Publications by authors named "Aaron Ohta"

Reconfigurable intelligent surfaces (RISs) have the potential to improve wireless communication links by dynamically redirecting signals to dead spots. Although a reconfigurable surface is best suited for environments in which the reflected signal must be dynamically steered, there are cases where a static, non-reconfigurable anomalous reflective metasurface can suffice. In this work, spray-coated liquid metal is used to rapidly prototype an anomalous reflective metasurface.

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Purpose: This retrospective observational study compares how different classes of blastocyst genotypes from egg donor cycles differentially blastulate and expand using a standard assay.

Methods: Quantitative measurements of expansion utilized a customized neural network that segments all sequential time-lapse images during the first 10 h of expansion.

Results: Analyses were performed using two developmental time perspectives using time-lapse imaging.

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Controllable deformation of liquid metal by electrocapillary actuation (ECA) is empirically characterized in fluidic channels at the sub-millimeter-length scale. In 100-µm-deep channels of varying widths, the Galinstan liquid metal could move at velocities of more than 40 mm/s. The liquid metal could extend more than 2.

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Research Question: Can artificial intelligence (AI) discriminate a blastocyst's cellular area from unedited time-lapse image files using semantic segmentation and a deep learning optimized U-Net architecture for use in selecting single blastocysts for transfer?

Design: This platform was retrospectively applied to time-lapse files from 101 sequentially transferred single blastocysts that were prospectively selected for transfer by their highest expansion ranking within cohorts using a 10 h expansion assay rather than standard grading.

Results: The AI platform provides expansion curves and raw data files to classify and compare blastocyst phenotypes within both cohorts and populations. Of 35 sequential unbiopsied single blastocyst transfers, 23 (65.

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In recent decades, the integration of microfluidic devices and multiple actuation technologies at the microscale has greatly contributed to the progress of related fields. In particular, microbubbles are playing an increasingly important role in microfluidics because of their unique characteristics that lead to specific responses to different energy sources and gas-liquid interactions. Many effective and functional bubble-based micromanipulation strategies have been developed and improved, enabling various non-invasive, selective, and precise operations at the microscale.

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Advancements in flexible circuit interconnects are critical for widespread adoption of flexible electronics. Non-toxic liquid-metals offer a viable solution for flexible electrodes due to deformability and low bulk resistivity. However, fabrication processes utilizing liquid-metals suffer from high complexity, low throughput, and significant production cost.

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Localized single cells can be lysed precisely and selectively using microbubbles optothermally generated by microsecond laser pulses. The shear stress from the microstreaming surrounding laser-induced microbubbles and direct contact with the surface of expanding bubbles cause the rupture of targeted cell membranes. High-resolution single-cell lysis is demonstrated: cells adjacent to targeted cells are not lysed.

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Accurate control and precise positioning of opto-thermocapillary flow-addressed bubble microrobots are necessary for micromanipulation. In addition, micromanipulation using the simultaneous actuation of multiple microrobots requires a robust control system to enable independent motion. This paper demonstrates a hybrid closed-loop vision-assisted control system capable of actuating multiple microrobots simultaneously and positioning them at precise locations relative to micro-objects under manipulation.

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Microfabricated devices and systems capable of micromanipulation are well-suited for the manipulation of cells.[..

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Micromanipulation for applications in areas such as tissue engineering can require mesoscale structures to be assembled with microscale resolution. One method for achieving such manipulation is the parallel actuation of many microrobots in parallel. However, current microrobot systems lack the independent actuation of many entities in parallel.

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Presented here is a method for actuating a gallium-based liquid-metal alloy without the need for an external power supply. Liquid metal is used as an anode to drive a complementary oxygen reduction reaction, resulting in the spontaneous growth of hydrophilic gallium oxide on the liquid-metal surface, which induces flow of the liquid metal into a channel. The extent and duration of the actuation are controllable throughout the process, and the induced flow is both reversible and repeatable.

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Opto-thermocapillary flow-addressed bubble (OFB) microrobots are a potential tool for the efficient transportation of micro-objects. This microrobot system uses light patterns to generate thermal gradients within a liquid medium, creating thermocapillary forces that actuate the bubble microrobots. An interactive control system that includes scanning mirrors and a touchscreen interface was developed to address up to ten OFB microrobots.

