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Abstract Modern biomedical research and preclinical pharmaceutical development rely heavily on the phenotyping of small vertebrate models for various diseases prior to human testing. In this article, we demonstrate an acoustofluidic rotational tweezing platform that enables contactless, high-speed, 3D multispectral imaging and digital reconstruction of zebrafish larvae for quantitative phenotypic analysis. The acoustic-induced polarized vortex streaming achieves contactless and rapid (~1 s/rotation) rotation of zebrafish larvae. This enables multispectral imaging of the zebrafish body and internal organs from different viewing perspectives. Moreover, we develop a 3D reconstruction pipeline that yields accurate 3D models based on the multi-view images for quantitative evaluation of basic morphological characteristics and advanced combinations of metrics. With its contactless nature and advantages in speed and automation, our acoustofluidic rotational tweezing system has the potential to be a valuable asset in numerous fields, especially for developmental biology, small molecule screening in biochemistry, and pre-clinical drug development in pharmacology.
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Intelligent acoustofluidics enabled mini-bioreactors for human brain organoids
Acoustofluidics, by combining acoustics and microfluidics, provides a unique means to manipulate cells and liquids for broad applications in biomedical sciences and translational medicine. However, it is challenging to standardize and maintain excellent performance of current acoustofluidic devices and systems due to a multiplicity of factors including device-to-device variation, manual operation, environmental factors, sample variability, etc. Herein, to address these challenges, we propose “intelligent acoustofluidics” – an automated system that involves acoustofluidic device design, sensor fusion, and intelligent controller integration. As a proof-of-concept, we developed intelligent acoustofluidics based mini-bioreactors for human brain organoid culture. Our mini-bioreactors consist of three components: (1) rotors for contact-free rotation via an acoustic spiral phase vortex approach, (2) a camera for real-time tracking of rotational actions, and (3) a reinforcement learning-based controller for closed-loop regulation of rotational manipulation. After training the reinforcement learning-based controller in simulation and experimental environments, our mini-bioreactors can achieve the automated rotation of rotors in well-plates. Importantly, our mini-bioreactors can enable excellent control over rotational mode, direction, and speed of rotors, regardless of fluctuations of rotor weight, liquid volume, and operating temperature. Moreover, we demonstrated our mini-bioreactors can stably maintain the rotational speed of organoids during long-term culture, and enhance neural differentiation and uniformity of organoids. Comparing with current acoustofluidics, our intelligent system has a superior performance in terms of automation, robustness, and accuracy, highlighting the potential of novel intelligent systems in microfluidic experimentation.
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- Award ID(s):
- 1909509
- PAR ID:
- 10283705
- Date Published:
- Journal Name:
- Lab on a Chip
- Volume:
- 21
- Issue:
- 11
- ISSN:
- 1473-0197
- Page Range / eLocation ID:
- 2194 to 2205
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Acoustic microfluidics has emerged as a versatile solution for particle manipulation in medicine and biology. However, current technologies are largely confined to specialized research laboratories. The translation of acoustofluidics from research to clinical and industrial settings requires improved consistency and repeatability across different platforms. Performance comparisons will require straightforward experimental assessment tools that are not yet available. We introduce a method for characterizing acoustofluidic devices in real-time by exploiting the capacity of swimming microorganisms to respond to changes in their environment. The unicellular alga, Chlamydomonas reinhardtii , is used as an active probe to visualize the evolving acoustic pressure field within microfluidic channels and chambers. In contrast to more familiar mammalian cells, C. reinhardtii are simple to prepare and maintain, and exhibit a relatively uniform size distribution that more closely resembles calibration particles; however, unlike passive particles, these motile cells naturally fill complex chamber geometries and redistribute when the acoustic field changes or is turned off. In this way, C. reinhardtii cells offer greater flexibility than conventional polymer or glass calibration beads for in situ determination of device operating characteristics. To illustrate the technique, the varying spatial density and distribution of swimming cells are correlated to the acoustic potential to automatically locate device resonances within a specified frequency range. Peaks in the correlation coefficient of successive images not only identify the resonant frequencies for various geometries, but the peak shape can be related to the relative strength of the resonances. Qualitative mapping of the acoustic field strength with increasing voltage amplitude is also shown. Thus, we demonstrate that dynamically responsive C. reinhardtii enable real-time measurement and continuous monitoring of acoustofluidic device performance.more » « less
