Patent Publication Number: US-2022236087-A1

Title: Sensor Unit

Description:
1. INTRODUCTION 
     Disclosed herein is a sensor unit that is positioned at a location in a conduit for measuring a property of a fluid flowing through the conduit. 
     2. BACKGROUND 
     Sensors of various types are used to monitor the properties of fluids flowing through conduits. One of the problems associated with obtaining consistent accurate results is that the properties of the flowing fluid and measurements thereof frequently depend on many factors that are not always easy to reliably reproduce, such as the distance of the sensor from the walls of the conduit, the depth to which the sensor is immersed in the fluid, and characteristics of the walls of the conduit. 
     It is therefore a purpose of the present invention to provide an apparatus that enables accurate reproducible determinations of properties of fluids flowing through a conduit. 
     Further purposes and advantages of this invention will appear as the description proceeds. 
     3. SUMMARY 
     Provided herein is a sensor unit that is configured to be positioned at a location in a conduit at which it is desired to measure a property of a fluid flowing through the conduit. In certain embodiments, the sensor unit comprises: a) a sensor support; b) a body section including proximal and distal sides and a center having a chamber, the chamber having a lower part and a top part, the lower part providing an open path between the proximal and distal sides of the body section, thereby providing a flow channel through the body section; c) a socket in the top part of the chamber, the socket configured to receive the sensor support; d) a gasket located on top of the sensor support; e) a clamp configured to press down on the gasket, thereby holding the gasket and sensor support in place in the socket; and f) at least one sensor configured to measure a property of the fluid. The sensor support supports the at least one sensor such that the at least one sensor is maintained in position relative to the walls of the flow channel through the sensor unit and at a constant depth relative to the fluid flowing through the sensor unit. 
     In certain embodiments, the socket comprises shelves on two sides of the chamber that are parallel to side walls on which the sensor support is positioned to form a complete ceiling to the flow channel. 
     In certain embodiments, the sensor unit of any one of the preceding claims, wherein the body section includes at least one of: a) a sensor unit cover; b) an electric cable connected at a first end to an electric circuit on the sensor support and connected at a second end to a control unit; c) short pieces of tube that project through and out of a proximal wall and a distal wall of the body section respectively; d) a cable guide configured to hold in place an electric cable located at the distal side of the body section; e) at least one sensor located on the sensor support; f) electronic circuitry on the sensor support; g) a proximal connector section configured to be attached at its distal end to a tube that projects through and out of the proximal wall of the body section and at its proximal end to the conduit; and h) a distal connector section configured to be attached at its proximal end to a tube that projects through and out of the distal wall of the body section and at its distal end to the conduit. 
     In certain embodiments, the at least one sensor is one of: a temperature sensor, a temperature sensor enabled to provide heat, a pH sensor, a pressure sensor, a flow rate sensor, a sensor for detecting a concentration of at least one substance in the fluid, and a sensor to detect the at least one liquid or gas. 
     In certain embodiments, the sensor support has one of a two dimensional shape and a three dimensional shape. In certain implementations, the sensor support is one of a PCB, a metal plate, a plastic plate, and a ceramic plate. 
     In certain embodiments, the sensor unit further comprises a check valve downstream of the body section. 
     In certain embodiment, the gasket is located between the sensor support and the clamp. 
     In certain embodiments, the clamp comprises an opening through which the electric cable can pass, a cable guide, and two snap-fit legs, wherein each of the snap-fit legs has free end having a latch structure, the snap-fit legs configured to allow the latch structure to snap in place under a ledge at an exterior side wall of the chamber. 
     In certain embodiments, the body section includes a distal connector section having a distal end and the conduit attached to the distal end of the distal connector section is a double-lumen conduit, wherein fluid flows through one of the lumens and an electric cable passes through the second of the lumens. 
