Patent ID: 12247860

DETAILED DESCRIPTION OF THE INVENTION

For purposes of the description hereinafter, the terms “end,” “upper,” “lower,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” “lateral,” “longitudinal,” and derivatives thereof shall relate to the invention as it is oriented in the drawing figures. However, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments or aspects of the invention. Hence, specific dimensions and other physical characteristics related to the embodiments or aspects of the embodiments or aspects disclosed herein are not to be considered as limiting unless otherwise indicated.

No aspect, component, element, structure, act, step, function, instruction, and/or the like used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more” and “at least one.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, etc.) and may be used interchangeably with “one or more” or “at least one.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based at least partially on” unless explicitly stated otherwise.

As used herein, the terms “communication” and “communicate” may refer to the reception, receipt, transmission, transfer, provision, and/or the like of information (e.g., data, signals, messages, instructions, commands, and/or the like). For one unit (e.g., a device, a system, a component of a device or system, combinations thereof, and/or the like) to be in communication with another unit means that the one unit is able to directly or indirectly receive information from and/or transmit information to the other unit. This may refer to a direct or indirect connection that is wired and/or wireless in nature. Additionally, two units may be in communication with each other even though the information transmitted may be modified, processed, relayed, and/or routed between the first and second unit. For example, a first unit may be in communication with a second unit even though the first unit passively receives information and does not actively transmit information to the second unit. As another example, a first unit may be in communication with a second unit if at least one intermediary unit (e.g., a third unit located between the first unit and the second unit) processes information received from the first unit and communicates the processed information to the second unit. In some non-limiting embodiments or aspects, a message may refer to a network packet (e.g., a data packet and/or the like) that includes data. It will be appreciated that numerous other arrangements are possible. It will be appreciated that numerous other arrangements are possible.

As used herein, the term “server” may refer to one or more computing devices, such as processors, storage devices, and/or similar computer components that communicate with client devices and/or other computing devices over a network, such as the Internet or private networks, and, in some examples, facilitate communication among other servers and/or client devices. It will be appreciated that various other arrangements are possible. As used herein, the term “system” may refer to one or more computing devices or combinations of computing devices such as, but not limited to, processors, servers, client devices, software applications, and/or other like components. In addition, reference to “a server” or “a processor,” as used herein, may refer to a previously-recited server and/or processor that is recited as performing a previous step or function, a different server and/or processor, and/or a combination of servers and/or processors. For example, as used in the specification and the claims, a first server and/or a first processor that is recited as performing a first step or function may refer to the same or different server and/or a processor recited as performing a second step or function.

Non-limiting embodiments or aspects of the present invention are directed to systems, devices, products, apparatus, and/or methods for adjusting a fluid flow measurement. In some non-limiting embodiments or aspects, a flow sensor may include a fluid flow path; a first sensor configured to determine a first measurement of at least one of a thermal diffusivity of a fluid in the fluid flow path and a viscosity of the fluid in the fluid flow path; a second sensor configured to determine a second measurement of at least one of a fluid flow velocity of the fluid in the fluid flow path and a volumetric flow rate of the fluid in the fluid flow path; and at least one processor configured to adjust the second measurement based on the first measurement. In some non-limiting embodiments or aspects, a method may include receiving fluid in a fluid flow path of a flow sensor; determining, with a first sensor of the flow sensor, a first measurement of at least one of a thermal diffusivity of the fluid in the fluid flow path and a viscosity of the fluid in the fluid flow path; determining, with a second sensor of the flow sensor, a second measurement of at least one of a fluid flow velocity of the fluid in the fluid flow path and a volumetric flow rate of the fluid in the fluid flow path; and adjusting, with at least one processor, the second measurement based on the first measurement.

In this way, a thermal property measurement and/or a viscosity measurement is used to adjust or correct calorimetric and/or thermal time-of-flight flow velocity measurements, which enables a flow sensor to more accurately determine flow velocity and/or volumetric flow rate of fluids with thermal diffusivities and/or viscosities different than that for which the flow sensor is calibrated. Accordingly, embodiments or aspects of the present invention may enable more accurate real-time measurement of dispensed volume of a fluid (e.g., dispensed volume of a medication fluid to a patient, etc.).

Referring now toFIG.1A,FIG.1Ais a diagram of an example environment100in which devices, systems, and/or methods, described herein, may be implemented. As shown inFIG.1, environment100includes flow sensor102, fluid identification system110, network112, and remote system114. Flow sensor102, fluid identification system110, and remote system114may interconnect (e.g., establish a connection to communicate, etc.) via wired connections, wireless connections, or a combination of wired and wireless connections.

