Hydrogel-based reconfigurable components for microfluidic devices

Kim, Dongshin; Beebe, David J.

doi:10.1039/b612995a

Cited by 76 publications

(67 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One region where more immediate application seems likely is in valves for the delivery of small amounts of liquids, where electromechanical systems tend to be clumsy and unreliable. [168][169][170] Most gel systems bend in an electric field, because the two sides of the gel respond differently to the positive and negative potentials. The actual response mechanisms depend on whether the electrodes are embedded in the gel or are in the fluid.…”

Section: Actuators and Artificial Musclesmentioning

confidence: 99%

Hydrogels for Soft Machines

2009

View full text Add to dashboard Cite

Hydrogels have applications in surgery and drug delivery, but are never considered alongside polymers and composites as materials for mechanical design. This is because synthetic hydrogels are in general very weak. In contrast, many biological gel composites, such as cartilage, are quite strong, and function as tough, shock‐absorbing structural solids. The recent development of strong hydrogels suggests that it may be possible to design new families of strong gels that would allow the design of soft biomimetic machines, which have not previously been possible.

show abstract

Section: Actuators and Artificial Musclesmentioning

confidence: 99%

Hydrogels for Soft Machines

2009

View full text Add to dashboard Cite

show abstract

“…Active gels have been developed as valves for microfluidic systems, where swelling of the gel in response to light, pH, thermal or electrical stimulation can be used to close a fluid channel or act as a pump [37,126,176,[179][180][181]. Electrically driven gels essentially respond to local changes in pH or ionic strength caused by electrolysis of the water [179,182].…”

Section: Gel Valves and Pumpsmentioning

confidence: 99%

Polymer Gel Actuators: Fundamentals

Calvert

2009

Biomedical Applications of Electroactive Polymer Actuators

View full text Add to dashboard Cite

One view of materials development is to search for what materials correspond to empty spaces on a hypothetical multi-dimensional map of the properties of available materials. Following a biomimetic philosophy, for instance, it can be seen that tough ceramics and moldable short fiber composites with high moduli are possible but absent from the list of available synthetic materials. Likewise artificial muscle is missing, where the properties are defined as a developed stress of over 300 kPa, a linear contraction of 25 % and a response time of below one second. Currently dielectric elastomers come closest but have disadvantages [1,2].The actin-myosin muscle system provides the performance target for electroactive polymer actuators [3,4]. The process is driven chemically by the energy change from hydrolysis of the polyphosphate bond as ATP (adenosine triphosphate) binds to myosin and is converted to ADP (adenosine diphosphate) and phosphate. A simple chemical analogy suggests that muscle-like gels should be feasible but it is now clear that the task is much harder than it seems.Early work on gel actuation by Katchalsky-Katzir demonstrated that engines could be built using the chemical energy in diluting a lithium bromide solution to drive contraction and expansion of a collagen belt [5]. In essence, the collagen expands to take up the salt solution or contract to exclude the water. This change is both a molecular conformation change and a volume change. Other chemically driven gels, for instance polyacrylic acid fibers [6] which respond to a pH change, also rely on a solubility change giving rise to a volume change.

show abstract

“…[6][7][8][9][10][11] This approach is appealing for optical data storage, 12 actuators 1 and valves in microfluidics. [13][14][15][16][17][18][19][20][21] In particular, the latter application ideally requires fast and large actuation of the valve structure in order to work efficiently. However, up to now, most examples are based on temperature responsive systems, which is not readily implementable in microfluidics.…”

Section: Introductionmentioning

confidence: 99%

Molecular Design of Light-Responsive Hydrogels, For in Situ Generation of Fast and Reversible Valves for Microfluidic Applications

Schiphorst¹,

Coleman

Stumpel³

et al. 2015

Chem. Mater.

148

142

View full text Add to dashboard Cite

Light--responsive hydrogel valves with enhanced response characteristics compatible with microfluidics have been obtained by optimization of molecular design of spiropyran photoswitches and gel composition. Self--protonating gel formulations were exploited, wherein acrylic acid was copolymerized in the hydrogel network as an internal proton do--nor, to achieve a swollen state of the hydrogel in water at neutral pH. Light--responsive properties were endowed upon the hydrogels by copolymerization of spiropyran chromophores, using electron withdrawing and donating groups to tune the gel--swelling rate. Faster macroscopic swelling of the hydrogels was obtained by changing an ester to an ether at the 6' position (factor of 4) or shifting the ether group to the 8' position of the spiropyran (factor of 2.5) producing a 10 fold increase in total. The effect was also visible in the swelling behavior of the corresponding hydrogel valves, where the ob--served macroscopic changes were reversible and reproducible and in agreement with the molecular kinetics. Gel--valves integrated within microfluidic channels have been fabricated and allow reversible and repeatable operation, with opening of the valve effected in 1 minute, while closing takes around 5.5 minutes.

show abstract

Hydrogel-based reconfigurable components for microfluidic devices

Cited by 76 publications

References 35 publications

Hydrogels for Soft Machines

Hydrogels for Soft Machines

Polymer Gel Actuators: Fundamentals

Molecular Design of Light-Responsive Hydrogels, For in Situ Generation of Fast and Reversible Valves for Microfluidic Applications

Contact Info

Product

Resources

About