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Controllable, precise, and stable rotational manipulation of model organisms is valuable in many biomedical, bioengineering, and biophysics applications. We present an acoustofluidic chip capable of rotating Caenorhabditis elegans ( C. elegans ) in both static and continuous flow in a controllable manner. Rotational manipulation was achieved by exposing C. elegans to a surface acoustic wave (SAW) field that generated a vortex distribution inside a microchannel. By selectively activating interdigital transducers, we achieved bidirectional rotation of C. elegans , namely counterclockwise and clockwise, with on-demand switching of rotation direction in a single chip. In addition to continuous rotation, we also rotated C. elegans in a step-wise fashion with a step angle as small as 4° by pulsing the signal duration of SAW from a continuous signal to a pulsed signal down to 1.5 ms. Using this device, we have clearly imaged the dopaminergic neurons of C. elegans with pdat-1:GFP expression, as well as the vulval muscles and muscle fibers of the worm with myo-3::GFP fusion protein expression in different orientations and three dimensions. These achievements are difficult to realize through conventional ( i.e. , non-confocal) microscopy. The SAW manipulations did not detectably affect the health of the model organisms. With its precision, controllability, and simplicity in fabrication and operation, our acoustofluidic devices will be well-suited for model organism studies.more » « less
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Abstract The analysis of tissue cultures, particularly brain organoids, requires a sophisticated integration and coordination of multiple technologies for monitoring and measuring. We have developed an automated research platform enabling independent devices to achieve collaborative objectives for feedback-driven cell culture studies. Our approach enables continuous, communicative, non-invasive interactions within an Internet of Things (IoT) architecture among various sensing and actuation devices, achieving precisely timed control ofin vitrobiological experiments. The framework integrates microfluidics, electrophysiology, and imaging devices to maintain cerebral cortex organoids while measuring their neuronal activity. The organoids are cultured in custom, 3D-printed chambers affixed to commercial microelectrode arrays. Periodic feeding is achieved using programmable microfluidic pumps. We developed a computer vision fluid volume estimator used as feedback to rectify deviations in microfluidic perfusion during media feeding/aspiration cycles. We validated the system with a set of 7-day studies of mouse cerebral cortex organoids, comparing manual and automated protocols. The automated protocols were validated in maintaining robust neural activity throughout the experiment. The automated system enabled hourly electrophysiology recordings for the 7-day studies. Median neural unit firing rates increased for every sample and dynamic patterns of organoid firing rates were revealed by high-frequency recordings. Surprisingly, feeding did not affect firing rate. Furthermore, performing media exchange during a recording showed no acute effects on firing rate, enabling the use of this automated platform for reagent screening studies.more » « less
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Theoretical modeling of acoustofluidic systems faces extreme challenges as the thickness of the thermoviscous boundary layer is very small compared to the microscale fluid dimensions. The classical pressure acoustic model overcomes these difficulties and is extensively used in simulating three-dimensional (3D) or large two-dimensional (2D) acoustofluidic systems. However, this model cannot be applied to thermoviscous acoustofluidics, as it does not consider energy conservation. Modeling thermoviscous acoustofluidic systems is, therefore, difficult and restricted to small 2D systems only. Here, we have developed a thermo-pressure acoustic model that can effectively simulate thermoviscous acoustofluidic systems. The model has been validated with the full model by performing numerical simulations for a small 2D acoustofluidic system for which capturing the acoustic boundary layer effect is feasible using the full model. After successful validation, we demonstrate that the thermo-pressure acoustic model can also be applied to studying 3D acoustofluidic systems.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d1lc00145k
