title: Three dimensional passivated-electrode insulator-based dielectrophoresis.
abstract: In this study, a 3D passivated-electrode, insulator-based dielectrophoresis microchip (3D πDEP) is presented. This technology combines the benefits of electrode-based DEP, insulator-based DEP, and three dimensional insulating features with the goal of improving trapping efficiency of biological species at low applied signals and fostering wide frequency range operation of the microfluidic device. The 3D πDEP chips were fabricated by making 3D structures in silicon using reactive ion etching. The reusable electrodes are deposited on second glass substrate and then aligned to the microfluidic channel to capacitively couple the electric signal through a 100 μm glass slide. The 3D insulating structures generate high electric field gradients, which ultimately increases the DEP force. To demonstrate the capabilities of 3D πDEP, Staphylococcus aureus was trapped from water samples under varied electrical environments. Trapping efficiencies of 100% were obtained at flow rates as high as 350 μl/h and 70% at flow rates as high as 750 μl/h. Additionally, for live bacteria samples, 100% trapping was demonstrated over a wide frequency range from 50 to 400 kHz with an amplitude applied signal of 200 Vpp. 20% trapping of bacteria was observed at applied voltages as low as 50 Vpp. We demonstrate selective trapping of live and dead bacteria at frequencies ranging from 30 to 60 kHz at 400 Vpp with over 90% of the live bacteria trapped while most of the dead bacteria escape.
authors.affiliation: VT MEMS - Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24060 , USA.
authors.forename: Diana
authors.initials: D
authors.lastname: Nakidde
authors.affiliation: VT MEMS - Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24060 , USA.
authors.forename: Phillip
authors.initials: P
authors.lastname: Zellner
authors.forename: Mohammad Mehdi
authors.identifier: 0000-0002-4257-3566
authors.initials: MM
authors.lastname: Alemi
authors.affiliation: VT MEMS - Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24060 , USA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Shake
authors.affiliation: VT MEMS - Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24060 , USA.
authors.forename: Yahya
authors.identifier: 0000-0002-7866-235X
authors.initials: Y
authors.lastname: Hosseini
authors.affiliation: Pruden Lab - Department of Civil and Environmental Engineering , Virginia Tech, Blacksburg, Virginia 24060, USA.
authors.forename: Maria V
authors.initials: MV
authors.lastname: Riquelme
authors.affiliation: Pruden Lab - Department of Civil and Environmental Engineering , Virginia Tech, Blacksburg, Virginia 24060, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Pruden
authors.affiliation: VT MEMS - Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24060 , USA.
authors.forename: Masoud
authors.initials: M
authors.lastname: Agah