Flow sensor102may include fluid flow path104, first sensor106, and second sensor108. Fluid flow path104may include a wall defining a flow channel for fluid. For example, fluid flow path104may include a cylindrical flow path having a radius R, a flow path with a square cross-section, a flow path with a rectangular cross-section, and/or the like. In some non-limiting embodiments or aspects, first sensor106and/or second sensor108are located within fluid flow path104. For example, first sensor106and/or second sensor108can be connected to an inside surface of the wall defining the flow channel of fluid flow path104(e.g., at an edge of the flow channel, etc.). First sensor106and second sensor108may interconnect (e.g., establish a connection to communicate, etc.) via a wired connection, a wireless connection, or a combination of a wired and a wireless connection.

In some non-limiting embodiments or aspects, second sensor108is spaced apart from first sensor106in a fluid flow direction of fluid flow path104. For example, in an implementation of a non-limiting embodiment or aspect of flow sensor102in which fluid flows from left to right in fluid flow path104as shown inFIG.1A, second sensor108may be located to the right of first sensor106. As an example, fluid in fluid flow path104may flow over or past first sensor106before the fluid in fluid flow path104flows over or past second sensor108.

First sensor106may include one or more devices capable of receiving information from and/or communicating information to second sensor108, fluid identification system110, and/or remote system114via network112. In some non-limiting embodiment or aspects, first sensor106is configured to determine a first measurement of at least one of a thermal diffusivity of a fluid in fluid flow path104and a viscosity of the fluid in fluid flow path104.

In some non-limiting embodiments or aspects, first sensor106includes a thermal diffusivity measurement sensor or chip configured to measure a thermal diffusivity of a fluid in fluid flow path104. For example, in an implementation of a non-limiting embodiment or aspect of flow sensor102as shown inFIG.1B, first sensor106may include a resistive heater (RH) layer extending in a direction parallel to fluid flow path104between a first resistive temperature detector (RTD) layer or thermopile and a second RTD layer or thermopile extending in the direction parallel to fluid flow path104(e.g., a RH layer equally spaced from the first RTD layer and the second RTD layer, etc.). As an example, first sensor106can pulse, modulate, or continuously operate the RH layer and sense or measure a temperature with the RTD layers or thermopiles to determine the first measurement including the thermal diffusivity of a fluid in fluid flow path104(e.g., to provide a signal which is interpreted to determine the thermal diffusivity, etc.). In such an example, first sensor106may be located in a substantially no-flow environment within fluid flow path104due to first sensor106(e.g., the RH layer and first and second RTD layers of first sensor106, etc.) being oriented parallel to the flow of the fluid, which enables a heat pulse from the RH layer to transfer to and/or be detected by the first and second RTD layers or thermophiles before the flow of the fluid in fluid flow path104carries the heat pulse beyond or past the first and second RTD layers or thermopiles of first sensor106.

In some non-limiting embodiments or aspects, first sensor106includes an in situ fluid thermal property measurement apparatus configured to measure a thermal diffusivity of a fluid in fluid flow path104, such as a transient hot wire thermal conductivity measurement sensor, a bridge-based micromachined sensor, a transient hot-strip sensor, and/or the like as described in Hans Roder, “A Transient Hot Wire Thermal Conductivity Apparatus for Fluids”, Journal of Research of the National Bureau of Standards, Vol. 86, No. 5, September-October 1981; S. Gustaffson et al., “Transient hot-strip method for simultaneously measuring thermal conductivity and thermal diffusivity of solids and fluids”, J. Phys. D: Appl. Phys., Vol 12, p 1411 (1979); and R. Beigelbeck et al., “A Novel Measurement Method for the Thermal Properties of Liquids by utilizing a bridge-based micromachined sensor”. Meas. Sci. Technology, Vol. 22, pp 105407 (2011), each of which is hereby incorporated by reference in its entirety.

In some non-limiting embodiments or aspects, first sensor106includes a viscosity measurement sensor or chip configured to measure a viscosity of a fluid in fluid flow path104. For example, first sensor106may include a MEMs viscosity measurement sensor or chip, such as described in A Ballato, “MEMS Fluid Viscosity Sensor”, IEEE Trans Ultras Ferroelectr Freq Control 2010, vol 57, pp 669-76, the entire contents of which is hereby incorporated by reference.

Second sensor108may include one or more devices capable of receiving information from and/or communicating information to first sensor106, fluid identification system110, and/or remote system114via network112. In some non-limiting embodiments or aspects, second sensor108is configured to determine a second measurement of at least one of a fluid flow velocity of the fluid in fluid flow path104and a volumetric flow rate of the fluid in the fluid flow path104. In some non-limiting embodiments or aspects, second sensor108is calibrated to determine the second measurement for a first type of the fluid, and the fluid in fluid flow path104includes a second type of the fluid different than the first type of the fluid. In some non-limiting embodiments or aspects, second sensor108is configured to receive the first measurement from first sensor106and adjust the second measurement based on the first measurement. In some non-limiting embodiments or aspects, first sensor106is configured to receive the second measurement from second sensor108and adjust the second measurement based on the first measurement.