     In certain embodiments, the sensor further comprises an electric circuit, an electric cable having conductors, and a plug positioned at an end of the electric cable that connects the electric circuit in the sensor unit to a control unit, wherein the plug comprises a small printed circuit board (PCB) having an electronic circuit, conducting pads on the PCB to which the conductors in the electric cable are electrically connected, the electronic circuit including metal traces that electrically connect electronic components on the PCB to the conducting pads and to pins that are positioned and dimensioned to match channels in a modular connector, the electronic components having at least one of a passive memory component, active components for operating the at least one sensor, accumulating data, performing operations on the accumulated data, and communicating with other systems. 
     Also provided herein is a plug positioned at the end of an electric cable that conducts electricity from a first electrical device to a second electrical device, the plug configured to electrically connect the cable to the second electrical device, wherein the plug comprises: a small printed circuit board (PCB) having electronic components including at least one of i) a passive memory component, and ii) active components that operate sensors, accumulate data, perform operations on the accumulated data, and communicate with the second device and/or other systems; conducting pads positioned on the PCB to which conductors in the electric cable are electrically connected; pins that are positioned and dimensioned to match channels in a modular connector; and an electronic circuit positioned on the PCB, the circuit including metal traces that electrically connect the electronic components on the PCB to the conducting pads and to the pins. 
     All the above and other characteristics and advantages of the invention will be further understood through the following illustrative and non-limitative description of embodiments thereof, with reference to the appended drawings. 
     4.1 DEFINITIONS 
     In this disclosure of the invention, the terms “proximal” and “distal” are used in the common sense, i.e., “proximal” means “closer to the origin or source of flow of a fluid” and “distal” means “further away from the origin or source of flow”. The “proximal direction”, therefore, is “upstream” and the distal direction” is downstream. 
    
    
     
       4.2 BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of a sensor unit as disclosed herein; 
         FIG. 2  is an exploded view showing the internal components of the sensor unit of  FIG. 1 ; 
         FIG. 3  is a perspective view of the body section of the sensor unit of  FIG. 1 ; 
         FIG. 4  is a transverse cross-sectional view of the body section of  FIG. 3 ; 
         FIG. 5  is a side view of the PCB of the sensor unit of  FIG. 1 ; 
         FIG. 6A  and  FIG. 6B  are respectively upper and lower perspective views of the Printed Circuit Board (PCB) of  FIG. 5  with cable attached; 
         FIG. 7  is a transverse cross-sectional view of the body section of  FIG. 3  with the PCB of  FIG. 5  in place; 
         FIG. 8  is a perspective view of the snap-fit clamp element of the sensor unit of  FIG. 1 ; 
         FIG. 9  is a transverse cross-sectional view of the body section of  FIG. 3  with the PCB of  FIG. 5 , a gasket, and the clamp of  FIG. 8  in place; 
         FIG. 10  shows a prior art proximal connector section that can be used to connect the proximal end of the sensor unit of  FIG. 1  to a conduit; 
         FIG. 11  shows a distal auxiliary connector section that can be used to connect the distal end of the sensor unit of  FIG. 1  to a conduit; 
         FIG. 12  shows an example cover of the sensor unit of  FIG. 1 ; and 
         FIG. 13  shows a PCB which is a component of a plug that connects the cable of the sensor unit of  FIG. 1  to a remote device. 
     
    
    
     4. DETAILED DESCRIPTION 
     Disclosed herein is a sensor unit that is configured to be positioned at a location in a conduit at which it is desired to measure some property of a fluid flowing through the conduit, e.g. flow velocity, color, density, viscosity, pH, concentration of gases, chemicals, or other substances such as CO 2  and NO 2  whether in a gaseous state or dissolved in a liquid, etc. The sensor unit comprises a section, called herein the body section, comprising a chamber in which the measurements are carried out, and a support structure that supports the sensor in such a way that it is always located at a given distance from the walls of the flow channel through the sensor and at the same depth relative to the fluid flowing through the sensor unit. The design of the support structure is such that the sensor&#39;s position relative thereto is reliably and repeatably reproducible at the time of manufacturing or assembly, as will be explained below. The interior of the body section is designed to minimize the turbulence of fluids flowing through it. 
