Methods for on-demand printing discrete entities including, e.g., cells, media or reagents to substrates are provided. In certain aspects, the methods include manipulating qualities of the entities or biological components thereof. In some embodiments, the methods may be used to create arrays of microenvironments and/or for two and three-dimensional printing of tissues or structures and/or for in situ printing for microsurgeries. Systems and devices for practicing the subject methods are also provided.

Microfluidic devices and systems are provided. Methods for conducting immune assays with the devices and systems are also provided.

A cartridge, in particular a disposable cartridge, for use in an electrowetting sample processing system. The cartridge contains an internal gap with at least one hydrophobic surface for enabling an electrowetting induced movement of a microfluidic droplet that has magnetic beads and further has a bead accumulation zone, into which the microfluidic droplet is transferable by electrowetting force and the magnetic beads are exposable to a magnetic force of a bead manipulation magnet. The internal gap has a bead extraction opening adjacent to the bead accumulation zone. The bead extraction opening provides a passage from the gap to an exterior space of the cartridge and is configured to removably receive the bead manipulation magnet for enabling an extraction of the magnetic beads from the microfluidic droplet by a removal of the bead manipulation magnet.

Described are microparticle fractionating apparatus and methods of fractionating microparticles. Multiple electrodes may be used to charge droplets when separating and collecting microparticles based on a result analyzed by an optical methodologies. A first electrode may be used to charge a sample fluid, and a second electrode used to apply additional charge near a droplet break-off point.

The present disclosure provides “all-in-one” cartridges which contain necessary reagents and materials to isolate/preconcentrate targeted proteins from blood plasma and ionize them for mass spectrometry detection. In another configuration, the cartridges include proteolytic enzymes to digest the proteins into smaller peptides in addition to preconcentration and ionization for mass spectrometry detection.

A pipette based on surface charges includes a pipette body. A plurality of support rods are provided below the pipette body. Connecting rods are provided at the lower ends of two adjacent support rods. A substrate is provided between the connecting rods. A porous SiO.sub.2 coating is provided on the substrate. A hydrophobic molecule layer is provided on the surface coating by the vapor deposition method. A superamphiphobic surface is formed on the substrate by the surface coating and the hydrophobic molecule layer. The substrate and the surface coating are made of dielectric materials. A circular limit plate is provided above the pipette body. The pipette body, the support rods, the connecting rods and the limit plate are integrally formed, and are electrically non-conductive. An electrically conductive sliding rod is movably provided within the pipette body and the limit plate.

A cartridge, in particular a disposable cartridge, for use in an electrowetting sample processing system. The cartridge contains an internal gap with at least one hydrophobic surface for enabling an electrowetting induced movement of a microfluidic droplet that has magnetic beads and further has a bead accumulation zone, into which the microfluidic droplet is transferable by electrowetting force and the magnetic beads are exposable to a magnetic force of a bead manipulation magnet. The internal gap has a bead extraction opening adjacent to the bead accumulation zone. The bead extraction opening provides a passage from the gap to an exterior space of the cartridge and is configured to removably receive the bead manipulation magnet for enabling an extraction of the magnetic beads from the microfluidic droplet by a removal of the bead manipulation magnet.

Provided is a substance mixing apparatus including two or more flow paths in which orifices, from which a fluid that flows therethrough is externally discharged, are formed, oscillation devices that form droplets of the fluid discharged from each of the orifices by oscillating at least the orifice part of the flow paths at a predetermined oscillation frequency and discharge the droplets, and means for causing the droplets discharged from the orifices of the flow paths to collide with one another.

A microfluidic device includes a substrate, a sensor, and one or more lamination films. The top surface of the substrate can include first recessed grooves forming first open channels and the bottom surface of the plastic substrate can include a first recessed cavity and second recessed groves forming second open channels. A first lamination film can be adhered with the top surface of the plastic substrate to form first closed channels. A second lamination film can be adhered to the bottom surface of the plastic substrate to form second closed channels. The sensor can be on the bottom surface of the substrate such that it overlies the first recessed cavity to form a flow cell with the sensor top surface inward facing. A first closed channel can be fluidically connected with a second closed channel and a first or second closed channel can be fluidically connected with the flow cell.

A method of analysing a skin-print comprising the steps of providing a porous substrate, the porous substrate extending in a substrate plane and being substantially planar and having a first end and a second end, wherein the second end tapers to a point. The method further comprises: applying to the porous substrate a skin-print to be analysed; applying a fluid to the porous substrate; applying a voltage between the first end of the porous substrate and ground to generate an electric field, by which droplets of the fluid are ionised and emitted from the point in the form of a Taylor cone; and analysing the ionised droplets using a mass spectrometer.