Manipulation of zebrafish's orientation using artificial cilia in a microchannel with actively adaptive wall design

Microfluidic Devices: A Tool for Nanoparticle Synthesis and Performance Evaluation

The use of nanoparticles (NPs) in nanomedicine holds great promise for the treatment of diseases for which conventional therapies present serious limitations. Additionally, NPs can drastically improve early diagnosis and follow-up of many disorders. However, to harness their full capabilities, they must be precisely designed, produced, and tested in relevant models. Microfluidic systems can simulate dynamic fluid flows, gradients, specific microenvironments, and multiorgan complexes, providing an efficient and cost-effective approach for both NPs synthesis and screening. Microfluidic technologies allow for the synthesis of NPs under controlled conditions, enhancing batch-to-batch reproducibility. Moreover, due to the versatility of microfluidic devices, it is possible to generate and customize endless platforms for rapid and efficient in vitro and in vivo screening of NPs' performance. Indeed, microfluidic devices show great potential as advanced systems for small organism manipulation and immobilization. In this review, first we summarize the major microfluidic platforms that allow for controlled NPs synthesis. Next, we will discuss the most innovative microfluidic platforms that enable mimicking in vitro environments as well as give insights into organism-on-a-chip and their promising application for NPs screening. We conclude this review with a critical assessment of the current challenges and possible future directions of microfluidic systems in NPs synthesis and screening to impact the field of nanomedicine.

Microfluidic Applications of Artificial Cilia: Recent Progress, Demonstration, and Future Perspectives

Artificial cilia-based microfluidics is a promising alternative in lab-on-a-chip applications which provides an efficient way to manipulate fluid flow in a microfluidic environment with high precision. Additionally, it can induce favorable local flows toward practical biomedical applications. The endowment of artificial cilia with their anatomy and capabilities such as mixing, pumping, transporting, and sensing lead to advance next-generation applications including precision medicine, digital nanofluidics, and lab-on-chip systems. This review summarizes the importance and significance of the artificial cilia, delineates the recent progress in artificial cilia-based microfluidics toward microfluidic application, and provides future perspectives. The presented knowledge and insights are envisaged to pave the way for innovative advances for the research communities in miniaturization.

The evaluation of zebrafish cardiovascular and behavioral functions through microfluidics

This study proposed a new experimental approach for the vascular and phenotype evaluation of the non-anesthetized zebrafish with representative imaging orientations for heart, pectoral fin beating, and vasculature views by means of the designed microfluidic device through inducing the optomotor response and hydrodynamic pressure control. In order to provide the visual cues for better positioning of zebrafish, computer-animated moving grids were generated by an in-house control interface which was powered by the larval optomotor response, in conjunction with the pressure suction control. The presented platform provided a comprehensive evaluation of internal circulation and the linked external behaviors of zebrafish in response to the cardiovascular parameter changes. The insights from these imaging sections was extended to identify the linkage between the cardiac parameters and behavioral endpoints. In addition, selected chemicals such as ethanol and caffeine were employed for the treatment of zebrafish. The obtained findings can be applicable for future investigation in behavioral drug screening serving as the forefront in psychopharmacological and cognition research.

Comprehensive Hydrodynamic Investigation of Zebrafish Tail Beats in a Microfluidic Device with a Shape Memory Alloy

The zebrafish is acknowledged as a reliable species of choices for biomechanical-related investigations. The definite quantification of the hydrodynamic flow physics caused by behavioral patterns, particularly in the zebrafish tail beat, is critical for a comprehensive understanding of food toxicity in this species, and it can be further interpreted for possible human responses. The zebrafish’s body size and swimming speed place it in the intermediate flow regime, where both viscous and inertial forces play significant roles in the fluid–structure interaction. This pilot work highlighted the design and development of a novel microfluidic device coupled with a shape memory alloy (SMA) actuator to immobilize the zebrafish within the observation region for hydrodynamic quantification of the tail-beating behavioral responses, which may be induced by the overdose of food additive exposure. This study significantly examined behavioral patterns of the zebrafish in early developmental stages, which, in turn, generated vortex circulation. The presented findings on the behavioral responses of the zebrafish through the hydrodynamic analysis provided a golden protocol to assess the zebrafish as an animal model for new drug discovery and development.

