Electrowetting-based Digital Microfluidics Platform for Automated Enzyme-linked Immunosorbent Assay

Abstract

Electrowetting is the effect by which the contact angle of a droplet exposed to a surface charge is modified. Electrowetting-on-dielectric (EWOD) exploits the dielectric properties of thin insulator films to enhance the charge density and hence boost the electrowetting effect. The presence of charges results in an electrically induced spreading of the droplet which permits purposeful manipulation across a hydrophobic surface. Here, we demonstrate EWOD-based protocol for sample processing and detection of four categories of antigens, using an automated surface actuation platform, via two variations of an Enzyme-Linked Immunosorbent Assay (ELISA) methods. The ELISA is performed on magnetic beads with immobilized primary antibodies which can be selected to target a specific antigen. An antibody conjugated to HRP binds to the antigen and is mixed with H 2 O 2 /Luminol for quantification of the captured pathogens. Assay completion times of between 6 and 10 min were achieved, whilst minuscule volumes of reagents were utilized. Video Link The video component of this article can be found at https://www.jove.com/video/60489/ 15. Recently, in-field diagnostic against measles and rubella IgG has been demonstrated in remote Northwestern Kenya's

A perspective of active microfluidic platforms as an enabling tool for applications in other fields

“…The combination of the magnetic digital microfluidic platform with a heating source demonstrated the potential for genetic detection using PCR. The magnetic beads are particularly powerful as solid substrates for ELISA assays [169][170][171][172][173]; magnetic forces helps extract the bead while the standard EWOD platform handles fluid transport for example [174][175][176]. A similar approach combining the magnetic bead and forces with the EWOD droplet transport uses a surface enhanced Raman scattering-based immunoassay [177] and the optimization of thyroid-stimulating hormone immunoassays [178].…”

Fabrication of Transparent and Flexible Digital Microfluidics Devices

“…The substrate of the digital microfluidic device is of decisive significance for digital microfluidic devices. The substrate is usually made of glass or silicon material, with the electrodes (e.g., chromium, chromium, gold) fabricated with photolithography method [12,13], the dielectric layer is commonly fabricated with chemical vapor deposition of parlance or silicon nitride [14]. The glass/silicon-based digital microfluidics have high electrode patterns precision but are costly on materials and processing instruments.…”

Sensitivity Validation of EWOD Devices for Diagnosis of Early Mortality Syndrome (EMS) in Shrimp Using Colorimetric LAMP–XO Technique

“…To encourage more frequent use of the LAMP method and to ensure that reliable detection results and insignificant contamination are achieved in field test applications, lab-on-a-chip platforms (LOC), relying on various microfluidic techniques, have been applied and can be found in a variety of studies [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. Table 2 shows examples of successful applications of LOC platforms in chemical and biochemical detection.…”