A Method of Three-Dimensional Micro-Rotational Flow Generation for Biological Applications

Selective Acoustic Trapping, Translating, Rotating, and Orienting of Organism From Heterogeneous Mixture

Selective contactless manipulation of organisms with intrinsic mobility from heterogeneous mixture is essential for biomedical engineering and microbiology. Acoustic manipulation, compared to its optical, magnetic, and electrostatic counterparts, provides superior bio-compatibility and additive-free properties. In this study, we present an acoustic manipulation system capable of selectively trapping, translating, rotating, and orienting individual organisms from in-Petri dish organism mixture using a phased transducer array and microscope, by dynamically steering the acoustic field. Specifically, using brine shrimp and zebrafish populations as example, the to-be-manipulated organisms with different sizes or morphologies can be manually designated by the user in microscopic image and interactively localized. Thereafter, the selected organisms can be automatically trapped from the heterogeneous mixture using a multiple focal point-based acoustic field steering method. Finally, the trapped organisms can be translated, rotated, and oriented in regard to the user's distinct manipulation objectives in instant response. In different tasks, closed-loop positioning and real-time motion planning control are performed, highlighting the innovation in terms of automation and accuracy of our manipulation technique. The results demonstrate that our acoustic manipulation system and acoustic field steering method enable selective, stable, precision, real-time, and in-Petri dish manipulation of organisms from heterogeneous mixture.

Ultrasonic Manipulation of Hydrodynamically Driven Microparticles in Vessel Bifurcation: Simulation, Optimization, Experimental Validation, and Potential for Targeted Drug Delivery

Microrobots driven by multiple external power sources have emerged as promising tools for targeted drug and stem cell delivery in tissue regeneration. However, navigating and imaging these devices within a complex colloidal vascular system at a clinical scale is challenging. Ultrasonic actuators have gained interest in the field of non-contact manipulation of micromachines due to their label-free biocompatible nature and safe operation history. This research presents experimentally validated simulation results of ultrasonic actuation using a novel ultrasonic transducer array with a hemispherical arrangement that generates active traveling waves with phase modulation. Blood flow is used as a carrier force while the direction and path are controlled by blocking undesirable paths using a highly focused acoustic field. In the experiments, the microrobot cluster was able to follow a predefined trajectory and reach the target. The microrobot size, maximum radiation pressure, and focus position were optimized for certain blood flow conditions. The outcomes suggest that this acoustic manipulation module has potential applications in targeted tumor therapy.

Acoustically Driven Cell-Based Microrobots for Targeted Tumor Therapy

Targeted drug delivery using microrobots manipulated by an external actuator has significant potential to be a practical approach for wireless delivery of therapeutic agents to the targeted tumor. This work aimed to develop a novel acoustic manipulation system and macrophage-based microrobots (Macbots) for a study in targeted tumor therapy. The Macbots containing superparamagnetic iron oxide nanoparticles (SPIONs) can serve as drug carriers. Under an acoustic field, a microrobot cluster of the Macbots is manipulated by following a predefined trajectory and can reach the target with a different contact angle. As a fundamental validation, we investigated an in vitro experiment for targeted tumor therapy. The microrobot cluster could be manipulated to any point in the 4 × 4 × 4 mm region of interest with a position error of less than 300 μm. Furthermore, the microrobot could rotate in the O-XY plane with an angle step of 45 degrees without limitation of total angle. Finally, we verified that the Macbots could penetrate a 3D tumor spheroid that mimics an in vivo solid tumor. The outcome of this study suggests that the Macbots manipulated by acoustic actuators have potential applications for targeted tumor therapy.

Dual-fiber microfluidic chip for multimodal manipulation of single cells

On-chip single-cell manipulation is imperative in cell biology and it is desirable for a microfluidic chip to have multimodal manipulation capability. Here, we embedded two counter-propagating optical fibers into the microfluidic chip and configured their relative position in space to produce different misalignments. By doing so, we demonstrated multimodal manipulation of single cells, including capture, stretching, translation, orbital revolution, and spin rotation. The rotational manipulation can be in-plane or out-of-plane, providing flexibility and capability to observe the cells from different angles. Based on out-of-plane rotation, we performed a 3D reconstruction of cell morphology and extracted its five geometric parameters as biophysical features. We envision that this type of microfluidic chip configured with dual optical fibers can be helpful in manipulating cells as the upstream process of single-cell analysis.

Automatic System for the Blastocyst Embryo Manipulation and Rotation

Cell manipulation plays a vital role in the success rate and efficiency of the cell microsurgical operations, including biopsy of cell internal organelles such as the embryo biopsy, in which the embryo is manipulated and reoriented safely to a predefined desired position and orientation. In this paper, a simplified approach for the blastocyst embryo reorientation is proposed. It utilizes conventional tools and techniques currently in use in manual approaches in research labs and In Vitro Fertilization clinics, and controls the process using a vision feedback system. An experimental setup is developed to verify the dynamic behavior of the proposed approach, in which a stationary holding micropipette is used to hold the embryo, which is then rotated in two coordinate directions through friction contact with a moving substrate, in our case a glass microscope slide. The embryo rotates on the holding micropipette tip, due to the relatively low friction of this contact. A computer vision algorithm is used to estimate the embryo orientation coordinates, and use this information as a feedback signal to a simple proportional controller to control the embryo rotation angle. Experimental results demonstrate that the system is capable of cell rotation in two independent coordinates, suitable for embryo microsurgical task execution.

Development of a High Flow Rate 3-D Electroosmotic Flow Pump

A low voltage 3D parallel electroosmotic flow (EOF) pump composed of two electrode layers and a fluid layer is proposed in this work. The fluid layer contains twenty parallel fluid channels and is set at the middle of the two electrode layers. The distance between fluid and electrode channels was controlled to be under 45 μm, to reduce the driving voltage. Room temperature liquid metal was directly injected into the electrode channels by syringe to form non-contact electrodes. Deionized (DI) water with fluorescent particles was used to test the pumping performance of this EOF pump. According to the experimental results, a flow rate of 5.69 nL/min was reached at a driving voltage of 2 V. The size of this pump is small, and it shows a great potential for implanted applications. This structure could be easily expanded for more parallel fluid channels and larger flow rate.

Micro/Nano Devices for Chemical Analysis

Since the concept of micro total analysis systems (µ-TAS) has been advocated, various kinds of micro/nano devices have been developed by researchers in many fields, such as in chemistry, chemical engineering, mechanical engineering, electric engineering, biology, and medicine, among others.[...].