In some non-limiting embodiments or aspects, second sensor108includes a calorimetric or dual-mode calorimetric/thermal time-of-flight sensor or chip. For example, second sensor108may include a MEMS time-of-flight thermal mass flow meter as described in U.S. Pat. No. 8,794,082 to Huang et al., and/or a MEMs device as described in Ellis Meng, “MEMS Technology and Devices for a Micro Fluid Dosing System”, Doctoral Thesis, California Institute of Technology, 2003, the entire contents of each of which is hereby incorporated by reference. As an example, referring again toFIG.1B, second sensor108may include a RH layer extending in a direction perpendicular to fluid flow path104between a first RTD layer or thermopile and a second RTD layer or thermopile extending in the direction perpendicular to fluid flow path104. In such an example, second sensor108can pulse, modulate, or continuously operate the RH layer and sense or measure a temperature variation with the RTD layers or thermopiles to determine the second measurement of at least one of a fluid flow velocity of the fluid in fluid flow path104and a volumetric flow rate of the fluid in the fluid flow path104(e.g., to provide a signal which is interpreted to determine the fluid flow velocity and/or the volumetric flow rate, etc.) according to the calibration of second sensor108.

In some non-limiting embodiments or aspects, as shown inFIG.1B, a spacing between the RH layer and the first RTD layer and the second RTD layer in first sensor106is less than a spacing between the RH layer and the first RTD layer and the second RTD layer in second sensor108. For example, use of calorimetric or dual-mode calorimetric/thermal time-of-flight sensors or chips as described herein for calorimetric mode flow measurement technology functions demonstrates that these calorimetric sensors or chips have a sufficient sensitivity to measure a thermal diffusivity at a substantially zero flow as described herein. As an example, a calorimetric or dual-mode calorimetric/thermal time-of-flight sensor or chip configured or implemented as a thermal diffusivity measurement chip (e.g., as first sensor106) may have a significantly smaller spacing between the RH layer and the RTD layers or thermopiles than a calorimetric or dual-mode calorimetric/thermal time-of-flight sensor or chip configured or implemented as a flow velocity measurement chip (e.g., as second sensor108).

Fluid identification system110may include one or more devices capable of receiving information from and/or communicating information to first sensor106, second sensor108, and/or remote system114via network112. In some non-limiting embodiments or aspects, fluid identification system110includes a fluid identification sensor configured to identify a type of a fluid in fluid flow path104and provide an identification of the type of the fluid in fluid flow path104. In some non-limiting embodiments or aspects, fluid identification system110is incorporated or implemented in flow sensor102. For example, flow sensor102may include a fluid identification sensor configured to identify a type of fluid in fluid flow path104and provide an identification of the type of the fluid in fluid flow path104.

Network112may include one or more wired and/or wireless networks. For example, network112may include a cellular network (e.g., a long-term evolution (LTE) network, a third generation (3G) network, a fourth generation (4G) network, a code division multiple access (CDMA) network, etc.), a public land mobile network (PLMN), a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), a telephone network (e.g., the public switched telephone network (PSTN)), a private network, an ad hoc network, an intranet, the Internet, a fiber optic-based network, a cloud computing network, a short range wireless communication network (e.g., a Bluetooth network, a near field communication (NFC) network, etc.) and/or the like, and/or a combination of these or other types of networks.

Remote system114may include one or more devices capable of receiving information from and/or communicating information to first sensor106, second sensor108, and/or fluid identification system110via network112. In some non-limiting embodiments or aspects, remote system114is in communication with a data storage device, which may be local or remote to remote system114. In some non-limiting embodiments or aspects, remote system114is capable of receiving information from, storing information in, communicating information to, or searching information stored in the data storage device. In some non-limiting embodiments or aspects, remote system114is configured to receive the first measurement from first sensor106and the second measurement from second sensor108and adjust the second measurement based on the first measurement.

The number and arrangement of devices and networks shown inFIG.1Aare provided as an example. There may be additional devices and/or networks, fewer devices and/or networks, different devices and/or networks, or differently arranged devices and/or networks than those shown inFIG.1A. Furthermore, two or more devices shown inFIG.1Amay be implemented within a single device, or a single device shown inFIG.1Amay be implemented as multiple, distributed devices. Additionally, or alternatively, a set of devices (e.g., one or more devices) of environment100may perform one or more functions described as being performed by another set of devices of environment100.

