Understanding Dielectrophoresis

Dielectrophoresis (DEP) is the translational movement of an electrically polarisable substance caused by an externally applied, non-uniform electric field. Dielectrophoresis can occur in a regionally non-uniform field with an electrically neutral material and is dependent on the dielectric characteristics of the object relative to a surrounding medium. 

Dielectrophoresis is a combination of two words: dielectro, which refers to the motion’s dependency on the dielectric characteristics of the body, and phoresis, which refers to motion. DEP differs from electrophoresis in that a net charge on the body is required for Coulombic movement to happen in an applied external, spatially homogeneous electric field.

Dielectrophoresis enables cell separation, nanoparticle orientation and manipulation, and so forth. Dielectric characteristics exist in biological cells. As a result, this approach has several applications in medicine. It may be used to distinguish cancer cells and healthy cells, for example. Platelets can also be isolated from other types of blood cells. Furthermore, dielectrophoresis is important in the manufacture of semiconductors.

What is Dielectrophoresis?

Dielectrophoresis (DEP) is an analytic approach that applies a force on dielectric particles when they are in a non-uniform electromagnetic current. The particles do not need to be charged in order to be separated using this approach.

The intensity of the force exerted on the dielectric particle, on the other hand, is determined by the kind of media, the electrical characteristics of the particles, and the shape and size of the particles.

Biomolecules are physiologically relevant organic compounds that also include nucleic acids, proteins, carbohydrates, and lipids. Deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and artificial polynucleic acid (PNA) are nucleic acids. Bio-colloidal nanospheres, which are frequently functionalized using biomolecules and are strong tools in today’s laboratory, are also examined in this article.

We will discuss the fundamental theoretical concepts of dielectric polarisation that lead to DEP motion. For simplicity, these theoretical ideas are centred on two biomolecules that serve as key examples: 

• DNA that behaves in water as a stringy, worm-like chain
• Nanospheres that behave extremely differently as ideal bio-colloids, or compact biomolecules with a well-defined particle-solution interface

What Distinguishes Dielectrophoresis from Electrophoresis?

The primary distinction between electrophoresis and dielectrophoresis is that electrophoresis separates ionised particles whereas dielectrophoresis separates either charged or uncharged particles.

These are ways to separate desirable bits from a mixture of particles.

What is Positive Dielectrophoresis?

• When particles are manipulated by forces acting in the direction of an increasing electric field, positive dielectrophoresis occurs. 
• Negative dielectrophoresis occurs when particles are manipulated by forces acting in the direction of a decreasing electric field.

What is the Electrowetting Effect?

The electrowetting effect is characterised as a change in solid-electrolyte contact angle caused by a potential difference between the solid and the electrolyte. The energy stored in the capacitor produced between the conductor, and the electrolyte is the electrical component.

Dielectrophoresis Applications

• Dielectrophoresis may be used to transport and control extremely tiny biomolecules, regardless of whether they have a net electrical charge. 
• Dielectrophoresis allows AC voltages at suitable radio frequencies (RFs) to cause DEP-driven motion while avoiding troublesome hydrolysis at the solution-electrode interface. 
• These characteristics make dielectrophoresis suitable for regulating biomolecular mobility, especially when used at low voltages in a micro-device setting. 
• Dielectrophoresis is inexpensive to use in systems like Lab-On-Chip (LOC) or micro-Total Analysis System (mTAS).

Conclusion

The primary distinction between electrophoresis and dielectrophoresis is that electrophoresis separates charged particles, whereas dielectrophoresis separates either charged or non-charged particles. Electrophoresis and dielectrophoresis are critical analytical procedures in biochemistry.