# US 5,701,646 A · Method of making a sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,701,646 A - Document ID: US5701646A - Status: Granted - Kind: A - Application number: 08/564,793 - Filed: 1995-11-29 - Granted: 1997-12-30 - Earliest claimed: 1990-02-02 - Assignees: Isco, Inc. - Inventors: Frederick Alan Nabity; Paul George Wright; Raymond Hulinsky; Douglas Timothy Carson - Web page: https://patentgrep.com/patent/US5701646A ## CPC - F04B 43/12: having peristaltic action - G01F 1/72: Devices for measuring pulsing fluid flows - G01F 3/00: Measuring the volume flow of fluids or fluent solid material wherein the fluid passes through the meter in successive and more or less isolated quantities, the meter being driven by the flow (measuring a proportion of the volume flow G01F5/00) - G01F 3/20: having flexible movable walls, e.g. diaphragms, bellows - G01L 9/0001: {Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means (G01L9/0026, G01L9/0033, G01L9/0082, G01L9/0089, G01L9/0091 take precedence)} - G01N 1/14: Suction devices, e.g. pumps; Ejector devices - F04B 2205/06: Pressure in a (hydraulic) circuit - G01N 2035/0491: {Position sensing, encoding; closed-loop control} - Y10S 310/80: Piezoelectric polymers, e.g. PVDF - Y10T 29/42: Piezoelectric device making - F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F) - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A method of making a sensor wherein flexible conduit means is assembled with a fixture having a strain-sensitive film and electrical connections are made to the film whereby variations in fluid pressure in the conduit means can be detected. ## Claims ### Claim 1 A method of making a sensor for detecting a liquid in a flexible conduit comprising the steps of: providing a flexible conduit means; forming a loop of the flexible conduit means said loop having two legs, and positioning said loop in cooperation with a peristaltic pump; mounting said legs in a fixture wherein a strain-sensitive film in the fixture is positioned adjacent and in contact with one of said legs to sense pressure within the flexible conduit means; and providing electrical connections to the strain-sensitive film adapted to sense periodic strains whereby pulses of pressure transmitted through the flexible conduit means may be detected. ### Claim 2 (depends on 1) A method of making a sensor according to claim 1 in which the step of mounting a flexible conduit means includes the step of mounting a flexible tube and a strain-sensitive film in the fixture wherein the strain-sensitive film and the flexible tube are supported at a location adjacent to a conduit support means whereby at least a portion of the strain-sensitive film is in contact with the conduit when the fixture and conduit are assembled. ### Claim 3 (depends on 2) A method of making a sensor according to claim 2 including the step of permitting: sufficient expansion of the conduit to create strain of an amplitude to permit discrimination of signal from noise wherein said strain-sensitive film is partly stretched in the fixture whereby liquid pumped through the conduit may be detected. ### Claim 4 (depends on 1) A method of making a sensor according to claim 1 including the step of permitting sufficient expansion of the conduit in an opening having a depth of at least the thickness of the conduit plus one-thousandth of an inch. ### Claim 5 (depends on 1) A method of making a sensor according to claim 1 wherein said strain-sensitive film is pre-stretched by the conduit during installation of the conduit into a means for receiving said conduit. ### Claim 6 (depends on 1) A method of making a sensor according to claim 1 wherein after installation said strain-sensitive film has contact with the conduit of at least one-sixteenth of a square inch. ### Claim 7 (depends on 1) A method of making a sensor according to claim 1 including the step of mounting the fixture and a pump at a distance from each other sufficiently close to detect the difference in amplitude of strain when liquid reaches a predetermined point from amplitude before it reaches the predetermined point. ### Claim 8 (depends on 1) A method of making a sensor according to claim 1 in which the strain sensitive film is mounted at a distance no greater than 18 inches from a pump. ### Claim 9 (depends on 1) A method of making a sensor according to claim 1 in which the strain-sensitive film is mounted on the inlet side of a pump. ### Claim 10 (depends on 1) A method of making a sensor according to claim 1 in which the electrical connections to the strain-sensitive film are connected to a programmable computer. ### Claim 11 (depends on 1) A method of making a sensor according to claim 1 including the step of connecting the strain-sensitive film to a programmable computer means for predicting the number of force pulses transmitted through the flexible conduit means to the sensor before sensing the liquid; said programmable computer means having a statistical database. ### Claim 12 (depends on 1) A method of making a sensor according to claim 1 wherein a programmable computer means is programmed to determine which pulses are sensed; said programmable computer means being programmed to count slugs of liquid only when followed by a flow of liquid. ### Claim 13 (depends on 1) A method of making a sensor according to claim 1 including the step of determining when a predetermined volume of liquid has been pumped to a container; counting pulses applied to said electrical connections, and reading from a look-up table the volume of liquid deposited corresponding to said counted pulses.