     In order to illustrate the invention, the description and figures herein relate to an embodiment comprising a sensor unit that further comprises electronic components used to produce and sense changes in a fluid flowing in the conduit. The sensor can be any type of sensor, electronic, optical, mechanical, ultrasonic, etc. as is currently, or may in the future be, known in the art that would be mounted mutatis mutandis in the same manner as are the electronic components described herein. Many other embodiments are possible, each appropriate to its application, without deviating from the spirit of the invention described herein with reference to this embodiment. 
       FIG. 1  is a perspective view and  FIG. 2  is an exploded view of a sensor unit  100 . Seen in these figures are the following components, which will be described in greater detail herein below: body section  130  comprising proximal end  152  and distal end  154 , cover  132 , Printed Circuit Board (PCB)  140 , electric cable  142 , gasket  144 , and snap-fit clamp element  146  (hereinafter referred to as the “clamp”). In these and the following figures arrow  150  shows the direction of fluid flow through the sensor unit. 
       FIG. 3  is a perspective view of body section  130  of sensor unit  100  and  FIG. 4  is a transverse cross-sectional view of body section  130  looking in the proximal (i.e., upstream) direction. Proximal end  152  and distal end  154  are short pieces of tube that project out of proximal wall  152   a  and distal wall  154   a  of body section  130 , respectively. Proximal end  152  and distal end  154  are shaped and sized to mate respectively with a proximal connector section  126  (shown in  FIG. 10 ) and distal auxiliary connector section  148  of sensor unit  100  (shown in  FIG. 11 ), both of which will be described herein below. In some embodiments, either or both ends may connect directly to a conduit without a connector section. In some embodiments, the body section may be an integral part of a conduit. Different embodiments may have different shapes or sizes of the ends  152  and  154  depending on the object to which each mates. At the distal side of the body section  130  is formed a cable guide  158  that is shaped to hold in place a cable  142  that is electrically connected to a PCB  140 . 
     It should be noted that the body section of the sensor unit may be oriented in any direction, rotating around any of the three axes. For purposes of simplicity, reference is made to the “top”, “bottom”, “sides”, “roof”, “ceiling”, “wall”, etc. of the body section or components thereof, it being understood that this is for convenience only and with respect to the frame of reference illustrated in the figures. With rotation, the “top” may become the “side” or “bottom”, or may be at any angle of rotation around any axis, without deviating from the intent of the disclosure. 
     In the center of body section  130  is formed a socket  160  comprising side walls  164  into which a sensor support, which in this embodiment is a PCB  140 , can be seated securely. The bottom of socket  160  over flow channel  156  is open to allow contact of the fluid flowing through flow channel  156  with sensors on the bottom of the sensor support. On the two sides of the opening are formed shelves  162  on which the sensor support (PCB  140 ) can be positioned to form the top of the flow channel. To prevent turbulence there are no shelves on the proximal and distal ends of the opening. The sides of the sensor support abut side walls  164  surrounding the opening so that the bottom of the sensor support will form a complete ceiling to the channel throughout the length of socket  160 . 
       FIG. 5  is a side view of PCB  140 .  FIG. 6A  and  FIG. 6B  are respectively upper and lower perspective views of PCB  140  with cable  142  attached. As shown, element  168  represents components of an electronic circuit on the PCB on the outer side of the PCB, and an element  170  represents components of an electronic circuit on the PCB on the inner side. Also shown are PCB connector  166  on the PCB  140  and cable plug  172  on cable  142 . In various embodiments, components of the sensing circuit may be on either or both sides of the sensor support. 
     It is noted that in different embodiments of the sensor unit the PCB may comprise different types of sensor elements  170  for example: a thermistor in contact with the liquid that can be used to measure temperature (and/or provide heat); a pH sensor; a pressure sensor; one of various types of flow rate sensors; sensors to detect and/or measure the concentration of different chemicals or substances in the fluid; and sensors to detect the presence and/or concentration or types of different liquids or gases. Any one or more of these sensors of any sensor types can be added to the circuit on the PCB to measure properties of the fluid. 