A non-invasive acoustic-trapping of zebrafish microfluidics

Zebrafish is an emerging alternative model in behavioral and neurological studies for pharmaceutical applications. However, little is known regarding the effects of noise exposure on laboratory-grown zebrafish. Accordingly, this study commenced by exposing zebrafish embryos to loud background noise (≥200 Hz, 80 ± 10 dB) for five days in a microfluidic environment. The noise exposure was found to affect the larvae hatching rate, larvae length, and swimming performance. A microfluidic platform was then developed for the sorting/trapping of hatched zebrafish larvae using a non-invasive method based on light cues and acoustic actuation. The experimental results showed that the proposed method enabled zebrafish larvae to be transported and sorted into specific chambers of the microchannel network in the desired time frame. The proposed non-invasive trapping method thus has potentially profound applications in drug screening.

Microfluidic Transportation Control of Larval Zebrafish through Optomotor Regulations under a Pressure-Driven Flow

To perform zebrafish larvae-related experiments within a microfluidic environment, the larvae need to be anesthetized and subsequently transported into respective test sections through mechanical or manual means. However, anesthetization tends to affect larval sensory perceptions, hindering their natural behaviors. Taking into account that juvenile larvae move naturally within their environment by accessing visual as well as hydromechanical cues, this work proposes an experimental framework to transport nonanesthetized larvae within a microfluidic environment by harmonically tuning both of the aforementioned cues. To provide visual cues, computer-animated moving gratings were provided through an in-house-developed control interface that drove the larval optomotor response. In the meantime, to provide hydromechanical cues, the flow rate was tuned using a syringe pump that affected the zebrafish larvae’s lateral line movement. The results obtained (corresponding to different test conditions) suggest that the magnitude of both modalities plays a crucial role in larval transportation and orientation control. For instance, with a flow rate tuning of 0.1 mL/min along with grating parameters of 1 Hz temporal frequency, the average transportation time for larvae that were 5 days postfertilization was recorded at 1.29 ± 0.49 s, which was approximately three times faster than the transportation time required only in the presence of hydromechanical cues.

A noninvasive light driven technique integrated microfluidics for zebrafish larvae transportation

Transferring the zebrafish larvae on an imaging platform has long been performed manually by the use of forceps or through mechanical pumping. These methods induce detrimental damages to the fragile bodies of zebrafish larvae during the transportation. To address this issue, in this work we are devising a light driven technique to transport zebrafish larvae within a microfluidic environment. In particular, an optomotor behavioral response of the zebrafish larvae was controlled through the computer animated moving gratings for their transportation within a microfluidics chamber. It was observed that with an optimum grating frequency of 1.5 Hz and a grating width ratio of 1:1, a 5 days-post fertilization zebrafish larva can be transported within minimum and maximum time periods of 0.63 and 2.49 s, respectively. This proposed technique can be utilized towards multi-automatic transportation of zebrafish larvae within the microfluidic environment as well as the zebrafish core facility.

Visual Servoed Three-Dimensional Rotation Control in Zebrafish Larva Heart Microinjection System

OBJECTIVE

Zebrafish larva heart microinjection is a widely used technique in cardiac disease study. Compared with intensively researched rotation control of spherical or nearly spherical targets with clear structures, such as cells and embryos, 3-D rotation control of zebrafish larva demands new techniques due to its nontransparent structures and irregular outlines.

METHODS

In this paper, we present a vision-servo system to automate the rotation process of zebrafish larva body. A switched control strategy is adopted to rotate zebrafish larva about the optical axis by using two micropipettes. Precisely rolling about larva body is performed, which involves a custom-designed rotational micromanipulator. A vision detection and online tracking algorithm is also developed to meet the requirement of visual servoing. With designed rotation control strategy, zebrafish larva heart can be adjusted to a desired orientation, which is often towards the injection pipette tip.

RESULTS

Experimental results show that the designed system is capable of achieving high success rate of 94% about -axis rotation and 100% about -axis with 50 trails. The system also performs an average speed of 44 s/larva with a satisfied rotation accuracy of 0.5 in the horizontal plane and 2.5 about its roll axis.

CONCLUSION

The proposed strategy is effective in flexibly manipulating larvae in 3-D.

SIGNIFICANCE

The developed 3-D rotation control scheme is able to be applied to injection of various organs in zebrafish larva body for different experimental requirements.