Methods are provided for separating magnetically responsive beads from a droplet in a droplet actuator. Droplet operations electrodes and a magnet are arranged in a droplet actuator to manipulate a bead-containing droplet and position it relative to a magnetic field region that attracts the magnetically responsive beads. The droplet operations electrodes are operated to control the droplet shape and transport it away from the magnetic field region to form a concentration of beads in the droplet. The continued transport of the droplet away from the magnetic field causes the concentration of beads to break away from the droplet to yield a small, concentrated bead-containing droplet immobilized by the magnet.

Individual biological cells can be selected in a micro-fluidic device and moved into isolation pens in the device. The cells can then be lysed in the pens, releasing nucleic acid material, which can be captured by one or more capture objects in the pens. The capture objects with the captured nucleic acid material can then be removed from the pens. The capture objects can include unique identifiers, allowing each capture object to be correlated to the individual cell from which the nucleic acid material captured by the object originated.

The present invention discloses a nanoparticle control and detection system and operating method thereof. The present invention controls and detects the nanoparticles in the same device. The device comprises a first transparent electrode, a photoconductive layer, a spacer which is deposed on the edge of the photoconductive layer and a second transparent electrode. The aforementioned device controls and detects the nanoparticles by applying AC/DC bias and AC/DC light source to the transparent electrode.

A fluidic apparatus for detection of a chemical substance, a biosensor, and a method of fabricating the fluidic apparatus. The fluidic apparatus includes a fluidic structure arranged to receive a sample containing a target substance, and a trapping structure, in fluid communication with the fluidic structure and arranged to immobilize the target substance in a detection region, wherein the detection region of the trapping structure is arranged to alter a physical characteristic of an incident light signal which represents a concentration of the target substance contained in the sample.

A counting method includes aggregating particles in a sample by the action of first dielectrophoretic force, dispersing the aggregated particles by the action of second dielectrophoretic force, which is different from the first dielectrophoretic force, capturing a dispersion image including the dispersed particles, and determining the number of particles on the basis of the dispersion image.

Methods of selectively positioning a micro-object in a microfluidic device are described in this application. The microfluidic device can comprise an enclosure having an inlet, an outlet, and a flow region connecting the inlet and outlet, and an electrode activation substrate having a photoconductive layer. The methods of selectively positioning can comprising: projecting a first light beam on an electrode activation substrate of the microfluidic device, wherein the first position is proximal to the first micro-object, and wherein the first light beam activates a positive dielectrophoresis (DEP) force within the enclosure sufficient to capture the first micro-object; and projecting a second light beam upon a second position on the electrode activation substrate, wherein the second position is adjacent to or at least partially surrounding the first position, without overlapping the first position, the second light beam activating a positive DEP force within the enclosure sufficient to capture second micro-objects other than the first micro-object. The methods of selectively positioning can further comprise moving the first light beam towards a third position on the electrode activation substrate, wherein the DEP force activated by the first light beam is sufficient to move the first micro-object to the third position. Optionally, the methods can include moving the second light beam in relation to the first light beam to prevent micro-objects other than the first micro-object from being captured by the first light beam. Other embodiments are described.

Methods are provided for separating magnetically responsive beads from a droplet in a droplet actuator. Droplet operations electrodes and a magnet are arranged in a droplet actuator to manipulate a bead-containing droplet and position it relative to a magnetic field region that attracts the magnetically responsive beads. The droplet operations electrodes are operated to control the droplet shape and transport it away from the magnetic field region to form a concentration of beads in the droplet. The continued transport of the droplet away from the magnetic field causes the concentration of beads to break away from the droplet to yield a small, concentrated bead-containing droplet immobilized by the magnet.

For some examples, an apparatus to effect particle separation may include a dielectrophoretic particle separator that may separate particles within a focused particle stream. The dielectrophoretic particle separator may apply an electric field to the particles. An imaging system may capture images of the particles passing through a separation region of the dielectrophoretic particle separator. An image processing and control system may process the images to obtain information regarding the particles and may adjust an operating parameter of the dielectrophoretic separator based upon the information regarding the particles.

A microfluidic device can include a base an outer surface of which forms one or more enclosures for containing a fluidic medium. The base can include an array of individually controllable transistor structures each of which can comprise both a lateral transistor and a vertical transistor. The transistor structures can be light activated, and the lateral and vertical transistors can thus be photo transistors. Each transistor structure can be activated to create a temporary electrical connection from a region of the outer surface of the base (and thus fluidic medium in the enclosure) to a common electrical conductor. The temporary electrical connection can induce a localized electrokinetic force generally at the region, which can be sufficiently strong to move a nearby micro-object in the enclosure.

There is provided an impedance sensor capable of counting the number of microscopic biological materials and specifying their properties stably with high sensitivity. An impedance sensor includes a measuring electrode pair formed at a wiring layer in a multilayer-wiring circuit board and one or more dielectrophoresis electrodes formed at another wiring layer lower than the wiring layer.