Exosomes are a specific subpopulation of extracellular vesicles that have gained interest because of their many potential biomedical applications. However, exosome isolation and characterization are the first steps toward designing novel applications. Researchers at the Tecnologico de Monterrey have developed a direct current-insulator-based dielectrophoretic (DC-iDEP) approach to simultaneously capture and separate exosomes by size. To do so, a microdevice consisting of a channel with two electrically insulating post sections was designed. Each section was tailored to generate different nonuniform spatial distributions of the electric field and, therefore, different dielectrophoretic forces acting on exosomes suspended in solution. Side channels were placed adjacent to each section to allow sample recovery. By applying an electric potential difference of 2000 V across the length of the main channel, dielectrophoretic size-based separation of exosomes was observed in the device. Analysis of particle size in each recovered fraction served to assess exosome separation efficiency. These findings show that iDEP can represent a first step toward designing a high-throughput, fast, and robust microdevice capable of capturing and discriminating different subpopulations of exosomes based on their size.
Numerical simulations showing the distribution and magnitude of ∇(𝐸⃗ ∙ 𝐸⃗ ) in both sections, obtained by applying DC voltages of 1500 V and 2000 V
(A) Field gradient spatial distribution in the vicinity of gaps between PDMS posts in the first and second section when applying voltages of 1500 V and 2000 V. (B) Cut lines in sections 1 and 2 for more detailed analysis of the field gradient magnitude. (C) Distribution of ∇(𝐸⃗ ∙ 𝐸⃗ ) achieved between the electrically insulating posts of both sections when a DC electric potential difference of 1500 V was applied across the main channel. (D) Distribution of ∇(𝐸⃗ ∙ 𝐸⃗ ) achieved between the electrically-insulating posts of both sections when a DC electric potential difference of 2000 V was applied across the main channel.