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1.
Microsc Res Tech ; 82(10): 1741-1747, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31295381

RESUMO

In this work a single glycerol-water mixture, determined to be most apt at 30% (wt/vol), was used to immobilize Drosophila samples as well as to create a liquid lens for smartphone magnification viewing. This provides the advantage of being able to observe immobilized insects directly in the field rather than in the laboratory. In order to avoid having bubbles in the liquid lens and immobilizing medium that hinder visibility, an approach was developed where a stable pendant drop is moved in tandem with the dispensing tip by gravity and stopped abruptly so that sufficient momentum is transferred to the drop for its dislodgement. With 30% glycerol-water (wt/vol) mixtures, applying a minimal stroke of 10 mm with longitudinal impact delivered a momentum of 0.1464 N/s that allowed transfer of a preselected liquid volume for the processes.


Assuntos
Drosophila/anatomia & histologia , Entomologia/instrumentação , Entomologia/métodos , Microscopia/instrumentação , Microscopia/métodos , Smartphone , Animais
2.
Mater Sci Eng C Mater Biol Appl ; 96: 599-605, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30606571

RESUMO

Superhydrophobic substrates facilitate low adhesion for biological liquid handling but are hampered by wetting state changes due to condensation. Here, meshed near-superhydrophobic substrates, that are easier to produce than two-tiered architecture substrates, are shown to provide good immunity to wetting state changes while imbuing high positional resistance to roll-off by tilting when tested with 5 and 10 µL volume drops (18° and 13° respectively) of human IgG antibodies in aqueous solution at both room temperature and 4 °C. Pneumatic actuation was applied to elicit horizontal drop movement over the near-SH surface without any fragmentation, wherein higher velocities can be achieved when smaller drops and higher air pressures are used (0.385 m/s at 33 mbar with the 5 µL drop). A non-contact mode of translating a protein drop towards a highly viscous oil-based adjuvant dispensed from a steel tip allowed for both drops to be combined and aspirated back up into the tip such that subsequent repeated cycles of pendant drop formation and upward aspiration allows for effective mixing to achieve a stable emulsion. The findings here advance the development of devices that enable improved antigen-adjuvant preparation by reducing the amount of reagents required and product losses from surface adsorption.


Assuntos
Interações Hidrofóbicas e Hidrofílicas , Imunoglobulina G/química , Emulsões , Humanos
3.
Rev Sci Instrum ; 89(10): 106102, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30399692

RESUMO

The ability to conduct en-route centrifugation of samples improves quality and timeliness in the pre-analytical phase. This is demonstrated here on a quadcopter whereby the propellers were adapted to house and apply centrifugal forces to sample-containing capillary tubes instead of incorporating a centrifuge. Tests revealed the ability of the method to separate non-homogenized milk into a cream portion and a skim milk portion, and human whole blood into plasma, buffy coat, and red blood cell components.

4.
Anal Biochem ; 545: 1-3, 2018 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-29307634

RESUMO

Autonomous systems for sample transport to the laboratory for analysis can be improved in terms of timeliness, cost and error mitigation in the pre-analytical testing phase. Drones have been reported for outdoor sample transport but incorporating devices on them to attain homogenous mixing of reagents during flight to enhance sample processing timeliness is limited by payload issues. It is shown here that flipping maneuvers conducted with quadcopters are able to facilitate complete and gentle mixing. This capability incorporated during automated sample transport serves to address an important factor contributing to pre-analytical variability which ultimately impacts on test result reliability.


