Impedance-Based Sensing of Adherent Cells on A Digital Microfluidic Device

摘要

Devices and methods are provided for measuring, on a digital microfluidic platform, electrical signals associated with the impedance of adherent cells. In one embodiment, a sub-droplet of cell culture media containing adherent cells is passively dispensed at a pre-selected electrode location where a local hydrophilic surface region is provided, and adherent cells are attached to the local hydrophilic surface region. The cell culture media sub-droplet is replaced with a sub-droplet of a low-conductivity medium in a passive dispensing step, retaining the attached adherent cells. An AC voltage with a suitable frequency is applied between electrodes of the device and a signal associated with the impedance of the adherent cells is obtained. One of the electrodes to which the AC voltage is applied may be a dedicated sensing electrode. The local thickness of a dielectric layer coating the pre-selected electrode may be reduced to increase the detection sensitivity of the device.

主权项

1. A method of measuring an electrical signal associated with the presence of adherent cells on a digital microfluidic device;
the digital microfluidic device comprising:
a first plate comprising a first insulating substrate, an array of discrete electrodes formed on the first insulating substrate and a first dielectric layer provided on the discrete electrodes, wherein a surface of the first dielectric layer is hydrophobic;a second plate comprising a second insulating substrate at least one reference electrode formed on the second insulating substrate, and a second dielectric layer provided on the reference electrode, wherein a surface of the second dielectric layer is hydrophobic, wherein the second plate is provided in a spaced relationship relative to the first plate;wherein the digital microfluidic device includes a droplet of cell culture media located between the first plate and the second plate, the droplet of cell culture medium contacting a locally hydrophilic surface region that is proximal to a pre-selected discrete electrode of the array of discrete electrodes, wherein the locally hydrophilic surface region is comprises adherent cells attached thereto; the method comprising:
electrically actuating the digital microfluidic device to transport a droplet of low-conductivity medium to the pre-selected discrete electrode, wherein the electrical conductivity of the low-conductivity medium is lower than the electrical conductivity of the cell culture medium;electrically actuating the digital microfluidic device to passively dispense a sub-droplet of the low-conductivity medium, thereby displacing the droplet of cell culture medium; andapplying an AC voltage between the pre-selected discrete electrode and the reference electrode and measuring an electrical signal associated with the impedance of the adherent cells.