Influence of volume phase transition phenomena on the behavior of hydrogel-based valves

Richter, Andreas; Howitz, S.; Kuckling, Dirk; Arndt, Karl‐Friedrich

doi:10.1016/j.snb.2003.12.014

Cited by 119 publications

(88 citation statements)

References 13 publications

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“…Previous workers have reported on the fabrication of temperature-responsive hydrogel valves [36][37][38][39]. For example, Yu et al prepared monolithic plugs of hydrogel by photo-initiated polymerization within the conduits of a microfluidic device and demonstrated over 120 openclose cycles [37].…”

Section: Introductionmentioning

confidence: 99%

“…For example, Yu et al prepared monolithic plugs of hydrogel by photo-initiated polymerization within the conduits of a microfluidic device and demonstrated over 120 openclose cycles [37]. Richter et al reported on a microvalve, which can be electronically controlled by a thermal-electronic interface [38,39]. In this paper, we focus on the integration of thermoresponsive, hydrogel microvalves into various components of a microfluidic system used for liquid distribution, metering, and the sealing of a PCR reactor to suppress bubble formation.…”

Section: Introductionmentioning

confidence: 99%

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Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip

Wang

Chen

Mauk

et al. 2005

Biomed Microdevices

146

108

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An easy to fabricate, thermally-actuated, self-regulated hydrogel valve for flow control in pneumatically driven, microfluidic systems is described. This microvalve takes advantage of the properties of the hydrogel, poly(Nisopropylacrylamide), as well as the aqueous fluid itself to realize flow control. The valve was designed for use in a diagnostic system fabricated with polycarbonate and aimed at the detection of pathogens in oral fluids at the location of the sample collection. The paper describes the construction and characterization of the hydrogel valves and their application for flow control, sample and reagent metering, sample distribution into multiple analysis paths, and the sealing of a polymerase chain reaction (PCR) reactor to suppress bubble formation. The hydrogel-based flow control is electronically addressable, does not require any moving parts, introduces minimal dead volume, is leakage and contaminant free, and is biocompatible. KeywordsMicrovalve, microfluidics, hydrogel, lab-on-a-chip, metering, distribution, PCR Wang, J., Chen, Z., Mauk, M., Hong, K-S, Li, M., Yang, S., and Bau, H., H Wang, J., Chen, Z., Mauk, M., Hong, K-S, Li, M., Yang, S., and Bau, H., H., 2005, Self-Actuated, ThermoResponsive Hydrogel Valves for Lab on a Chip, Biomedical Microdevices 7 (4), 313-322.., 2005, Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip, Biomedical Microdevices 7 (4), 313-322. ABSTRACTAn easy to fabricate, thermally-actuated, self-regulated hydrogel valve for flow control in pneumatically driven, microfluidic systems is described. This microvalve takes advantage of the properties of the hydrogel, poly(N-isopropylacrylamide), as well as the aqueous fluid itself to realize flow control. The valve was designed for use in a diagnostic system fabricated with polycarbonate and aimed at the detection of pathogens in oral fluids at the location of the sample collection. The paper describes the construction and characterization of the hydrogel valves and their application for flow control, sample and reagent metering, sample distribution into multiple analysis paths, and the sealing of a polymerase chain reaction (PCR) reactor to suppress bubble formation. The hydrogel-based flow control is electronically addressable, does not require any moving parts, introduces minimal dead volume, is leakage and contaminant free, and is biocompatible.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip

Wang

Chen

Mauk

et al. 2005

Biomed Microdevices

146

108

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“…11 Microvalves with electrothermic interface. a Photo-patterned actuators, each of the three actuators is (100 x 100 x 50)~m3 in size; b Set-up and operating principle of a microgel-based microvalve [30,31] The actuators of the microvalves shown in Fig. 11 are directly placed within the channels, enabling the device to be set up simply.…”

Section: Hydrogel (Swo Llen)mentioning

confidence: 99%

“…If it is filled to a low degree this provides 12 Operating behavior of the microvalves. a The opening time depending on the applied heating power; b Influence of the degree to which the actuator chamber is filled on the pressure resistance and switching time of the microvalve [30,31] short opening times but long closing times, while a high degree decreases the closing time and increases the opening time. The degree to which the actuator chamber is filled with actuator material also influences the pressure resistance of the valve.…”

