In situ digital microfluidic conductance sampling

Nichols, Jacqueline; Ahmadi, Ali; Hoorfar, Mina; Najjaran, Homayoun; Holzman, Jonathan F.

doi:10.1016/j.sna.2009.03.013

Cited by 4 publications

(1 citation statement)

References 30 publications

(43 reference statements)

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“…One possibility is to use an optical detection, and either rely on additional fluorescence marker or other particles acting as indicators [9,10], or to measure the difference in laser absorption [11]. In the field of electric sensing, first studies reporting droplet sensing [12][13][14] were focused on digital microfluidics [15]. Cahill first reported the electric sensing of a slug flow [16]; he and his forgoers used capacitively coupled measurement.…”

Section: Introductionmentioning

confidence: 99%

AC electric sensing of slug-flow properties with exposed gold microelectrodes

Janouš

Čech

Beránek

et al. 2013

J. Micromech. Microeng.

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A new method for slug-flow (segmented flow) characterization by means of ac electric sensing is proposed. Water segments regularly dispersed in kerosene are used as an experimental system. The sensing procedure is carried out in a plexiglass microchip with embedded gold microelectrodes. The presence of passing slugs over a measurement spot is determined from impedance variations. A square-shaped signal resulting from the slug flow is acquired and flow properties such as the mean velocity and length of the slugs are calculated. Complex behaviour of the corresponding electrochemical system is studied. Dependence of the impedance signal on the flow rate, ion concentration in the dispersed water slug and electric field strength are discussed and explained in detail. Advantages and disadvantages of the suggested method, in comparison with existing capacitive noncontact methods, are also clarified. Unlike the noncontact methods of electric sensing, with the insulation dielectric layer over the electrodes, our electrodes are in a direct contact with the carrier phase. The results show that the method is promising for process applications and will be further improved.

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