Described herein are cartridges and devices for operating said cartridges for analyzing a biological sample, such as a blood or saliva sample. Also described herein is an impedance sensor for analyzing a biological sample. Further described herein are methods of determining a cell count or detecting an analyte in a biological sample, which can include transporting the biological sample through a sensor comprising a channel or pore; applying an electrical current or voltage to the channel or pore; detecting an impedance within the channel or pore; and determining a cell count or detecting the analyte based on the detected impedance. Also described herein is an electrowetting electrode array that is configured to transport aqueous solutions using low voltage, such as about 50 volts or less. Further described herein are methods of transporting an aqueous liquid using electrowetting electrodes.

An electromagnetic flowmeter and a method for measuring a property of a fluid composition are provided. The electromagnetic flowmeter includes a first electric conductor with first and second ends, arranged inside a fluid conduit carrying a fluid composition comprising hydrocarbons, an RF electric signal source, and a first dual signal detector including first and second input ports. The first terminal of the electric signal source is connected to the first end of the first electric conductor and arranged to induce an RF electromagnetic wave in the fluid conduit by supplying an input electric signal to the first end of the first electric conductor. The first and second ports of the signal detector are connected to the first and second ends of the first electric conductor, respectively.

A system to measure a streaming potential of a core plug includes a measurement cell having a chamber to hold the core plug and an inlet fluid line connected to an inlet port of the measurement cell. A filtration device is arranged to control a salinity and ionic strength of a liquid medium received in the chamber through the inlet fluid line. The filtration device has membrane filters with different ion rejection rates and is controllable to selectively dispose each of the membrane filters in the inlet fluid line.

A system to measure a streaming potential of a core plug includes a measurement cell having a chamber to hold the core plug and an inlet fluid line connected to an inlet port of the measurement cell. A filtration device is arranged to control a salinity and ionic strength of a liquid medium received in the chamber through the inlet fluid line. The filtration device has membrane filters with different ion rejection rates and is controllable to selectively dispose each of the membrane filters in the inlet fluid line.

Numerous embodiments of a bubble detection apparatus and method are disclosed. In one embodiment, a bubble detection module is placed into a liquid to be monitored. The module comprises a physical structure housing a nanowire sensing element. The liquid flows through the physical structure. An electric bias is placed across the nanowire sensing element, and the resistance of the nanowire sensing element changes when a bubble is in contact with the element. A change in voltage or current of the bias signal can be measured to identify the exact instances when a bubble is in contact with the nanowire sensing element.

Various embodiments are directed to a fluid composition sensor device and method of using the same. In various embodiments, the fluid flow composition sensor is configured to receive a volume of fluid, the fluid composition sensor comprising a housing, a removable fluid flow component, an impactor nozzle, a collection media assembly dock element configured to receive a replaceable collection media assembly comprising a collection media configured to receive one or more particles within the volume of fluid, an imaging device configured to capture an image of at least a portion of the one or more particles received by the fluid composition sensor, and a controller configured to determine, based at least in part on the image, at least one particle characteristic of the volume of fluid. The imaging device may be configured to capture the image of one or more particles received by the fluid composition sensor using lensless holography.

A circuit for measuring the conductivity of a medical fluid, the circuit comprising: a data collecting cell through which a medical fluid is configured to flow; an input voltage source that provides an input voltage to the data collecting cell; a voltage measurement unit configured to measure the input voltage and an output voltage of the data collecting cell; and a switch in communication with the voltage measurement unit, the switch configured to switch between a first state in which the voltage measurement unit is configured to measure the input voltage and a second state in which the voltage measurement unit is configured to measure the output voltage of the data collecting cell.

A method for determining conductivity of a medium includes: generating a signal with first and second frequencies; feeding the signal to first and second electrodes; determining a first voltage between the first and second electrodes, a first current through the medium for the first frequency, and a first impedance from the first voltage and first current; determining a second voltage between the first and second electrodes, a second current through the medium for the second frequency, and a second impedance from the second voltage and second current; determining and comparing phases of the first and second impedances; determining a medium resistance with a first formula when the first impedance phase is smaller than the second impedance phase; determining a medium resistance with a second formula when the first impedance phase is equal to or greater than the second impedance phase; and determining conductivity of the medium using the medium resistance.

A method for determining conductivity of a medium includes: generating a signal with first and second frequencies; feeding the signal to first and second electrodes; determining a first voltage between the first and second electrodes, a first current through the medium for the first frequency, and a first impedance from the first voltage and first current; determining a second voltage between the first and second electrodes, a second current through the medium for the second frequency, and a second impedance from the second voltage and second current; determining and comparing phases of the first and second impedances; determining a medium resistance with a first formula when the first impedance phase is smaller than the second impedance phase; determining a medium resistance with a second formula when the first impedance phase is equal to or greater than the second impedance phase; and determining conductivity of the medium using the medium resistance.

An electrode assembly for a conductivity meter or resistivity meter includes: an electrode main body; a test liquid intake flow path passing through the electrode main body; a pair of voltage electrodes which is respectively provided so that surfaces thereof are exposed to opposing inner wall surfaces forming the test liquid intake flow path; and a pair of current electrodes which is respectively provided so that surfaces thereof are exposed to each of the inner wall surfaces, and in this configuration, each of the pair of current electrodes contains a carbon-based material, and each of the surfaces of the pair of current electrodes exposed to the inner wall surfaces is in a strip shape.