Methods and systems for processing polynucleotides (e.g., DNA) are disclosed. A processing region includes one or more surfaces (e.g., particle surfaces) modified with ligands that retain polynucleotides under a first set of conditions (e.g., temperature and pH) and release the polynucleotides under a second set of conditions (e.g., higher temperature and/or more basic pH). The processing region can be used to, for example, concentrate polynucleotides of a sample and/or separate inhibitors of amplification reactions from the polynucleotides. Microfluidic devices with a processing region are disclosed.

A device including a microfluidic channel structure formed on a substrate and including a first channel and a fluid actuator within the microfluidic channel structure. A sense region within the first channel is to receive a fluid flow of target biologic particles for counting in a single file pattern, with the sense region having a volume on a same order of magnitude as a volume of a single one of the target biologic particles.

A data receiver thread is continuously executed to receive in which signals indicating a fluid parameter. A predetermined time quantity of the signals is repeatedly buffered. Upon completion of the buffering of each predetermined time quantity of the signals, a data processing thread is initiated that executes on the just completed buffered predetermined time quantity of signals. Upon completion of each data processing thread, data from the just completed data processing thread is passed to a data plotting thread. Results of the data plotting thread are displayed on a portable electronic device while the data receiver thread is being executed.

A microfluidic diagnostic chip may comprise a main fluid channel comprising a main pump, a secondary fluid channel branching off from the main fluid channel, and a secondary pump within the secondary fluid channel wherein the secondary pump is to pull a particle of analyte of a first size from a fluid passing through the main channel, the fluid comprising particles of analyte of the first size and of a number of larger sizes. A method of analyzing an analyte on a microfluidic chip may comprise pumping, with a main microfluidic pump, a fluid comprising an analyte particle through a main microfluidic channel fluidly coupled to a fluid slot and sorting the analyte particle within the fluid through a secondary microfluidic channel by pulling the analyte particle into the secondary microfluidic channel with a secondary microfluidic pump.

Fluid may be pumped within a microfluidic channel across a cell/particle sensor using a microscopic resistor. The microscopic resistor may be selectively actuated so as to heat the fluid within the microfluidic channel to a temperature below a nucleation energy of the fluid so as to regulate a temperature of the fluid for at least when the cell/particle sensor is sensing the fluid.

In example implementations, an apparatus is provided. The apparatus includes a channel, an opening in the channel, and a heating element aligned with the opening on opposite sides of the channel. The channel contains a droplet of a first liquid containing a particle, wherein the droplet is carried within a second liquid in the channel. The heating element is to heat the first liquid to generate a vapor in the first liquid to eject the droplet of the first liquid through the opening.

Methods for selectively adding one or more reagents are provided. In certain aspects, the methods include selectively merging one or more droplets of a plurality of droplets with one or more droplets of a plurality of reagent droplets based on detection of a property. Systems, devices and kits for practicing the subject methods are also provided. The subject disclosure may find use in a wide variety of applications, such as increasing the accuracy and/or efficiency of single-cell sequencing, detection of cancer or other diseases, monitoring disease progression, analyzing the DNA or RNA content of cells, and other applications in which it is desired to detect and/or quantify specific target cells.

In one example in accordance with the present disclosure, a fluid ejection die is described. The fluid ejection die includes a fluid feed slot to deliver fluid from a reservoir to an array of ejection chambers fluid connected to the fluid feed slot. Each ejection chamber includes at least one fluid actuator and an opening through which fluid is to be ejected. The fluid ejection die also includes a number of antechambers. An antechamber includes sidewalls that curve inward.

Examples herein provide a device. The device includes a sample delivery component, which includes: a reagent chamber to contain at least one reagent; a sample chamber to contain a fluid sample; and a delivery channel extending from the reagent chamber and in fluid communication with the sample chamber and an output port, wherein the delivery channel is conducive mixing the at least one reagent and the fluid sample to form a mixture before the mixture reaches the output port and be discharged therefrom. The device includes a testing cassette detachable from the delivery component, which includes: an input port in fluid communication with a microfluidic reservoir, the input port to receive the discharged fluid sample from the output port; and a micro-fabricated integrated sensor in a microfluidic channel extending from the microfluidic reservoir.

A microfluidic valve may include a first portion of a liquid conduit to contain a gas, a second portion of a liquid conduit to contain a liquid, and a constriction between the first portion and the second portion and across which a capillary meniscus is to form between the gas and the liquid. The microfluidic valve may further include a drop jetting device within the second portion to open the valve by breaking the capillary meniscus across the constriction.