US 5,135,485 A · Capacitance-type fluid level sensor for i.v. and catheter bags

Abstract

A capacitance-type fluid level sensing system, method, and device is disclosed for determining the amount of fluid in a container, for example, a disposable plastic bag used for intravenous (i.v.) injection or collection of waste from a human body (catheter). In one illustrated embodiment, conductive plates are disposed on the outside of the plastic bag and connected to a circuit for detecting any change in the capacitance of the capacitor formed thereby. In another embodiment, the conductive plates are integrally constructed as part of a surface of the electronic device housing, such that the fluid level can be detected when the housing is affixed directly to the outside of the bag. Alternative annunciation, detection, flow rate calculation, display, and housing features are shown in various embodiments.

Claims43

Dependent claims

A fluid level sensing system having capacitance sensing means for determining whether a particular fluid level has been reached in a container used for introducing or removing fluids to or from the human body, said system comprising:

a substantially enclosed container having means for introducing or removing fluids to or from the human body, said container further having nonconductive sidewalls and at least one port for increasing or decreasing the level of fluid in said container;
a capacitor formed of at least two conductive members positioned at a particular location adjacent the external surface of said container such that said members cannot directly contact fluid in said container and such that the capacitance of said capacitor changes as the level of fluid in the container varies above or below said particular location;
means for detecting changes in the value of said capacitor resulting from changes in the level of fluid, and for generating a capacitance signal in response thereto;
means for providing a reference signal indicative of a capacitance value corresponding to a particular fluid level;
means for comparing said capacitance signal with said reference signal, and for generating an output signal in response to the difference between said capacitance signal and said reference signal;
and
means for providing an indication in response to said output signal that said particular fluid level in said container has been reached.

4 more elements

An electronic device for sensing fluid levels in an intravenous injection or catheter administering apparatus, said apparatus constructed of nonconductive material, said electronic device comprising:

means for housing electronic circuitry, said housing means including conductive plates constructed as an integral part of at least one surface of said housing, said housing adapted for positioning said conductive plates on an outside surface of said apparatus to form a capacitor such that the capacitance of said capacitor changes as the level of fluid varies in the apparatus;
means for detecting changes in the value of said capacitor resulting from changes in the level of said fluid, and generating a capacitance signal in response thereto;
and
means for providing an indication in response to said capacitance signal that said particular fluid level in said container has been reached.

1 more element

Dependencies are inferred from the claim text.

Capacitance-type fluid level sensor for i.v. and catheter bags

Life of this patent

Capacitance-type fluid level sensor for i.v. and catheter bags

Life of this patent

Abstract

Claims43