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Payloads including FITC-Dextran dye and plasmids were delivered into NIH/3T3 fibroblasts using microbubbles produced by microsecond laser pulses to induce pores in the cell membranes. Two different operational modes were used to achieve molecular delivery. Smaller molecules, such as the FITC-Dextran dye, were delivered via a scanning-laser mode.

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Laser-induced microbubbles were used to porate the cell membranes of localized single NIH/3T3 fibroblasts. Microsecond laser pulses were focused on an optically absorbent substrate, creating a vapour microbubble that oscillated in size at the laser focal point in a fluidic chamber. The shear stress accompanying the bubble size oscillation was able to porate nearby cells.

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Microrobots made of light-absorbing hydrogel material were actuated by optically induced thermocapillary flow and move at up to 700 µm/s. The micro-assembly capabilities of the microrobots were demonstrated by assembling polystyrene beads and yeast cells into various patterns on standard glass microscope slides. Two microrobots operating independently in parallel were also used to assemble micro-hydrogel structures.

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Molecular delivery into localized NIH/3T3 cells was achieved with microbubbles produced by laser pulses focused on an optically absorbent substrate. The laser-induced bubble expansion and contraction resulted in cell poration. The microbubbles are localized at the laser focal point, so molecular delivery can be directed at specific localized cells.

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An opto-thermocapillary micromanipulator (OTMm) capable of single-cell manipulation and patterning is presented here. The OTMm uses a near-infrared laser focused on an ITO substrate to induce thermocapillary convection that can trap and transport living cells with forces of up to 40 pN. The OTMm complements other cell-manipulation technologies, such as optical tweezers and dielectrophoresis, as it is less dependent upon the optical and electrical properties of the working environment, and can function in many types of cell culture media.

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A novel hydrogel microrobot made of poly(ethylene glycol) diacrylate (PEGDA) is reported. This disk-shaped microrobot is optothermally actuated by laser-induced bubbles. A pulsed laser is used to smoothly actuate an 80-μm-diameter bubble microrobot at up to 320 μm s(-1).

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A novel 3D cell culture system was developed and tested. The cell culture device consists of a microfluidic chamber on an optically absorbing substrate. Cells are suspended in a thermoresponsive hydrogel solution, and optical patterns are utilized to heat the solution, producing localized hydrogel formation around cells of interest.

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A microfluidic device was designed having the ability to continuously produce monodisperse microcapsules with controlled cell loading. The design included stages of inertial focusing, droplet generation, and photopolymerization. Prototype microfluidic devices were fabricated in polydimethylsiloxane (PDMS) to demonstrate each stage using poly(ethylene-glycol)-diacrylate (PEGDA) as the encapsulating material and oil as the droplet-containing medium, creating a water-in-oil emulsion.

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Purpose: For intracytoplasmic sperm injection in the absence of sperm motility it can be virtually impossible to distinguish viable from nonviable sperm. A reliable means to identify viable nonmotile sperm is needed and would likely improve the intracytoplasmic sperm injection success rate. Optoelectronic tweezers are a new technology that uses light induced dielectrophoresis fields to distinguish individual live cells from dead cells.

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Optoelectronic tweezers was used to manipulate human spermatozoa to determine whether their response to OET predicts sperm viability among non-motile sperm. We review the electro-physical basis for how live and dead human spermatozoa respond to OET. The maximal velocity that non-motile spermatozoa could be induced to move by attraction or repulsion to a moving OET field was measured.

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Optoelectronic tweezers (OET), based on light-induced dielectrophoresis, has been shown as a versatile tool for parallel manipulation of micro-particles and cells (P. Y. Chiou, A.

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Optoelectronic tweezers enables parallel manipulation of individual single cells using optical addressing and optically induced dielectrophoretic force. This provides a useful platform for performing a variety of biological functions, such as cell manipulation, cell sorting, and cell electroporation. However, in order to obtain more reliable cellular manipulation, especially of adherent mammalian cells, antifouling coatings need to be used to avoid non-specific cell adherence.

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We introduce NanoPen, a novel technique for low optical power intensity, flexible, real-time reconfigurable, and large-scale light-actuated patterning of single or multiple nanoparticles, such as metallic spherical nanocrystals, and one-dimensional nanostructures, such as carbon nanotubes. NanoPen is capable of dynamically patterning nanoparticles over an area of thousands of square micrometers with light intensities <10 W/cm(2) (using a commercial projector) within seconds. Various arbitrary nanoparticle patterns and arrays (including a 10 x 10 array covering a 0.

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