Referring now toFIG.2,FIG.2is a diagram of example components of a device200. Device200may correspond to one or more devices of flow sensor102, one or more devices of first sensor106, one or more devices of second sensor108, one or more devices of fluid identification system110, and/or one or more devices of remote system114. In some non-limiting embodiments or aspects, flow sensor102, first sensor106, second sensor108, fluid identification system110, and/or remote system114can include at least one device200and/or at least one component of device200. As shown inFIG.2, device200may include a bus202, a processor204, memory206, a storage component208, an input component210, an output component212, and a communication interface214.

Bus202may include a component that permits communication among the components of device200. In some non-limiting embodiments or aspects, processor204may be implemented in hardware, firmware, or a combination of hardware and software. For example, processor204may include a processor (e.g., a central processing unit (CPU), a graphics processing unit (GPU), an accelerated processing unit (APU), etc.), a microprocessor, a digital signal processor (DSP), and/or any processing component (e.g., a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), etc.) that can be programmed to perform a function. Memory206may include random access memory (RAM), read only memory (ROM), and/or another type of dynamic or static storage device (e.g., flash memory, magnetic memory, optical memory, etc.) that stores information and/or instructions for use by processor204.

Storage component208may store information and/or software related to the operation and use of device200. For example, storage component208may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, a solid state disk, etc.), a compact disc (CD), a digital versatile disc (DVD), a floppy disk, a cartridge, a magnetic tape, and/or another type of computer-readable medium, along with a corresponding drive.

Input component210may include a component that permits device200to receive information, such as via user input (e.g., a touch screen display, a keyboard, a keypad, a mouse, a button, a switch, a microphone, etc.). Additionally, or alternatively, input component210may include a sensor for sensing information (e.g., a global positioning system (GPS) component, an accelerometer, a gyroscope, an actuator, etc.). Output component212may include a component that provides output information from device200(e.g., a display, a speaker, one or more light-emitting diodes (LEDs), etc.).

Communication interface214may include a transceiver-like component (e.g., a transceiver, a separate receiver and transmitter, etc.) that enables device200to communicate with other devices, such as via a wired connection, a wireless connection, or a combination of wired and wireless connections. Communication interface214may permit device200to receive information from another device and/or provide information to another device. For example, communication interface214may include an Ethernet interface, an optical interface, a coaxial interface, an infrared interface, a radio frequency (RF) interface, a universal serial bus (USB) interface, a Wi-Fi® interface, a cellular network interface, and/or the like.

Device200may perform one or more processes described herein. Device200may perform these processes based on processor204executing software instructions stored by a computer-readable medium, such as memory206and/or storage component208. A computer-readable medium (e.g., a non-transitory computer-readable medium) is defined herein as a non-transitory memory device. A memory device includes memory space located inside of a single physical storage device or memory space spread across multiple physical storage devices.

Software instructions may be read into memory206and/or storage component208from another computer-readable medium or from another device via communication interface214. When executed, software instructions stored in memory206and/or storage component208may cause processor204to perform one or more processes described herein. Additionally, or alternatively, hardwired circuitry may be used in place of or in combination with software instructions to perform one or more processes described herein. Thus, embodiments or aspects described herein are not limited to any specific combination of hardware circuitry and software.

The number and arrangement of components shown inFIG.2are provided as an example. In some non-limiting embodiments or aspects, device200may include additional components, fewer components, different components, or differently arranged components than those shown inFIG.2. Additionally, or alternatively, a set of components (e.g., one or more components) of device200may perform one or more functions described as being performed by another set of components of device200.

Referring now toFIG.3,FIG.3is a flowchart of a non-limiting embodiment or aspect of a process300for adjusting a fluid flow measurement. In some non-limiting embodiments or aspects, one or more of the steps of process300may be performed (e.g., completely, partially, etc.) by flow sensor102(e.g., one or more devices of flow sensor102, such as first sensor106, second sensor108, and/or the like). In some non-limiting embodiments or aspects, one or more of the steps of process300may be performed (e.g., completely, partially, etc.) by another device or a group of devices separate from or including flow sensor102, such as fluid identification system110(e.g., one or more devices of fluid identification system110) and/or remote system114(e.g., one or more devices of remote system114).

As shown inFIG.3, at step302, process300includes receiving fluid in a fluid flow path of a flow sensor. For example, flow sensor102receives fluid in fluid flow path104. As an example, the fluid in the fluid flow path may include a medication fluid, an IV therapy fluid, blood, and/or the like

As further shown inFIG.3, at step304, process300includes determining a first measurement of at least one of a thermal diffusivity of the fluid in the fluid flow path and a viscosity of the fluid in the fluid flow path. For example, first sensor106determines a first measurement of at least one of a thermal diffusivity of the fluid in fluid flow path104and a viscosity of the fluid in fluid flow path104. As an example, first sensor106senses or measures at least one of a thermal diffusivity of the fluid in fluid flow path104and a viscosity of the fluid in fluid flow path104.