     In other embodiments of the sensor unit, depending on the properties of the fluid that are to be measured and the type of sensor, the PCB may be replaced with a sensor-support substrate of any material e.g., metal, ceramic, or plastic plate. In some embodiments, the sensor support may not have a flat rectangular shape as described herein, but may have other two or three dimensional shapes. For example, the sensor support may form an arched ceiling to the flow chamber. The sensors need not to be attached adjacent to the surface of the sensor support as shown in the figures herein but can be attached to probes that project orthogonally (or at any angle) from the bottom of the sensor support into the fluid. In embodiments of the sensor unit several sensors may be attached to the probe to measure the same or different properties of the fluid at different distances from the sensor support. In some embodiments, a sensor may comprise components on the inside or outside of the PCB, or both. One or more sensors may also be positioned to lie flush with the surface of the sensor support or even recessed within it. 
     In some embodiments, the sensing circuit may comprise communication means, either wired or wireless. In some embodiments, data may be stored within the sensor unit, e.g., for later retrieval. 
       FIG. 7  is a transverse cross-sectional view of body section  130  viewed from the proximal direction, similar to  FIG. 4 , with the PCB  140  in place on shelves  162  creating a U-shaped portion of flow channel  156  in which the measurements are made. From this figure it can be seen that placing the bottom of PCB  140  in direct contact with the shelves  162 , and using the bottom of the PCB as the top of the flow channel, ensures that the internal sensor component  170  is inserted the exact same depth into the fluid, providing consistent and accurate measurements. In some implementations, this may require the U-shaped portion of flow channel  156  to be full of the flowing liquid, or gas at a certain pressure when measurements are made. This can be accomplished, for example, by use of a check valve in a fluid tube downstream of body section  130 . The U-shaped sides and flat top of the portion of the flow channel at which the measurements are made provide maximum contact of the sensors with a flowing fluid without creating eddies and other disturbances to the flow. 
     Gasket  144  (see  FIG. 9 ) is placed on top of PCB  140  instead of the conventional practice in which a gasket is placed between PCB  140  and the shelves  162 . The gasket is placed on top of the PCB to allow reproducible insertion of the element  170  in the liquid that could not be accomplished if the gasket were under the PCB (i.e., between the PCB  140  and the shelves  162 ). If the gasket were in the conventional arrangement between the PCB and the shelves the variable compressibility of the gasket would influence the position of the sensors relative to the conduit. By placing the sensor support directly upon the shelves, this variability is avoided. The shelves thus form a reference plane, relative to which the sensor position may be accurately and reproducibly set. 
     Selection of suitable materials for the gasket is helpful for optimal sealing characteristics. When the clamp  146  is applied, as will be discussed with respect to  FIG. 9 , a balance can be achieved between the amount of pressure applied (not too high) and the amount of deformation achieved (i.e., enough to keep the elastomer in contact with the surface, but not so much as to lose its compliance). It is helpful to minimize the force for achieving a consistent deformation that can hold over time, temperature, and, for example, for medical applications, ETO (Ethylene Oxide), radiation or other methods of sterilization. In certain embodiments, silicon rubber gaskets with a suitable durometer value and appropriate compression characteristics (achieving compression without undue force) can be used. Also the thickness of the gasket was chosen so that when the clamp  146  is attached to body section  130  the gasket prevents leakage by being slightly compressed without requiring too much force. 
     In certain embodiments, a layer of adhesive can be added to the side of gasket  144  that creates the sealing surface. The adhesive layer can hold the gasket in place on the PCB for the assembly process and also fill in any imperfections of the sealing surfaces. Together these aspects secure a leak-free seal between the PCB  140 , side walls  164  of the recess  160  and the clamp  146 . 
