Solenoid pumps micropumps

Figure 2.18 shows an MPFS system capable of performing the speciation of Fe(II) and Fe(III) with and without preconcentration depending on the results successively obtained [21]. The system uses five micro-solenoid pumps (MPs) and a solenoid valve (V). Micropumps are used to insert the sample, carrier, eluent (HCl), oxidant (hydrogen peroxide), and chromogenic reagent (ammonium... 

The controlled-release micropump (Figure 2) is a recently invented device that uses the principles of membrane transport and controlled release of drugs to deliver insulin at variable rates (20,26). With a suitable supply of insulin connected to the pump, the concentration and/or pressure difference across the membrane results in diffusion or bulk transport through the membrane ). This process is the basal delivery and requires no external power source. Augmented delivery is achieved by repeated compression of the foam membrane by the coated mild-steel piston. The piston is the core of the solenoid, and compression is effected when current is applied to the solenoid coil. Interruption of the current causes the membrane to relax, drawing more drug into the membrane in preparation for the next compression cycle. 

Apparatuses are devices which can perform mechanical operations but not make measurements. Many are essential elements of flow assembhes, e.g. syringe pumps, peristaltic pumps, selection valves, micropumps, external solenoid valves. Although commercially available in a wide variety of forms and models, many apparatuses lack an interface for connection to a computer. This should be an important consideration at the time of purchase. However, since they rarely need to feed back information to the computer, they can operate one-way (to receive commands from the computer). Table 6.2 lists available DLLs for apparatuses. 

Other alternative is the use of micropumps as proposed by Lapa et al. [23]. In this study, authors describe a strategy exploiting solenoid micropumps for each individual solution insertion (sample and carrier), controlling not only its volume but also the timing, sequence of introduction and transportation toward detector. This strategy was evaluated by using a flow network designed with two pumps. 

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