A system includes a container having an inner chamber for storing fluid, at least one measuring probe arranged within the chamber and one ground probe arranged within or near a bottom of the chamber. There is at least one impedance electrically connected with a processor which is electrically connected with the at least one measuring probe. A signal generator has a first voltage terminal electrically connected with the at least one impedance and a second voltage terminal electrically connected with the ground probe. When a signal is sent from the signal generator to the measuring probe, an electrochemical reaction occurs at the measuring probe and ground probe and stores a charge if the measuring probe and/or ground probe are immersed in fluid. The processor measures the voltage, current and power of the signal to calculate the resistance and capacitance of the fluid within the container to determine the level of fluid in the container. A method for measuring the level of fluid in the container includes the steps of applying at least one time-varying voltage signal to the one or more measuring probes, creating an electrochemical reaction between the ground probe and each measuring probe, storing energy around each probe that is submerged in fluid, measuring the current and power of the signals, and determining the level of fluid in the container based on the calculated capacitance and resistance of the fluid within the container.

Fluid containers having a volume marking(s) and conductive element(s) disposed at the volume marking(s) and a common conductive element are provided. For example, the fluid container has a wall forming the volume. The conductive element(s) and the common conductive element have a portion disposed within the volume and a portion external to the volume. The container further has a RFID tag, where the conductive element(s) and the common conductive element are connected thereto via respective conductive wires. A fluid detection system having the fluid containers is also provided. The system comprises one or more containers and a patient site monitor having a RF reader that interrogates the RFID tag at a preset interval. Responsive to the signal, the tag supplies a predetermined current to the conductive element and the common conductive element and detects a voltage and generates an alert based on the same.

A liquid reservoir includes at least one liquid surface level detection unit in the liquid reservoir. The at least one liquid surface level detection unit includes a plurality of liquid surface level detection units. The plurality of liquid surface level detection units each include a plurality of self-heating sensors. The plurality of self-heating sensors are positioned at different heights.

A field device electronics for a conductive, limit-level switch, with a conductive probe and a measuring circuit including a control/evaluation circuit. The measuring circuit, a measuring bridge circuit is present, with at least one coupling capacitor (C2) being present for the DC voltage separation of the probe from the measuring circuit, and with the at least one coupling capacitor (C2) being integrated into the measuring bridge circuit.

An electrode-type liquid level detection device comprises: an electrode unit in which at least two liquid level measurement electrodes, which are used to detect a liquid level, and a calibration electrode, which is not used to detect the liquid level, are integrated; a record unit that records a pre-use resistance value of each electrode of the electrode unit as initial resistance value; a calculation unit that calculates a resistance value of a to-be-measured object based on the initial resistance value; and a control unit that controls in such a way as to adjust a threshold value for determining whether or not the to-be-measured object exists, based on a change in resistance values of the at least two liquid level measurement electrodes when in use. Therefore, the liquid level can be accurately detected corresponding to deterioration of the instrument.

Fluid containers having a volume marking(s) and conductive element(s) disposed at the volume marking(s) and a common conductive element are provided. For example, the fluid container has a wall forming the volume. The conductive element(s) and the common conductive element have a portion disposed within the volume and a portion external to the volume. The container further has a RFID tag, where the conductive element(s) and the common conductive element are connected thereto via respective conductive wires. A fluid detection system having the fluid containers is also provided. The system comprises one or more containers and a patient site monitor having a RF reader that interrogates the RFID tag at a preset interval. Responsive to the signal, the tag supplies a predetermined current to the conductive element and the common conductive element and detects a voltage and generates an alert based on the same.

An apparatus and method for measuring the level of a liquid. The apparatus includes an elongated probe comprising an electrically and thermally conductive material. The probe has an upper region to be disposed above the surface of the liquid, a lower region to be disposed below the surface of the liquid, and a middle region. A heater adds heat to the probe, and temperature sensors may measure the temperature of the probe in the upper and lower regions. Electrical circuitry may be used to control and receive signals from the various components and to measure the electrical resistance between a location in the upper region of the probe and a location in the lower region of the probe. The liquid level may be computed as a function of the measured values, the probe dimensions, and the known temperature dependence of the electrical resistance of the probe.

A device for measuring the level in a reservoir of an inkjet printer, comprising: an electrode, which has a first end and an second end, and which is covered from the first end up to an intermediate level between the first end and the second end, with an electrically insulating coating, where the electrode has capacitive behavior for a level of liquid between the first end and the intermediate level, and resistive behavior beyond this, circuit for measuring a signal which is characteristic of capacitive behavior of the device, for a liquid level between the first end and the intermediate level, and for identifying resistive behavior of the device for a level of the liquid above the intermediate level, circuit for estimating or calculating, from the characteristic signal, a height of the liquid contained in the reservoir, for a liquid level between the first end and the intermediate level.

A liquid level measurement circuit includes: a probe, a reference electrical signal module and a potential conversion module, where the probe extends into a liquid level accommodation body, and the liquid level accommodation body accommodates a measurement liquid module. If the liquid level of said liquid is lower than a preset liquid level, a positive electrode conductor and/or a negative electrode conductor are/is not immersed in the measurement liquid, and an output end of the potential conversion module outputs a first electrical signal; and if the liquid level of the measurement liquid is not lower than the preset liquid level, the positive electrode conductor and the negative electrode conductor are immersed in the measurement liquid, and the output end of the potential conversion module outputs a second electrical signal. The accuracy of liquid level measurement can be improved.

A contacting device is provided for an impedance limit switch, the contacting device including: a printed circuit board having an electrically conductive contact surface; a radially disposed annular spring configured to establish electrical contact between the electrically conductive contact surface of the printed circuit board and at least one electrode of the impedance limit switch; and a non-conductive housing element. An impedance limit switch is also provided, including the contacting device; an electronic cup; and a measuring head configured to carry out a conductive and/or capacitive measurement and to record measurement data, the contacting device being configured to transmit the measurement data from the measuring head to the electronic cup via the contacting unit.