Static control logic for microfluidic devices using pressure-gain valves

Weaver, James; Melin, Jessica; Stark, D.; Quake, Stephen R.; Horowitz, Mark

doi:10.1038/nphys1513

Cited by 124 publications

(131 citation statements)

References 24 publications

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“…Since the theory and simulation methods of electric circuits are wellestablished, they greatly facilitate the design and analysis of various microfluidic circuits. 1 Recently, analogy has been drawn between electronic transistors and microfluidic membrane-valves (lMV), which are used for self-regulated microfluidic circuits such as frequency-specific flow regulators, 2 digital logic circuits, [3][4][5][6] and oscillators. [7][8][9] Like an electronic circuit that operates itself with only a power source and thus minimize the use of its external controllers, the self-regulated microfluidic circuits have the potential to greatly reduce reliance on expensive and complex external controllers, which are barriers to broader use of microfluidic devices.…”

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confidence: 99%

Analyzing threshold pressure limitations in microfluidic transistors for self-regulated microfluidic circuits

Kim

Yokokawa

Takayama

2012

Applied Physics Letters

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This paper reveals a critical limitation in the electro-hydraulic analogy between a microfluidic membrane-valve (lMV) and an electronic transistor. Unlike typical transistors that have similar on and off threshold voltages, in hydraulic lMVs, the threshold pressures for opening and closing are significantly different and can change, even for the same lMVs depending on overall circuit design and operation conditions. We explain, in particular, how the negative values of the closing threshold pressures significantly constrain operation of even simple hydraulic lMV circuits such as autonomously switching two-valve microfluidic oscillators. These understandings have significant implications in designing self-regulated microfluidic devices. Electric circuit analogy is widely used in microfluidic circuit design and analysis. For example, electric resistors correspond to microfluidic channel resistances and capacitors to flexible membranes. The analogy is based on the similarity in equations between these circuit components. Since the theory and simulation methods of electric circuits are wellestablished, they greatly facilitate the design and analysis of various microfluidic circuits. 1 Recently, analogy has been drawn between electronic transistors and microfluidic membrane-valves (lMV), which are used for self-regulated microfluidic circuits such as frequency-specific flow regulators, 2 digital logic circuits, [3][4][5][6] and oscillators. [7][8][9] Like an electronic circuit that operates itself with only a power source and thus minimize the use of its external controllers, the self-regulated microfluidic circuits have the potential to greatly reduce reliance on expensive and complex external controllers, which are barriers to broader use of microfluidic devices. A lMV is a crucial component that enables operation of self-regulated microfluidic devices through its on-off switching.Similar to the electronic transistor, the lMV's on-off switching is determined by the relative difference between the source (P S ) minus gate pressure (P G ) versus the threshold pressure ( Figure 1). As depicted in Figure 1(a), when P S is sufficiently greater than P G , the membrane of the lMV deflects down and the lMV is on (open). In other words, the lMV is on when P S À P G is greater than opening threshold pressure (P th-open ). To turn off (close) the lMV, P S À P G is less than closing threshold pressure (P th-close ). In typical silicon transistors, 10,11 the difference between on and off threshold voltage is negligible, thus providing a large parameter space for the design and operation of large-scale integrated circuits. Pneumatic lMVs also exhibit small differences between opening (P th-open ) and closing (P th-close ) threshold pressures. 5,12 However, in self-regulated microfluidic devices, the detailed characteristic of lMV's threshold pressure in the context of other microfluidic parameters such as fluidic resistor and inflow rate is largely unknown.Here, we report that P th-open and P th-close are significantly differe...

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confidence: 99%

Analyzing threshold pressure limitations in microfluidic transistors for self-regulated microfluidic circuits

Kim

Yokokawa

Takayama

2012

Applied Physics Letters

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“…This intrinsic nonlinear gain is characteristic of all vacuum-driven pneumatic logic technologies (7,8). In contrast, pressure-driven hydraulic technologies require additional engineering to achieve gain (9,10,23,24).…”

Section: Resultsmentioning

confidence: 99%

“…Using elastomeric valves as transistor analogs, various groups have demonstrated fundamental building blocks such as Boolean logic gates (6-10), memory latches (6,(8)(9)(10), and frequency-sensitive valves (11,12), as well as more complex systems such as shift-registers (7,8,10) and adders (7). Digital logic operations have also been demonstrated by using microfluidic droplets to represent binary information (13)(14)(15).…”

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confidence: 99%

Pneumatic oscillator circuits for timing and control of integrated microfluidics

Duncan

Nguyen

Hui

2013

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

109

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Significance Lab-on-a-chip devices aim to miniaturize laboratory procedures on microfluidic chips, which contain liquid circuits instead of electronics. Although the chips themselves are small, they are typically dependent on off-chip control machinery that negates their size advantage. If a computer controller could be built out of microfluidic valves and channels, it could be integrated to create a complete system-on-a-chip. We engineer a critical component for such a computer: a microfluidic clock oscillator with suitable timing accuracy to control diagnostic assays. Further, we leverage this oscillator to build a self-driving pump for on-chip liquid transport. Thus, we demonstrate two critical components for building self-contained lab-on-a-chip devices.

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“…Commonly, these membrane (or 'Quake') valves are two-layer constructions that use multiple pneumatic inputs to control complex arrays of microfluidic reactors, although some studies use multiple layers to implement valves with active control or integrated pressure gain 69,70 . Fully 3D-printed microfluidic systems with valving mechanisms have also been developed 22,[71][72][73] .…”

Section: Multisided and Multilayer Molding Techniquesmentioning

confidence: 99%

Rapid assembly of multilayer microfluidic structures via 3D-printed transfer molding and bonding

et al. 2016

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A critical feature of state-of-the-art microfluidic technologies is the ability to fabricate multilayer structures without relying on the expensive equipment and facilities required by soft lithography-defined processes. Here, three-dimensional (3D) printed polymer molds are used to construct multilayer poly(dimethylsiloxane) (PDMS) devices by employing unique molding, bonding, alignment, and rapid assembly processes. Specifically, a novel single-layer, two-sided molding method is developed to realize two channel levels, non-planar membranes/valves, vertical interconnects (vias) between channel levels, and integrated inlet/outlet ports for fast linkages to external fluidic systems. As a demonstration, a single-layer membrane microvalve is constructed and tested by applying various gate pressures under parametric variation of source pressure, illustrating a high degree of flow rate control. In addition, multilayer structures are fabricated through an intralayer bonding procedure that uses custom 3D-printed stamps to selectively apply uncured liquid PDMS adhesive only to bonding interfaces without clogging fluidic channels. Using integrated alignment marks to accurately position both stamps and individual layers, this technique is demonstrated by rapidly assembling a six-layer microfluidic device. By combining the versatility of 3D printing while retaining the favorable mechanical and biological properties of PDMS, this work can potentially open up a new class of manufacturing techniques for multilayer microfluidic systems.

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Static control logic for microfluidic devices using pressure-gain valves

Cited by 124 publications

References 24 publications

Analyzing threshold pressure limitations in microfluidic transistors for self-regulated microfluidic circuits

Analyzing threshold pressure limitations in microfluidic transistors for self-regulated microfluidic circuits

Pneumatic oscillator circuits for timing and control of integrated microfluidics

Rapid assembly of multilayer microfluidic structures via 3D-printed transfer molding and bonding

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