Assuntos
Testes Imediatos , Impressão Tridimensional , Biomarcadores/análise , Humanos , Testes Imediatos/economia , Impressão Tridimensional/economia , Impressão Tridimensional/instrumentação
5.
ACS Omega ; 2(9): 6211-6222, 2017 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31457866

RESUMO

Drops with larger volumes placed over a superhydrophobic (SH) surface with a hole do not fall through unless they are evaporated to a size that is small enough. This feature offers the ability to preconcentrate samples for biochemical analysis. In this work, the influence of pinning on the behavior of drops placed on a 0.1 mm thick SH substrate with a 2 mm diameter hole as they evaporated was investigated. With 16 µL of water dispensed, the sessile drop component volume was initially higher than that of the overhanging drop component and maintained this until the later stages where almost identical shapes were attained and full evaporation was achieved without falling off the hole. With 15 µL of water dispensed, the volume of the sessile drop was initially higher than that of the overhanging drop component but the liquid body was able to squeeze through the hole after 180 s due to the contact line not having sufficient pinning strength when it encountered the edge of the hole. This resulted in the liquid body either falling through the hole or remaining pinned with an oval-like shape. When it did not fall-off, the liquid body had volume and contact angle characteristics for the sessile drop and overhanging drop components that were reversed. In the later stages, however, nearly identical shapes were again attained and full evaporation was achieved without falling off the hole. The effects of pinning, despite the substrate being SH, offer another path toward achieving practical outcomes with liquid bodies without the need for chemical surface functionalization. Similarities and differences could be seen in the behavior of a sessile drop on a SH plate that was inclined at 30° to the horizontal and evaporated.

6.
Langmuir ; 32(33): 8550-6, 2016 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-27479030

RESUMO

In this work, 2 µL water drops are placed on substrates that are created to have a circular hydrophilic region bounded by superhydrophobicity so that they exhibit high contact angles. When the substrate is translated by a linear stepper actuator, the random force components present in the actuator are shown to cause the drop to rock resonantly. When the substrate is translated downward at inclination angles of up to 6° with respect to the horizontal, the contact angle hysteresis increases progressively to a limiting condition. When the substrate is moved up at inclined angles, alternatively, the contact angle hysteresis increases initially to the limiting condition before it is progressively restored to its static state. These behaviors are accounted for by the reversible micro-Cassie to Wenzel wetting state transformations that are made possible by the hierarchical microscale and nanoscale structures present in the superhydrophobic regions.

7.
Eur Phys J E Soft Matter ; 38(11): 119, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26577818

RESUMO

We advance a scheme in which a liquid body on a stationary tip in contact with a rotating superhydrophobic surface is able to maintain resonance primarily from stick-slip events. With tip-to-surface spacing in the range 2.73 ≤ h < 2.45 mm for a volume of 10 µL, the liquid body was found to exhibit resonance independent of the speed of the drum. The mechanics were found to be due to a surface-tension-controlled vibration mode based on the natural frequency values determined. With spacing in the range 2.45 ≤ h < 2.15 mm imposed for a volume of 10 µL, the contact length of the liquid body was found to vary with rotation of the SH drum. This was due to the stick-slip events being able to generate higher energy fluctuations causing the liquid-solid contact areas to vary since the almost oblate spheroid shape of the liquid body had intrinsically higher surface energies. This resulted in the natural frequency perturbations being frequency- and amplitude-modulated over a lower frequency carrier. These findings have positive implications for microfluidic sensing.


Assuntos
Microfluídica , Nanoestruturas/química , Interações Hidrofóbicas e Hidrofílicas , Rotação , Propriedades de Superfície
8.
Langmuir ; 30(46): 13731-6, 2014 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-25370431

RESUMO

In this work, drop formation on a slightly inclined superhydrophobic substrate with liquid at various flow rates delivered through a semispherical well was investigated. Due to the initial dry well condition in the first drop produced, the inertial force from liquid filling allowed the well's edge hysteresis to be more readily breached, in which flow rates of 16 mL/min and above could create a jet that appeared to be able to "pierce" through the top of the semispherical drop without disrupting its form and growth very much. For subsequent drops, the well's edge hysteresis at flow rates of 14 mL/min and above helped to support an "egg" like form. In contrast, this form could not be developed on a similarly inclined superhydrophobic substrate without a well. The findings here assist to establish the flow rate ranges for consistent discrete volume delivery in biochemical analysis and serves as a means to conduct investigations to better reconcile the tendency of liquids to assume drops or develop jets.

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