In one example in accordance with the present disclosure a liquid level sensor is described. The sensor includes a carrier and a liquid level sensing interface disposed on the carrier. The liquid level sensing interface includes a number of liquid level sensing devices disposed on an elongated strip. The number of liquid level sensing devices detect a liquid level in a liquid container. The liquid level sensing interface also includes a number of thermal isolation components formed on the elongated strip to thermally isolate adjacent liquid level sensing devices.

A pump assembly with at least one liquid space (32) in an interior. The liquid space (32) contains a liquid or is configured for receiving a liquid. A sensor (34, 42) is arranged in the liquid space (32), which sensor is configured to detect at least one material property of the liquid located in the liquid space (32). A filter element (44) is arranged in the interior of the liquid space (32) such that the filter element (44) shields the sensor (34, 42) with respect to the surrounding liquid space (32), the filter element (44) being permeable to the liquid. A method for controlling a pump assembly is also provided.

A liquid level detector includes: a vertically-mounted accumulator that stores refrigerant; a heater that heats the accumulator; a temperature detector that detects a surface temperature of the accumulator; a pressure detector that detects a pressure of the refrigerant in the accumulator; and a controller. The controller detects a position of a liquid surface of the refrigerant in the accumulator based on a surface temperature of the accumulator detected by the temperature detector when the accumulator is heated by the heater, and a pressure of the refrigerant in the accumulator detected by the pressure detector.

An example printing cartridge includes a fluid container, a sensing die including a plurality of sensing locations in thermal contact with the fluid container, and a voltage comparator to output time-based information by comparing a sensed voltage generated at a selected sensing location of the plurality of sensing locations to a threshold voltage, the time-based information representative of whether a fluid is present at the sensing location.

A liquid level meter includes a first resistive temperature detector; a first temperature measuring body a liquid level detection section a temperature detection section detecting the temperatures of the first resistive temperature detector and the first temperature measuring body; a current control section determining a value of a current to apply to the first resistive temperature detector such that a difference between the temperatures of the first resistive temperature detector and the first temperature measuring body detected by the temperature detection section to be a first constant value; and a power supply unit supplying a current of the determined current value to the first resistive temperature detector; wherein the liquid level detection section determines whether the first resistive temperature detector is present in a liquid or outside of the liquid using the value of the current applied to the first resistive temperature detector.

A fluid level sensing device includes a substrate (210) and a sensing die (216) cantilevered at one end from the substrate. A number of sensing components (218), preferably thermal or impedance sensing components, are disposed on the sensing die and detect a fluid level in a fluid reservoir. A protective member (208) is also cantilevered at one end from the substrate alongside the sensing die. Electrical interconnects (212) output data collected from the number of sensing components. A number of sensing dies may be provided to lengthen the sensing device, in which case the protective cover extends alongside and parallel to the number of sensing dies.

A method of detecting a level of printable fluid in a container includes, with at least one sensing location on a die in thermal contact with the printable fluid in the container, sensing a voltage of a capacitor over time as current from the capacitor leaks through a field effect transistor (FET). The FET and capacitor are associated with the sensing location. The method may further include, based on the voltage of the capacitor over time and a threshold voltage, determining whether the printable fluid is present at the at least one sensing location.

In one example in accordance with the present disclosure a fluid property sensing device is described. The fluid property sensing device includes a substrate having a trench formed therein. The trench includes a bottom surface and opposite side surfaces. A first electrode is disposed on a first side surface of the trench and a second electrode is disposed on a second side surface of the trench. The first electrode and second electrode form a capacitor to measure a complex impedance of a fluid that fills a space between the first electrode and the second electrode. This complex impedance indicates a property of the fluid. A fluid level sensing die, having a number of fluid level sensing components disposed thereon, may be attached to the substrate, preferably in such a way that the fluid level sensing die is surrounded by the trench. In this way the surface area of the electrodes provided in the trench can be increased. The number of level sensing components may be thermal sensing components.

In one example in accordance with the present disclosure a liquid level sensing device is described. The device includes a carrier and a liquid level sensing device disposed on the carrier. The liquid level sensing interface has an aspect ratio of at least 1:50. A number of liquid level sensing components are disposed on the liquid level sensing interface. The number of liquid level sensing components detect a liquid level in a liquid container. The liquid level sensing device also includes an electrical interconnect to output data collected from the number of liquid level sensing components.

Dual level sensing, vacuum monitoring, smart supply cylinders, smart oxygen monitors, and real time data collection functionality are integrated with a cryogenic storage system to improve sample safety and user safety. The dual level sensing system includes two liquid nitrogen level sensors installed into a cryogenic freezer that send redundant level information to a controller. Vacuum monitoring is performed via a gauge, installed on a vacuum port, that communicates data to the controller. The controller further receives level information from supply cylinders and oxygen levels from one or more oxygen monitors. The aforementioned data sources can be integrated into control decisions executed by the controller. In addition, all operational data of the cryogenic storage system is communicated to a cloud-based platform to provide real-time status monitoring, trend analysis, and alarm notifications.