Taylor cone
Introduction
The Taylor cone is a shape that forms when a liquid is subjected to a sufficiently strong electric field. The term is named after Sir Geoffrey Ingram Taylor, a British physicist who first described the phenomenon in 1964. The formation of a Taylor cone is a crucial aspect of electrospray and electrospinning processes, and it plays a significant role in various fields such as material science, chemistry, and nanotechnology.
Formation of Taylor Cone
The formation of a Taylor cone occurs when a liquid droplet is subjected to a strong electric field. This causes the droplet to deform from a spherical shape into a conical shape, known as the Taylor cone. The apex of the cone is the point where the electric field is strongest, and it is from this point that a jet of liquid is often ejected in the electrospray process.
The formation of a Taylor cone is governed by a balance of forces. On one hand, the electric field exerts a force on the liquid droplet that tends to pull it into a conical shape. On the other hand, the surface tension of the liquid resists this deformation and tends to maintain the droplet in a spherical shape. When the electric field is sufficiently strong, it overcomes the surface tension, and a Taylor cone forms.
Mathematical Description
The shape of a Taylor cone can be described mathematically using the principles of fluid dynamics and electromagnetism. In his original paper, Taylor derived an equation for the half-angle of the cone, which is approximately 49.3 degrees. This value is remarkably consistent, regardless of the properties of the liquid or the strength of the electric field.
The mathematical description of a Taylor cone is based on the Laplace equation, which describes the electric potential in a region of space. By solving this equation under appropriate boundary conditions, it is possible to derive an expression for the shape of the Taylor cone.
Applications of Taylor Cone
The formation of a Taylor cone is a key aspect of electrospray and electrospinning processes, which have a wide range of applications.
In electrospray ionization, a technique used in mass spectrometry, a Taylor cone is formed at the tip of a capillary tube containing a liquid sample. A high voltage is applied to the tube, causing the liquid to form a Taylor cone and eject a jet of charged droplets. These droplets are then analyzed by the mass spectrometer to determine the molecular composition of the sample.
In electrospinning, a method used to produce nanofibers, a Taylor cone is formed at the tip of a syringe containing a polymer solution. A high voltage is applied to the syringe, causing the solution to form a Taylor cone and eject a jet of polymer. As the solvent evaporates, it leaves behind a fiber that can be collected on a grounded target.