Microfluidic phase change valve with a two-level cooling/heating system

Gui, Lin; Yu, Bo; Ren, Carolyn L.; Huissoon, Jan P.

doi:10.1007/s10404-010-0683-3

Cited by 18 publications

(21 citation statements)

References 27 publications

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“…The lowest closing time for the valve is 0.37 s at a flow rate of 10 μL/min. Compared with ice valves reported in previous studies111314, the closing time of this ice valve is over 8 times shorter at the same flow rates. Another significant improvement over previous studies is that this ice valve also exhibits good performance at high flow rates.…”

Section: Resultscontrasting

confidence: 46%

“…A few years later, this concept was expanded to use liquid nitrogen as the cooling medium10. However, such low temperature liquids and gases are hard to integrate into small devices and also have inherent safety problems11. In 2001, thermoelectric (TE) units were employed to freeze and thaw flow in capillaries12.…”

mentioning

confidence: 99%

“…A more recent study used a single-level (containing only one TE unit) ice valve with a more efficient design and the valve closing time was reduced to 4.1 seconds14. The use of a two-level TE unit further decreased the valve closing time to 2.72 seconds11 by cooling the device to near 0 °C with one TE unit, and then lowering the temperature futher with the other TE unit. However, there is still a demand for improving the response speed and integration density of ice valves, especially for microfluidic applications where many processes occur in short timescales11.…”

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confidence: 99%

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High response speed microfluidic ice valves with enhanced thermal conductivity and a movable refrigeration source

Cao

et al. 2017

Sci Rep

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Due to their ease of fabrication, facile use and low cost, ice valves have great potential for use in microfluidic platforms. For this to be possible, a rapid response speed is key and hence there is still much scope for improvement in current ice valve technology. Therefore, in this study, an ice valve with enhanced thermal conductivity and a movable refrigeration source has been developed. An embedded aluminium cylinder is used to dramatically enhance the heat conduction performance of the microfluidic platform and a movable thermoelectric unit eliminates the thermal inertia, resulting in a faster cooling process. The proposed ice valve achieves very short closing times (0.37 s at 10 μL/min) and also operates at high flow rates (1150 μL/min). Furthermore, the response time of the valve decreased by a factor of 8 when compared to current state of the art technology.

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Section: Resultscontrasting

confidence: 46%

mentioning

confidence: 99%

mentioning

confidence: 99%

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High response speed microfluidic ice valves with enhanced thermal conductivity and a movable refrigeration source

Cao

et al. 2017

Sci Rep

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“…Recently, microfluidic devices have been used to study ice nucleation processes (24)(25)(26), cell injury by freezing (27), and thawfreezing cycle valves (28). Here we used a sensitive temperaturecontrolled system and custom-built microfluidic devices to slowly remove AFPs from the solution around individual ice crystals without perturbing the crystals or changing the temperature.…”

mentioning

confidence: 99%

Microfluidic experiments reveal that antifreeze proteins bound to ice crystals suffice to prevent their growth

Celik

Drori

Pertaya-Braun

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

156

142

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Antifreeze proteins (AFPs) are a subset of ice-binding proteins that control ice crystal growth. They have potential for the cryopreservation of cells, tissues, and organs, as well as for production and storage of food and protection of crops from frost. However, the detailed mechanism of action of AFPs is still unclear. Specifically, there is controversy regarding reversibility of binding of AFPs to crystal surfaces. The experimentally observed dependence of activity of AFPs on their concentration in solution appears to indicate that the binding is reversible. Here, by a series of experiments in temperature-controlled microfluidic devices, where the medium surrounding ice crystals can be exchanged, we show that the binding of hyperactive Tenebrio molitor AFP to ice crystals is practically irreversible and that surface-bound AFPs are sufficient to inhibit ice crystal growth even in solutions depleted of AFPs. These findings rule out theories of AFP activity relying on the presence of unbound protein molecules.thermal hysteresis | ice structuring proteins A ntifreeze proteins (AFPs) are found in a variety of coldadapted organisms, where they serve as inhibitors of ice crystal growth and recrystallization (1, 2). These proteins are a subset of an expanding group of identified proteins, whose salient feature is ice binding (3, 4). AFPs are characterized by their ability to cause a temperature difference (hysteresis) in the melting and freezing of ice and are classified as hyperactive or moderately active according to the magnitude of their freezing hysteresis (FH) activity (5). The FH activity is defined as the difference between the melting temperature of ice crystals and the nonequilibrium freezing temperature at which rapid crystal growth commences. Although the FH activity has been investigated for more than four decades, the actual mechanism of action of AFPs is still not clear. This is partly because the interactions between molecules of AFPs, water, and ice at the ice-water interface are difficult to study experimentally due to the delicate, transitory nature of the ice-water interface.FH activity is thought to be due to an adsorption-inhibition mechanism that states that AFPs bind to ice surfaces and allow ice crystal growth only in surface regions between the bound AFP molecules (6, 7). This patchy growth pattern causes increased local microcurvature of the ice front that leads to larger surface energy, making the transformation of water into ice less energetically favorable and thus reducing the freezing temperature (GibbsThompson effect). It has been argued that the binding of AFPs to ice surfaces must be irreversible, because AFP desorption would result in rapid crystal growth in the areas where the AFP molecules have been desorbed from the ice surface (6,8). This theory has been criticized for assuming that the ice-water interface is sharp, contrary to the experimental evidence that the transitions from an ordered solid phase to a liquid phase at the ice-water interfaces are gradual and occur over seve...

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“…As the flow rate increases above 40 µl/min the closure time increases rapidly. A different form is shown in Gui et al [9] in that their closure time always increases with the flow rate. This may be because they work with intermediate flow rates or be a result of their different setup that involves multiple channels and a pre-cooling section.…”

Section: 1mentioning

confidence: 99%

An approximate mathematical model for solidification of a flowing liquid in a microchannel

Myers

Low

2011

Microfluid Nanofluid

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Abstract. A mathematical model is developed to analyse the combined flow and solidification of a liquid in a small pipe or two-dimensional channel. In either case the problem reduces to solving a single equation for the position of the solidification front. Results show that for a large range of flow rates the closure time is approximately constant, and the value depends primarily on the wall temperature and channel width. However, the ice shape at closure will be very different for low and high fluxes. As the flow rate increases the closure time starts to depend on the flow rate until the closure time increases dramatically, subsequently the pipe will never close.

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Microfluidic phase change valve with a two-level cooling/heating system

Cited by 18 publications

References 27 publications

High response speed microfluidic ice valves with enhanced thermal conductivity and a movable refrigeration source

High response speed microfluidic ice valves with enhanced thermal conductivity and a movable refrigeration source

Microfluidic experiments reveal that antifreeze proteins bound to ice crystals suffice to prevent their growth

An approximate mathematical model for solidification of a flowing liquid in a microchannel

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