Section: Hydrogel (Swo Llen)mentioning

confidence: 99%

Synthesis of Stimuli-Sensitive Hydrogels in the μm and sub-μm Range by Radiation Techniques and their Application

Arndt¹,

Richter²,

Mönch

2009

Hydrogels

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Abstract. The macroscopic material properties (elasticity, volume in swollen state) of smart stimuli-sensitive hydrogels show a strong dependence on the properties of an aqueous environment (swelling agent). This behavior can be used for sensors or force-generating elements (actuators). Radiochemistry offers the possibility to synthesize smart gels in a wide range of dimensions. As an example of temperature-sensitive polymers we demonstrate the advantages of a radiochemical-based approach for hydrogel synthesis. Structures in the urn and sub-urn range on a support were synthesized using different techniques. The applications of particles and patterned layers in the urn range were demonstrated using the example of devices for handling liquids 1 Stimuli-sensitive hydrogels Polymeric gels are most generally understood to be polymeric networks which absorb enough solvent to cause macroscopic changes in the sample dimension. Hydrogels are crosslinked hydrophilic polymers swollen in water. Most of their properties are directly influenced by the degree of swelling. The volume phase transition of certain hydrogels is one of the most fascinating and important phenomena in the physical chemistry of polymeric networks. Stimuli-sensitive hydrogels (they are also termed smart gels and responsive gels) are materials whose properties change in response to specific environmental stimuli (see Table 1). They change their volume (equilibrium degree of swelling), mechanical properties (elasticity, stiffness) and molecular transport properties, in response to a small change in the properties of the swelling agent, like temperature, solvent composition, pH value, mechanical strain, ion concentration, etc. The change in the degree of swelling may occur discontinuously at a specific value of stimulus or gradually over a (mostly small) range of stimulus values.Polymer gels have found wide application in various fields: medicine, agriculture, biotechnology, nutritive industry, petrochemical industry, etc. For these applications only the ability of a gel to absorb solvent and to swell is important, not the relationship between changes in the environment and swelling.The ability to directly convert chemical energy into mechanical work makes smart gels candidates for actuator and sensor systems, which can operate without additional Barbucci R. (Ed): Hydrogels. Biological Properties and Applications.

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“…It has been suggested that these hydrogels could be made into various forms (e.g., particle-like, film-like, fiber-like) and used as the basis for artificial organs, 8 drug delivery systems, 9 separation systems, 10 or on-off switches. 11,12 As a special form, smart hydrogel fibers, which can reversibly elongate and contract in response to external stimuli, have been extensively investigated. Such behavior is partially similar to the contraction properties of natural muscle (the electrical signal from the nervous system triggers a series of chemical processes that lead to a volume change and a concomitant mechanical movement, developing mechanical energy), so a lot of researchers and technologists become interested in the development of ''artificial muscle.''…”

Section: Introductionmentioning

confidence: 99%

Preparation and characterization of pH‐sensitive hydrogel fibers based on hydrolyzed‐polyacrylonitrile/soy protein

Yan

Sun

et al. 2008

J of Applied Polymer Sci

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Novel smart hydrogel fibers were prepared from a blend of hydrolyzed-polyacrylonitrile (H-PAN) and Soy Protein (SP). The dynamic and static elongation/contraction behaviors were studied. It was discovered that H-PAN/ SP hydrogel fibers consisted of a multiporous structure. With an increase in the content of SP, the hydrogel fibers exhibited excellent reversible pH-sensitive behavior. When the weight ratio of H-PAN to SP was 4 : 6, the hydrogel fibers showed the best response times at 1.35 s (elongation) and 0.63 s (contraction). Discontinuous volume phase transitions and hysteresis loops of the hydrogel fibers induced by changes in pH value were found. These results were found to be explicable in terms of the surface morphology and polyampholytic properties of H-PAN/SP hydrogel fibers.

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Influence of volume phase transition phenomena on the behavior of hydrogel-based valves

Cited by 119 publications

References 13 publications

Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip

Self-Actuated, Thermo-Responsive Hydrogel Valves for Lab on a Chip

Synthesis of Stimuli-Sensitive Hydrogels in the μm and sub-μm Range by Radiation Techniques and their Application

Preparation and characterization of pH‐sensitive hydrogel fibers based on hydrolyzed‐polyacrylonitrile/soy protein

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