Abstract: This disclosure relates to methods and devices to count particles of interest, such as cells. The methods include obtaining a fluid sample that may contain particles of interest; counting all types of particles in a portion of the sample using a first electrical differential counter to generate a first total; removing any particles of interest from the portion of the fluid sample; counting any particles remaining in the portion of the fluid sample using a second electrical differential counter after the particles of interest are removed to generate a second total; and calculating a number of particles of interest originally in the fluid sample by subtracting the second total from the first total, wherein the difference is the number of particles of interest in the sample. These methods and related devices can be used, for example, to produce a robust, inexpensive diagnostic kit for CD4+ T cell counting in whole blood samples.

Abstract: This disclosure relates to methods and devices to count particles of interest, such as cells. The methods include obtaining a fluid sample that may contain particles of interest; counting all types of particles in a portion of the sample using a first electrical differential counter to generate a first total; removing any particles of interest from the portion of the fluid sample; counting any particles remaining in the portion of the fluid sample using a second electrical differential counter after the particles of interest are removed to generate a second total; and calculating a number of particles of interest originally in the fluid sample by subtracting the second total from the first total, wherein the difference is the number of particles of interest in the sample. These methods and related devices can be used, for example, to produce a robust, inexpensive diagnostic kit for CD4+ T cell counting in whole blood samples.

Abstract: This document provides methods and devices for metering fluids. In some cases, the methods and devices include intersecting channels that include capillary-stop geometries at each intersection point that guides the fluids on a desired path, which is controlled by the opening and closing of valves. For example, a metering channel can intersect a loading channel and intersect an outflow channel and a metering portion can be defined by the geometry of the metering channel between the intersection points.

Abstract: This document provides methods and devices for metering fluids. In some cases, the methods and devices include intersecting channels that include capillary-stop geometries at each intersection point that guides the fluids on a desired path, which is controlled by the opening and closing of valves. For example, a metering channel can intersect a loading channel and intersect an outflow channel and a metering portion can be defined by the geometry of the metering channel between the intersection points.

Abstract: This document provides devices, systems, and methods for delivering fluids. In some cases, the devices, systems, and methods include a deformable reservoir being at least partially defined by rigid plastically-deformable web. An actuator can press against said rigid plastically-deformable web to plastically deform said web. In some cases, a controller is adapted to receive a cartridge including a deformable reservoir and control the pressing of an actuator against a rigid plastically-deformable web to deliver fluid from the deformable reservoir.

Abstract: Methods for determining and/or quantifying one or more analytes in fluids are generally provided. In some embodiments, a method comprises introducing or exposing a plurality of conjugated capture structures and a plurality of metal-containing (e.g., silver) conjugated particles to a fluid comprising the analyte such that the analyte binds with both a capture structure and a metal-containing (e.g., silver) particle to form a bound complex. The bound complex may then be subjected to conditions (e.g., electrochemical conditions) that allow quantification of the analyte based on the amount of metal-containing particles present. The methods described herein may be useful for determining and quantifying relatively low concentrations of analytes present in a patient sample (e.g., a droplet of whole blood).

Abstract: This document provides devices, systems, and methods for delivering fluids. In some cases, the devices, systems, and methods include a deformable reservoir being at least partially defined by rigid plastically-deformable web. An actuator can press against said rigid plastically-deformable web to plastically deform said web. In some cases, a controller is adapted to receive a cartridge including a deformable reservoir and control the pressing of an actuator against a rigid plastically-deformable web to deliver fluid from the deformable reservoir.

Abstract: This document provides conductive patterns, electrical sensors including conductive patterns, and methods of making conductive patterns used in electrical sensors. In some cases, the conductive patterns can define one or more microelectrodes. For example, thermal transfer printing techniques are described. In some cases, a microfluidics device can include one or more microelectrodes in a micro-channel.

Abstract: This document provides conductive patterns, electrical sensors including conductive patterns, and methods of making conductive patterns used in electrical sensors. In some cases, the conductive patterns can define one or more microelectrodes. For example, thermal transfer printing techniques are described. In some cases, a microfluidics device can include one or more microelectrodes in a micro-channel.