Particle clustering during pearl chain formation in a conductive-island based dielectrophoretic assembly system

Abstract

A dielectrophoretically (DEP) assembled metal nanoparticle chain can serve as an electrical connector between small conductive elements in wet electronics or as a sensing element for chemical and biological substances. Obviously, the morphology of the nanoparticle assembled chain has a strong influence on electrical conductance and surface area of this connector. This paper presents an experimental discovery that as a connection of the electrode pair to an initially isolated conductive island is formed by the assembled nanoparticle chain, an abundance of particle clusters can also be generated, which tend to accumulate on the edge of the conductive structures under certain conditions. These particle clusters either can have an undesirable impact on consistency in electrical conductance of the electric circuit or can be used to enhance the susceptibility of the sensors due to an increased surface area. Therefore, exploration is also made for manipulating and assembling metallic nanoparticles on the surface or edge of a conductive island by changing the AC frequency in the conductive island based DEP assembly system. In order to develop an explanation of the experimental observations, numerical simulation is performed to investigate the combined influence of DEP force and electrothermal flow on individual nanoparticles by taking account of the near-field effect due to particle-solid interaction or particle-particle interaction.

Artificial Intelligence Algorithms Enable Automated Characterization of the Positive and Negative Dielectrophoretic Ranges of Applied Frequency

“…Previous research has established that, in addition to DEP and EO force, particles within an applied non-uniform electric field experience bead-to-bead attraction and form what is known as “pearl chains,” which align along the electric field lines [ 31 ]. These pearl chains can be seen within the individual still-frame images, such as Figure 12 below.…”

Directed Assembly of Nanomaterials for Making Nanoscale Devices and Structures: Mechanisms and Applications

“…One application of the DEP phenomenon is the assembly of various nanoparticles (metallic or semiconducting , ) between two planar electrodes into pearl chains or micro/nanowires. , As a consequence of the fringing field effect, the electric field strength is always high in the vicinity of the electrode edges . Under a positive DEP force, nanoparticles assemble simultaneously from the opposing electrode edges with the highest electric field intensity and finally meet at the center of the electrode gap, forming a pearl chain structure (Figure b). , Two mechanisms may contribute to the formation of the pearl chain: (i) nanoparticles chain together away from the electrodes under a pearl-chaining force and then move toward the electrodes due to the DEP force, and (ii) nanoparticles assemble directly at the electrodes under the DEP force and then continually assemble at the front tip of the growing chain .…”

Assembly of 1D Granular Structures from Sulfonated Polystyrene Microparticles

“…Field-assisted organization of 1D colloidal and granular particles usually takes place in a solution [ 25 , 26 ] or at liquid interfaces [ 27 , 28 ]. Recently, we reported a route to fabricating particle chain-like structures outside liquid environments [ 29 ].…”