In some non-limiting embodiments or aspects, first sensor106measures a thermal diffusivity of the fluid in fluid flow path104, which is a relevant parameter for calibration of a calorimetric or dual-mode calorimetric/thermal time-of-flight sensor or chip. Thermal diffusivity α of a fluid may be defined according to the following Equation (1):
α=k/ρ*Cp(1)
where k=thermal conductivity (e.g., W/m K), ρ=density (e.g., kg/m3), and Cp=specific heat capacity (e.g., J/kg K). For example, a model of an impact of a variation in thermal diffusivity on an accuracy of thermal flow sensors is described in Steven Bindels, “Dependency of the Thermal Fluid Properties on Fluid Flow Sensor”, report on Masters Internship at Philips Research, BMTE 09.46 Eindhoven University of Technology and Philips-Eindhoven. Eindhoven, The Netherlands. November 2009 (hereinafter “Bindels”), the entire contents of which is hereby incorporated by reference.

In some non-limiting embodiments or aspects, first sensor measures a viscosity of the fluid in fluid flow path104, which is a relevant parameter for calibration of a calorimetric or dual-mode calorimetric/thermal time-of-flight sensor or chip. Viscosity of a fluid may be defined as described herein below in more detail with respect toFIG.1C. For example, a model of an impact of a variation in viscosity on an accuracy of thermal flow sensors is described Bindels.

In some non-limiting embodiments or aspects, first sensor106provides the first measurement to second sensor108, fluid identification system110, and/or remote system114, and second sensor108, fluid identification system110, and/or remote system114receives the first measurement from first sensor106.

As further shown inFIG.3, at step306, process300includes determining a second measurement of at least one of a fluid flow velocity of the fluid in the fluid flow path and a volumetric flow rate of the fluid in the fluid flow path. For example, second sensor108determines a second measurement of at least one of a fluid flow velocity of the fluid in fluid flow path104and a volumetric flow rate of the fluid in fluid flow path104. As an example, second sensor108senses or measures at least one of a fluid flow velocity of the fluid in fluid flow path104and a volumetric flow rate of the fluid in fluid flow path104.

In some non-limiting embodiment or aspects, determining the second measurement is based on at least one of a calorimetric mode of second sensor108and a thermal time-of-flight mode of second sensor108. For example, second sensor108measures at least one of a fluid flow velocity of the fluid in fluid flow path104and a volumetric flow rate of the fluid in fluid flow path104in at least one of a calorimetric mode (e.g., using calorimetric measurements and/or properties, etc.) and a thermal time-of-flight mode (e.g., using thermal time-of-flight measurements and/or properties, etc.).

In some non-limiting embodiments or aspects, second sensor108provides the second measurement to first sensor106, fluid identification system110, and/or remote system114, and first sensor106, fluid identification system110, and/or remote system114receives the second measurement from second sensor108.

As further shown inFIG.3, at step308, process300includes adjusting the second measurement based on the first measurement. For example, first sensor106, second sensor108, fluid identification system110, and/or remote system114adjusts the second measurement based on the first measurement. As an example, first sensor106, second sensor108, fluid identification system110, and/or remote system114adjusts the second measurement based on the first measurement in real-time (e.g., during the flow of the fluid in fluid flow path104from which the first measurement and the second measurement are determined, etc.).

In some non-limiting embodiments or aspects, a calibration accuracy of second sensor108(e.g., an accuracy of flow rate measurements by second sensor108, etc.) is impacted to varying degrees by differences in thermal diffusivity and viscosity between the fluid in fluid flow path104(e.g., a fluid under test, etc.) and a particular fluid with which second sensor108is calibrated. As an example, if second sensor108is calibrated for flow measurement with a particular fluid (e.g. water, a first type of medication fluid, etc.) and flow measurement of a different fluid (e.g., a medication fluid, a different type of medication fluid, etc.) is desired or performed, the flow measurement calibration of second sensor108can be adjusted or corrected by using the thermal diffusivity measurement and/or the viscosity measurement of the fluid in fluid flow path104measured by first sensor106to adjust or correct a fluid flow velocity measurement and/or a volumetric flow rate measurement of the fluid in the fluid flow path104measured by second sensor108. In such an example, the second measurement by second sensor108can be adjusted based on a ratio of the at least one of the thermal diffusivity of the fluid in fluid flow path104(e.g., the fluid under test, etc.) and the viscosity of the fluid in fluid flow path104(e.g., the fluid under test, etc.) to at least one of a thermal diffusivity of the particular calibration fluid and a viscosity of the particular calibration fluid.

