Loading a High-Viscous Droplet via the Cone-Shaped Liquid Bridge Induced by an Electrostatic Force

Abstract

In transfer printing, the loaded droplet on the probe has a significant influence on the dispensing resolution. A suitable loading approach for a high-viscous liquid is highly required. Herein, a novel electrostatic loading method is presented, in which the main aim is to control precisely the formation and breaking of a cone-shaped liquid bridge. An experimental device is developed. The influence of electrical and geometric parameters on the feature size of the liquid bridge is investigated in detail. In the formation of the liquid bridge, the increase of voltage or the decrease of the air gap can enhance the electric field intensity, thus reducing the formation period and increasing the initial cone tip diameter of the liquid cone. After the liquid bridge is formed, both the circuit current implying the liquid wetted area on the probe surface and the lifting velocity of the probe are utilized to further regulate the volume of the loaded droplet. Loaded droplets ranging from 60 to 600 pL are obtained via the method with a standard deviation of 4 to 30 pL. Moreover, a dot array is transferred with different loaded droplets. The minimum diameter of the printed dots is about 140 μm with a variation less than 5%. The advantages include the reduced risk of contamination, the droplet-size independent of the size of the probe, and the low cost of the device.

Polarization Effect and Improvement of the Electroinduced Formation Efficiency of a Highly Viscous Liquid Bridge

“…25 The dipole is assumed to be an ellipsoid with axis length l i = {a, b, c} and rotates about the c-axis to θ = 0, where θ is the angle between the electric field and the a-axis, as shown in Figure 4c. Two characteristic parameters of the ellipsoidal dipole are given by the elliptic integrals (4) (5) The polarization intensity of the ellipsoidal dipole can be expressed as (6) where ε p and ε m are the dielectric constants of the particles and medium, E i is the component of electric field strength, and the denominator is replaced with k i in order to simplify the formula.…”

“…However, its main disadvantages are the relatively low efficiency and weak stability of the loading period. As the electroinduced formation of a liquid bridge is from 30−240 s for a highly viscous liquid suspension, 5 it is urgent to find out the reason and then shorten the time of electroinduced formation.…”

Stretching breakup of a conical liquid bridge with a moving contact line

“…One is to dip the probe directly into the reservoir, whereby the liquid climbs along the sidewall of the probe, forming a conical liquid bridge as it is withdrawn. The other is based on our previously proposed electrically induced liquid loading method, 6 where electrostatic force drives the liquid upward to form a conical liquid bridge. Compared to dipping, the liquid actively wets the probe and the bridge top is independent of probe size.…”

Study on the Formation and Controllable Movement of Polymer Liquid Columns Based on Dynamic Control of Spatial Electric Field Distribution

“…The control of liquid deformation and motion is a key technology in modern chemistry, biology, and medicine. , Especially in the fabrication of microelectromechanical systems (MEMS) and microelectronic devices, some polymer liquids are widely used for multipart assembly, encapsulation, etc. For example, the formation of dielectric fluid can be transferred to produce a polydimethylsiloxane (PDMS) stamp, which is a key element of soft lithography .…”