Electrohydrodynamic device

Labbaf, S., S. Deb, G. Cama, E. Stride, and M. Edirisinghe. Preparation of multicompartment submicron particles using a triple-needle electrohydrodynamic device. Journal of Colloid and Interface Science 409 (2013) 245-254. 

This electrohydrodynamic (EHD) mixer (Figure 1.6) device provides a simple flowthrough chamber which has an upper and lower electrode for generating a electromagnetic field. The chamber channel is given by a sandwich of two plates, one being microstructured [94], The bottom plate contains a trapezoid channel. Two electrode layers are deposited on parts of the channel bottom and channel top and on the top part of this plate so that they reach the outside for external electrical contact. 

Zimlich WC. The development of a novel electrohydrodynamic (EHD) pulmonary dmg delivery device. In Respiratory Dmg Delivery VII Dalby RN, Byron PR, Farr SJ, eds. Interpharm Press Tarpon Springs, FL, 2000 241-246. 

Electrokinetic/Electrohydrodynamic Flow Instability, Fig. 3 Eiectrohydrodynamic mixing in a DC electric field. The images show the outlet branch of the microchannel after the device has been loaded with two fluids, (a) The initial condition showing a dark green fluid... 

Electrokinetic and electrohydrodynamic instability mixing in microsystems is a complex phenomenon which researchers are only beginning to exploit and understand. Future work requires a further development of experimental models and expansion of computational simulations to better understand how the instabilities form and grow. Specific applications of electrokinetic and electrohydrodynamic instabilities are still limited. The application of these instabilities to improve mixing between components should be explored. One example is through the use of multiphase systems where electrohydrodynamic instabilities are utilized to improve component partitioning for liquid extraction devices. 

In this section, we discuss recent developments on various interfacial electrokinetic flow phenomena that have potential applications in microfluidic devices. In particular, we focus on electrohydrodynamic atomization (or more commonly known as electrospraying) and... 

The surface and bulk electrohydrodynamic recirculation, while having the usual advantages of electrokinetic devices wherein mechanically moving parts are absent, also benefit from low field penetration into the liquid given that the... 

Inkjet printing technology can be used with an electrohydrodynamic spraying technique (24). A conventional electrohydrodynamic inkjet device is based on DC voltage and requires two electrodes a nozzle electrode and an extractor electrode. However, this device suffers from drawbacks such as electrical breakdown. A more stable jetting technique uses the extractor electrode alone without the nozzle electrode and AC voltage. Thus, a continuous ejection of droplets can be obtained due to AC voltage. 

The term active mixer or active microimxef refers to a microfluidic device in which species mixing is enhanced by the application of some form of external energy disturbance. Typically, this disturbance is generated either by moving components within the micromixer itself, e.g. magnetically-actuated stirrers, or by the application of an external force field, e. g. pressure, ultrasound, acoustic, electrohydrodynamic, electrokinetic, dielectrophoretic, magneto-hydrodynamic, thermal, and so forth [1]. 

In the same way that the molecules of N phases can be electrically reoriented, the molecules of the smectic phase can be dielectrically reoriented by electric fields, albeit at a higher voltage. However, unlike in the N phase, when the field is removed, the bulk viscosity of the smectic phase inhibits relaxation and bistability is favored. This can be an advantage unless the procedure has to be reversed, because this cannot be achieved so easily. Reversal is accomplished by heating to either the less viscous N or isotropic liquid phases (as used in the laser and thermally addressed devices) or by causing electrohydrodynamic scattering to occur (see Sec. 3.6). In this section we shall specifically consider the dielectric reorientation effect. In itself it may not be particularly useful, but when combined with other techniques, it can lead to interesting devices. 

---