In some non-limiting embodiments or aspects, a fluid flow velocity of the fluid in fluid flow path104and/or a volumetric flow rate of the fluid in the fluid flow path104measured by second sensor108is adjusted or corrected based on one or more theoretical models of an impact of thermal properties of fluids on flow rate measurements by calorimetric or dual-mode calorimetric/thermal time-of-flight flow sensors as described in C. J. Hepp et al., “Design and Characterization of a Thermal Sensor Achieving Simultaneous Measurement of Thermal Conductivity and Flow Speed”, Transducers 2015, Anchorage, Alaska, USA, Jun. 21-25, 2015; J. E. Hardy et al., “Empirical Correlations for Thermal Flowmeters Covering a Wide Range of Thermal-Physical Properties”, National Conference of Standard Labs 1999 Workshop and Symposium, Charlotte, NC; and M. A. Repko, “Automatic Thermal Conductivity Compensation for Fluid Flow Sensing Using Chemometrics” U.S. Pat. No. 7,127,366. Oct. 24, 2006, each of which is hereby incorporated by reference in its entirety. For example, one or more of these described models of the impact of thermal properties of fluids on flow rate measurements can be applied to implement an adjustment or correction in the second measurement from second sensor108(e.g., an adjustment or correction to a volumetric flow rate measurement received from second sensor108, an adjustment or correction in flow sensor firmware/software of second sensor108used to determine and/or process the second measurement, etc.) based upon a ratio of the thermal diffusivity (and/or thermal conductivity) of the fluid in fluid flow path104(e.g., the fluid under test) to the thermal diffusivity (and/or thermal conductivity) of the particular fluid for which the second sensor108is calibrated. In such an example, an impact of physical properties of a fluid on the flow measurement process of calorimetric and thermal time-of-flight flow sensors, which can be applied to adjust a fluid flow velocity of the fluid in fluid flow path104and/or a volumetric flow rate of the fluid in the fluid flow path104measured by second sensor108, is described in sections 2.1.2 and 2.1.3 of J. T. W. Kuo, Lawrence Yu, Ellis Meng, “Micromachined Thermal Flow Sensors—A Review”, Micromachines, Volume 3, pp. 550-573 (2012) (hereinafter “Kuo”), the entire contents of which is hereby incorporated by reference. In some non-limiting embodiments, an impact of a boundary layer thickness, which is a function of viscosity, for a calorimetric flow sensor, which is described in in section 2.1.2 of Kuo, can be applied to adjust a fluid flow velocity of the fluid in fluid flow path104and/or a volumetric flow rate of the fluid in the fluid flow path104measured by second sensor108.

In some non-limiting embodiment or aspects, a fluid flow velocity of the fluid in fluid flow path104and/or a volumetric flow rate of the fluid in the fluid flow path104measured by second sensor108is adjusted or corrected based on one or more fluid mechanics principles applied to implement an adjustment or correction in the second measurement by second sensor108(e.g., an adjustment or correction to a volumetric flow rate measurement received from second sensor108, an adjustment or correction in flow sensor firmware/software of second sensor108, etc.) based on a viscosity of the fluid in fluid flow path104(e.g., the fluid under test) measured by first sensor106. For example, second sensor108, such as a thermal flow sensor (e.g., a calorimetric and/or thermal time-of-flight flow sensor, etc.) may measure flow velocity at a point relatively far from a center of a flow channel (which may be cylindrical or of square, rectangular or other cross section) and provide a volumetric flow rate via a calibration which is performed for a particular calibration fluid. As an example, in a more simple case of fully developed laminar flow in a cylindrical flow path, as shown inFIG.1Cand discussed in more detail herein below, the laminar flow velocity profile is a parabolic function of radial position from the center of the flow channel or “pipe” (e.g., the cylindrical flow sensor's region of flow sensing, etc.) and the flow velocity at the position of the flow sensor MEMS chip surface, the mean and maximum flow velocity, and the volumetric flow rate are linearly related by the viscosity of the fluid. Thus, when a volumetric flow rate of a fluid other than that for which the sensor is calibrated is desired or measured, the measured viscosity from the MEMS viscosity sensor (e.g., first sensor106, etc.) can be used to linearly adjust the volumetric flow rate measurement by the flow sensor (e.g., second sensor108, etc.) via a viscosity ratio of the fluid being measured and the calibration fluid according to equations defined below with respect toFIG.1C.

