Automated detection of particle concentration and chemical reactions in EWOD devices

Dimensionless model for impedimetric sensing of particle laden droplets in digital microfluidic devices

“…Chemical reactions can then take place as particles are introduced to a variety of reagents. In some cases, these reactions can change the dielectric coefficient or resistivity of the carrier fluid (Sadeghi et al 2012;Schertzer et al 2012). Here, the spectrum of impedance over a range of measurement frequencies can be used to monitor the reaction.…”

“…In order to manipulate droplets in DMF devices, the droplet must be grounded and at least a portion of the contact line of the interface must be above the active electrode (Mugele and Baret 2005;Nelson and Kim 2012;Choi et al 2012). In the most common configuration, each addressable location in the device can be modeled as a resistor and capacitor in parallel (Lederer et al 2012;Sadeghi et al 2012;Schertzer et al 2012;Shih et al 2013). As such, previous investigations have used capacitance (Su et al 2004;Ren et al 2004;Su et al 2005;Gong and Kim 2008;Shih et al 2011;Yafia and Najjaran 2013) and impedance (Lederer et al 2012;Sadeghi et al 2012;Schertzer et al 2012;Shih et al 2013) measurements to provide real-time feedback at every addressable position in the device without requiring optical access, or increasing fabrication complexity.…”

“…In the most common configuration, each addressable location in the device can be modeled as a resistor and capacitor in parallel (Lederer et al 2012;Sadeghi et al 2012;Schertzer et al 2012;Shih et al 2013). As such, previous investigations have used capacitance (Su et al 2004;Ren et al 2004;Su et al 2005;Gong and Kim 2008;Shih et al 2011;Yafia and Najjaran 2013) and impedance (Lederer et al 2012;Sadeghi et al 2012;Schertzer et al 2012;Shih et al 2013) measurements to provide real-time feedback at every addressable position in the device without requiring optical access, or increasing fabrication complexity. The majority of capacitive detection techniques in DMF devices measure void fraction to monitor the health of the device (Su et al 2004Ren et al 2004Gong and Kim 2008;Shih et al 2011;Yafia and Najjaran 2013).…”

“…This technique was enhanced by including resistive and capacitive components of impedance to measure the presence and composition of particle free droplets in DMF devices (Lederer et al 2012;Sadeghi et al 2012). Experimental results show that impedimetric feedback can also be used to monitor chemical reactions (Lederer et al 2012;Schertzer et al 2012), particle concentration (Schertzer et al 2012), and cell cultures (Shih et al 2013) in DMF devices. While these works demonstrate the suitability of real-time electrical feedback in particle laden droplets, a general model for the impedimetric response of these systems has not yet been developed.…”

Stationary-Mixing Field-Programmable Pin-Constrained Digital Microfluidic Biochip

“…For example, input and output (including waste production) use reservoirs that are physically placed on the perimeter of the chip; the locations and roles of the reservoirs do not change when the DMFB is in use, so they are not reconfigurable. External devices such as sensors, mixers, and heaters may be placed at any location on the chip surface [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]; such locations can still perform the five basic operations, but are now enhanced with additional capabilities. Similarly, specialized electrodes can be fabricated to perform operations such as electroporation [12] or non-uniform splitting [32].…”