]. For each doughnut ring thickness evaluated, the maximum moving velocity of the bead was measured by gradually increasing the speed of the motorized stage, observing the velocity at which the bead fell out of the trap (see Visualization 2, clip 4). ...
... To probe the phenomenon of reduced force found for thick doughnut rings and to clarify the physical mechanism for the observed experimental results, simulations were carried out in COMSOL Multiphysics using the AC/DC module (COMSOL Inc., Burlington, MA, accessed via license obtained through CMC Microsystems, Kingston, Canada) [6][7][8][9]. The model length (x axis) and height (y axis) were set to 500 μm and 150 μm, respectively. ...
Optoelectronic tweezer (OET) is a useful optical micromanipulation technology that has been demonstrated for various applications in electrical engineering and most notably cell selection for biomedical engineering. In this work, we studied the use of light patterns with different shapes and thicknesses to manipulate dielectric micro-particles with OET. It was demonstrated that the maximum velocities of the microparticles increase to a peak and then gradually decrease as the light pattern’s thickness increases. Numerical simulations were run to clarify the underlying physical mechanisms, and it was found that the observed phenomenon is due to the co-influence of horizontal and vertical dielectrophoresis forces related to the light pattern’s thickness. Further experiments were run on light patterns with different shapes and objects of different sizes and structures. The experimental results indicate that the physical mechanism elucidated in this research is an important one that applies to different light pattern shapes and different objects, which is useful for enabling users to optimize OET settings for future micro-manipulation applications.
... By projecting illuminated and dark regions onto the photoconductive substrate, lightactivated virtual electrodes can be formed in OET, which induce nonuniform electric fields producing DEP forces [42][43][44][45][46][47][48][49][50][51][52] . OET is capable of generation of forces on the order of nanoNetwons (10 −9 N) 53 , which permits the manipulation of objects with sizes >100 μm 54,55 . In addition, it is particularly straightforward to use OET for parallel manipulation [41][42][43][44][45] , simply by projecting movies of moving shapes into a microscope. ...
There is great interest in the development of micromotors which can convert energy to motion in sub-millimeter dimensions. Micromachines take the micromotor concept a step further, comprising complex systems in which multiple components work in concert to effectively realize complex mechanical tasks. Here we introduce light-driven micromotors and micromachines that rely on optoelectronic tweezers (OET). Using a circular micro-gear as a unit component, we demonstrate a range of new functionalities, including a touchless micro-feed-roller that allows the programming of precise three-dimensional particle trajectories, multi-component micro-gear trains that serve as torque- or velocity-amplifiers, and micro-rack-and-pinion systems that serve as microfluidic valves. These sophisticated systems suggest great potential for complex micromachines in the future, for application in microrobotics, micromanipulation, microfluidics, and beyond.
... By measuring the center-to-center distance at varying velocities, a profile of the DEP force experienced by a bead at different positions within the trap can be plotted, as shown by the markers in Figure 5c. We also investigated the achievable positioning accuracy, [47] which is important for assembly applications. Solder beads were repeatedly translated to randomized destinations between 30 and 500 µm away from their initial positions, and the difference between each bead's relative position in the trap before and after moving, the "post-translational offset" (PTO), was recorded. ...
Micromanipulation techniques that are capable of assembling nano/micromaterials into usable structures such as topographical micropatterns (TMPs) have proliferated rapidly in recent years, holding great promise in building artificial electronic and photonic microstructures. Here, a method is reported for forming TMPs based on optoelectronic tweezers in either “bottom-up” or “top-down” modes, combined with in situ photopolymerization to form permanent structures. This work demonstrates that the assembled/cured TMPs can be harvested and transferred to alternate substrates, and illustrates that how permanent conductive traces and capacitive circuits can be formed, paving the way toward applications in microelectronics. The integrated, optical assembly/preservation method described here is accessible, versatile, and applicable for a wide range of materials and structures, suggesting utility for myriad microassembly and microfabrication applications in the future.
... Optoelectronic tweezers (OETs) 6 were developed to address some of the limitations of conventional optical tweezers (COTs) 7 and electrode-based dielectrophoresis (DEP) schemes. Since then, OETs have been successfully used in many applications 1, 8,9 . As the demand for lab-on-a-chip (LOC) systems with particle manipulation capabilities increases, advances in OETs can be of significant interest 10,11 . ...
An optoelectronic tweezers (OETs) system employing a non-uniform background electric field is presented. In addition to optically induced electrodes, physical electrodes are incorporated into the design. The geometries of the physical electrodes are selected to create a background field with gradients along a specific axis. Due to the resulting background force, the proposed scheme traps particles along an axis around the rim of the optical spot. This is a resolution improvement over conventional OETs where particle trapping occurs uniformly around the spot. Numerical simulations of the device including conductivity, electric fields, and force profiles are presented. The trapping and manipulation of micro-particles using the device are experimentally demonstrated. The experiment verifies that trapping occurs along a specific axis of the optical beam.
... Rather than using conventional OT, we have chosen to use a related but distinct optical technique known as optoelectronic tweezers (OET) [12][13][14][15][16][17][18][19][20]. Because OET relies on light to trigger the application of dielectrophoresis (DEP) forces rather than relying on forces generated by direct photon momentum, OET systems typically exert a much stronger manipulation force for a given intensity of light compared with OT [21][22][23][24]. In addition, the light patterns used to control OET can be generated with consumer-grade optical projectors, making OET widely accessible and well suited for parallel manipulation [12,19]. ...
... Here, we report a new technique for design and manufacture of TMPs, relying on optoelectronic tweezers (OET). [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] The new method is a member of the wet cleanroom-free assembly techniques, but lacks many of the limitations indicated previously. In this report, we describe the use of the new technique to form TMPs from suspensions of polystyrene microbeads, metallic Topographical micropatterns (TMPs), or ordered arrays of 3D features on a flat surface, have become important for a wide range of applications. ...