Referring now toFIG.1C,FIG.1Cis a diagram of a non-limiting embodiment or aspect of an ideal parabolic laminar flow velocity profile in a fluid flow path of a flow sensor ofFIG.1A. As shown inFIG.1C, an ideal parabolic laminar flow velocity profile may exist in well-developed laminar flow in a pipe or tubing (e.g., in a cylindrical flow path) of radius R. Second sensor108may be configured to measure a flow velocity at a surface of second sensor108at radial position r=Rsensor. Due to a no-slip velocity condition, second sensor108may not be flush with the wall of fluid flow path104. A flow velocity V(Rsensor) measured at second sensor108at radial position r=Rsensorcan be correlated to a maximum flow velocity Vmax=V(0) observed at r=0 and to a volumetric flow rate through the pipe or tubing. A flow velocity profile for fully developed laminar flow in the pipe of radius R can be defined according to the following Equation (2):
V(r)=Vmax[1−(r/R)2]  (2)
where Vmax=2*Vavg, Vavg=an average flow velocity of the laminar flow, Vmax=[(a pressure drop along a length L of the pipe)*R2/4*(viscosity)*(L) and is a centerline velocity of the laminar flow, and a volumetric flow rate Q for the fully developed laminar flow in the pipe of radius R can be defined according to the following Equation (3):
Q=(π)*R2*Vmax/2  (3)

In some non-limiting embodiments or aspects, if second sensor108(e.g., a MEMS thermal flow sensor chip, etc.) is located in an area or zone of fluid flow path104at which laminar flow is not fully developed (e.g., within a entrance length region where a velocity boundary layer exists, etc.) mathematics of the relationship between the measured fluid viscosity, the measured fluid velocity at the surface of the MEMS thermal flow sensor chip, and an adjustment or correction to the volumetric flow rate relative to the volumetric flow rate the flow sensor calculates based upon its calibration with a fluid of a different viscosity than the fluid flowing through fluid flow path104are more complicated than in the ideal laminar flow case described herein with respect toFIG.1C, but the concept of an adjustment or correction mechanism based on a viscosity measurement is similar and not described herein in detail in the interest of brevity.

In some non-limiting embodiments or aspects, a fluid flow velocity of the fluid in fluid flow path104and/or a volumetric flow rate of the fluid in the fluid flow path104measured by second sensor108is adjusted or corrected based a combination of a thermal property measurement by first sensor106and a viscosity measurement by first sensor106. For example, first sensor106may include a thermal property MEMs chip and a viscosity measurement MEMs chip. As an example, a fluid flow velocity of the fluid in fluid flow path104and/or a volumetric flow rate of the fluid in the fluid flow path104measured by second sensor108can be adjusted or corrected based on the thermal diffusivity ratios and the viscosity ratios between the fluid under test and the calibration fluid as described herein and/or one or more models of an impact of physical properties of a fluid on a flow measurement process of calorimetric and/or thermal time-of-flight sensors as described in Kuo.

In some non-limiting embodiments or aspects, adjusting the second measurement includes controlling second sensor108to switch, based on the first measurement, between (i) determining the second measurement based on only the calorimetric mode and (ii) determining the second measurement based on only the thermal time-of-flight mode. In some non-limiting embodiment or aspects, adjusting the second measurement includes controlling second sensor108to switch, based on the first measurement, between (i) determining the second measurement based on only one of the calorimetric mode and the thermal time-of-flight mode and (ii) determining the second measurement based on each of the calorimetric mode and the thermal time-of-flight mode. For example, measured thermal properties of the fluid and/or measured viscosity of the fluid can be used to determine an appropriate point in time to switch from utilization of a calorimetric mode to utilization of a thermal time-of-flight mode for a dual mode sensor if only one of these modes is used to determine a flow rate measurement at a time, or to combine information from these two modes in a fashion which calculates a more accurate flow velocity and volumetric flow rate passing through flow sensor102. The determination of the switch point and/or volumetric flow rate adjustment or correction can be based upon empirical data/measurements of impact of differences between the thermal diffusivity (and/or thermal conductivity) of the fluid under test relative to the thermal diffusivity (and/or thermal conductivity) of the flow sensor calibration fluid and/or viscosity of the fluid under test relative to the viscosity of the flow sensor calibration fluid on volumetric flow rate measurement (of either a calorimetric only mode flow sensor or a dual mode calorimetric/thermal time-of-flight thermal flow sensor), and an optimal switch point between the calorimetric and thermal-time-of-flight modes for a dual mode thermal flow sensor.

In some non-limiting embodiments or aspects, flow sensor102and/or remote system114provides adjusted data as output via output component212, (e.g., via a display of the adjusted second measurement, etc.), wherein the adjusted data is based on the adjusted second measurement. In some non-limiting embodiments or aspects, first sensor106, second sensor108, fluid identification system110, and/or remote system114controls delivery of the fluid to and/or from flow sensor102(and/or to and/or from another fluid delivery device through which the fluid flows, to and/or from a patient, etc.) based on the adjusted second measurement. For example, first sensor106, second sensor108, fluid identification system110, and/or remote system114controls one or more valves and/or one or more fluid delivery pumps to modify the flow of the fluid in fluid flow path104based on the adjusted second measurement.

