Study of chemically induced pressure generation of hydrogels under isochoric conditions using a microfabricated device

Herber, S. and Eijkel, J. and Olthuis, W. and Bergveld, P. and Berg van den, A. (2004) Study of chemically induced pressure generation of hydrogels under isochoric conditions using a microfabricated device. Journal of Chemical Physics, 121 (6). pp. 2746-2751. ISSN 0021-9606

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Abstract:	A method is proposed to study the behavior of stimulus-sensitive hydrogels under isochoric conditions. Freedom of swell movement of such a hydrogel was restricted in all directions by enclosing the hydrogel between a micropressure sensor and a porous cover. Water and external stimuli can be applied to the hydrogel through the pores of the cover to provoke swelling, which results in pressure generation measured by the pressure sensor. The method was put to the proof by examining the response of a pH-sensitive hydrogel to changes in pH, ionic strength, and buffer concentrations of the surrounding solution. Both equilibrium and dynamic pressure generation were observed. The results show that higher pressures are obtained by incorporating more ionizable groups into the hydrogel network or by lowering the ionic strength of the external solution. Furthermore it was proven that pressures reach equilibrium faster when less titratable groups are incorporated or at the presence of higher buffer concentrations in the surrounding solution. By using microfabrication techniques the dimensions of the hydrogel could be kept small with the advantage that responses are fast. A DMAEMA-co-HEMA hydrogel with 2.5% protonable groups and a thickness of 15 mm generated a Dpressure of 0.673105 Pa in 12 min when a pH step from 9 to 6 was applied. The presented method is a simple and fast manner to characterize the static and dynamic stimulus-dependent behavior of hydrogels.
Item Type:	Article
Copyright:	© 2004 American Institute of Physics
Faculty:	Electrical Engineering, Mathematics and Computer Science (EEMCS)
Research Group:	Biomedical and Environmental Sensor systems (BIOS)
Link to this item:	http://purl.utwente.nl/publications/47855
Official URL:	http://dx.doi.org/10.1063/1.1773153
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