Hydrogel components

Run No. Hydrogels Component of Gel Prosta- glandin (hg) Degree of Inhibition (%) ... 

Fig. 3 Antagonistic hydrodynamic transistor types. The fully swollen state is assumed as normal state of the hydrogel component (a) Normally closed hydrodynamic transistors, (b) Normally open hydrodynamic transistors. The hydrogel acts as servo drive...

As resistive heating elements of this electrothermic interface thin film platinum resistors and surface mount technology (SMT) resistors are used (Richter et al. 2003, 2009a). The hydrogel components can be heated and cooled also by Peltier elements (Yu et al. 2003b Luo et al. 2003a). 

After the synthesis of the active hydrogel components these are often not immediately ready to operate and show an unsatisfying behaviour. During the design process the causes of malfunctions have to be considered to avoid inoperative devices. 

The swelling kinetics of stimuli-responsive hydrogels is described by the theory of cooperative diffusion (Sect. 3.2.2 and 3.2.3, (Tanaka and Fillmore 1979)). Besides the cooperative diffusion constant, which is specific for each solvent-polymer network combination (see Eq. (3.2.9)), the time behaviour of active hydrogel components can be as well influenced by further design-dependent aspects (Richter 2006, 2008b). 

Fig. 18 Influence of the effective diffusion length on the response time of a hydrogel component, (a) Bulk hydrogel component. The effective diffusion length is (7a- (b) Component with hydrogel particles. The component volume equals with that of the bulk component. The effective diffusion length is approximately rp...

Fig. 19 Swelling characteristics of hydrogel components at (a) different channel cross-sections Ac and (b) various counterforces. As hydrogel a poly(vinyl alcohol) / polyacrylic acid network is used (Arndt et al. 1999)...

Inside microfluidic channels the flow is laminar. Due to the absence of turbulences different media do not mix or mix only spontaneously and very slowly. Automatic elements can only operate correct in the presence of sufficient process medium. Otherwise, in the absence of stimulation, the control functionality can not be performed. Therefore, inside microfluidic channel networks the realisation of a recirculation is recommended which can provide an independency from the state (open or closed) of the active hydrogel components. 

Figure 8.7 Schematic representation of injectable hydrogels reinforced with cellulose nanocrystals (CNCs), prepared using a double-barrel inge. The crosslinking hydrogel components include hydrazide-fiinctionalized car-boxymethyl cellulose (CMC-NHNH2), aldehyde-functionalized dextran (dextran-CHO), and either unmodified CNCs or aldehyde-modified CNCs (CHO-CNCs).

Hydrogel components Preparation methods Degradation modes Applications Ref. 

Hydrogel components Preparafion methods Degradation inodes Applications Ref. 

An important parameter to consider is the aetuation of the hydrogel on the valve seat as well as the size of the hydrogel components, including the decision whether we use bulk or small hydrogels micropartieles enclosed in a chamber. This factor plays an important role in the performance of the device and will be briefly explored in the next section. 

Network formation Hydrogel components Ceramic filler Other bioactive agents... 

Hydrogel components mixture using two Martinez-Alvarez... 

A similar result is also indentified in a study on invasion of prostate cancer cells in the HA hydrogel, showing that the gel triggers the cells to express and localise the receptors for HA-mediated motility by interacting with the HA hydrogel components [53]. Hence, the gel scaffold made from HA may keep this function and contribute to the cellular migration. 

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