Further details regarding step308of process300are provided below with regard toFIG.4.

Referring now toFIG.4,FIG.4is a flowchart of a non-limiting embodiment or aspect of a process400for adjusting a fluid flow measurement. In some non-limiting embodiments or aspects, one or more of the steps of process400may be performed (e.g., completely, partially, etc.) by flow sensor102(e.g., one or more devices of flow sensor102, such as first sensor106, second sensor108, and/or the like). In some non-limiting embodiments or aspects, one or more of the steps of process400may be performed (e.g., completely, partially, etc.) by another device or a group of devices separate from or including flow sensor102, such as fluid identification system110(e.g., one or more devices of fluid identification system110) and/or remote system114(e.g., one or more devices of remote system114).

As shown inFIG.4, at step402, process400includes receiving an identification of a type of the fluid to be received in the fluid flow path. For example, first sensor106, second sensor108, fluid identification system110, and/or remote system114receives an identification of a type of fluid to be received in fluid flow path104. In some non-limiting embodiments or aspects, the identification is associated with an adjustment factor. For example, an adjustment factor may include a predetermined adjustment or correction to be applied to a fluid flow velocity of the fluid in fluid flow path104and/or a volumetric flow rate of the fluid in the fluid flow path104measured by second sensor108for the type of the identified fluid. As an example, the adjustment factor may be based on previous empirically based or theoretical calculation/modeling based determinations for measurement of the identified type of fluid in flow sensor102.

In some non-limiting embodiments or aspects, fluid identification system110identifies the type of fluid to be received and/or currently in fluid flow path104and provides the identification of the type of fluid to first sensor106, second sensor108, and/or remote system114.

As further shown inFIG.4, at step404, process400includes determining, based on the first measurement, a change in the type of the fluid in the fluid flow path. For example, first sensor106, second sensor108, fluid identification system110, and/or remote system114determines, based on the first measurement, a change in the type of fluid in fluid flow path104. As an example, flow sensor102can be used in a dynamic manner with multiple different types of fluid passing through flow sensor102and a thermal diffusivity measurement and/or a viscosity measurement by first sensor106(e.g., a change in the thermal diffusivity measurement and/or the viscosity measurement that satisfies one or more thresholds, etc.) can be used to determine that a different or new fluid is entering fluid flow path104(e.g., a flow sensing area or region of fluid flow path104including second sensor108, etc.). In such an example, the identification associated with the adjustment factor for the different or new fluid can be used to alert flow sensor102that a change in the type of the fluid in the fluid flow path is about to occur, and the measured thermal diffusivity change (and/or thermal conductivity change) and/or the measured viscosity change from first sensor106can be used by flow sensor102to identify the particular point in time at which the fluid front of the different or new fluid has entered fluid flow path104(e.g., the flow sensing area or region, etc.).

As further shown inFIG.4, at step406, process400includes, in response to determining the change in the type of the fluid in the fluid flow path, adjusting the second measurement based on the adjustment factor. For example, first sensor106, second sensor108, fluid identification system110, and/or remote system114, in response to determining the change in the type of the fluid in fluid flow path104, adjusts the second measurement based on the adjustment factor. As an example, in response to the measured thermal diffusivity change (and/or thermal conductivity change) and/or the measured viscosity change from first sensor106, second sensor108can apply an appropriate empirical and/or theoretical volumetric flow rate measurement adjustment or correction for the new or different fluid that has entered fluid flow path104based on the adjustment factor associated with the new or different fluid. In such an example, second sensor108(e.g., a dual-mode calorimetric/thermal time-of-flight flow sensor, etc.) may have different optimal switch points between calorimetric and thermal time-of-flight operation modes for fluids of different thermal diffusivities and/or different viscosities to maximize or optimize volumetric flow rate measurement performance (e.g., an accuracy of flow measurements, a response time of flow measurements, etc.) As an example, the thermal diffusivity measurement and/or the viscosity measurement can be combined with the adjustment factor to determine a calorimetric/time-of-flight mode switch point for second sensor108for the new or different fluid from previous empirically based or theoretical calculation/modeling based determinations of what that thermal optimum flow sensor measurement mode switch point would be for that particular fluid (e.g., if exact fluid identity is known) or for a fluid of that particular thermal diffusivity (and/or thermal conductivity) and/or viscosity.

Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments or aspects, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments or aspects, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment or aspect can be combined with one or more features of any other embodiment or aspect.