       FIG. 8  is a perspective view of an embodiment of a clamp  146 . Clamp  146  comprises a top  173  having an opening  178  through which the cable  142  can pass to connect to the PCB, a cable guide  180 , and two snap-fit legs  174  which extend perpendicularly from the top  173  of the clamp. Each of the snap-fit legs  174  has a latch structure  176  on its free end configured to enable snapping the clamp  146  into position and holding it securely. The latch structures  176  can be wedge-shaped elements as shown or can have other shapes. 
       FIG. 9  is a transverse cross-sectional view of body section  130  viewed from the proximal direction, similar to  FIG. 7  with gasket  144  and clamp  146  in place. As shown in this figure, the snap-fit legs  174  are made to deform to pass over side walls  160   a  during the assembly process and snap in place when they reach a ledge under side walls  160   a  where the latch structures  176  engage. When latch structures  176  engage, the clamp  146  presses down firmly on gasket  144 , which slightly compresses against PCB  140 , sealing the top of U-shaped flow channel  156 . In the depicted embodiment, the latch structures  176  have a back bevel, e.g. five degrees, to help keep the snap-fit legs from moving off the clamping surface over time or during use. 
     In certain embodiments, the clamp member  146  has sufficient rigidity to maintain compression on the gasket over time, and through various temperature changes and chemical exposure. In certain embodiments, the clamp is designed to remain within plastic deformation limits and to not elastically deform at a given application embodiment&#39;s temperature, time and chemical exposure limits. These requirements apply also to all other components except the PCB and cable of electronic sensor unit  100 . In certain embodiments, the clamp can be made from polycarbonate material. 
       FIG. 10  schematically shows a prior art proximal connector section  126  that can be attached to sensor unit  100  in order to connect the sensor unit to a plastic or rubber tube. The proximal end  126   a  is a hollow tube having a uniform diameter inner surface and tapered outer surface with several circumferential ledges created on it. In this embodiment proximal end  126   a  is dimensioned to fit into and firmly grip the inside of the distal end of elastomeric tubing, thereby firmly attaching proximal connector section  126  to the tubing. In other embodiments the proximal end  126   a  can have a different structure, depending on the type of conduit to which the sensor unit is to be attached. In this embodiment the central portion of proximal connector section  126  comprises a sample port  128 . 
     In certain embodiments, the proximal end  152  of body section  130  is a hollow tube whose outer diameter is dimensioned to fit into the distal end  126   b  of connector section  126 . An adhesive between the inner diameter of proximal end  126   b  and the outer diameter of distal end  152  can be used to create a leak proof connection holding the distal connector section  126  and body section  130  firmly together. 
       FIG. 11  shows an auxiliary distal connector section  148  that can be attached to sensor unit  100  in order to connect the sensor unit to a conduit through which the fluid continues to flow after passing through the sensor unit  100 . In the embodiment shown, the proximal end  148   a  of auxiliary distal connector section  148  is a cylindrical tube having an outside diameter dimensioned to fit inside of the distal end  154  of body section  130 . 
     An adhesive layer between the inner diameter of distal end  154  and the outer diameter of proximal end  148   a  can be used to create a leak proof connection holding the distal connector section  148  and body section  130  firmly together. The distal end  148   b  of distal connector section  148  is configured to connect to a conduit through which fluid continues to flow after passing through the sensor unit  100 . 
     Sides  182  that are part of distal auxiliary connector section  148  over distal end  148   b  are formed to fit tightly over and firmly grip the conduit through which the fluid continues to flow after passing through the sensor unit  100  to form a leak proof connection between auxiliary distal connector section  148  and the conduit. An adhesive further ensures against leakage. In this embodiment, the tops of sides  182  are curved to form the sides of an open channel  184  through which cable  142  passes into a dedicated lumen of a double-lumen tube. The sides of channel  184  are configured to grip said cable lumen of a double-lumen tube. 
     Embodiments of the conduit through which the fluid continues to flow after passing through the sensor unit  100  comprise double-lumen tubing in which one lumen is connected to distal end  148   b  of distal auxiliary connector section  148  as described above. Cable  142  passes through the second lumen, the proximal end of which is firmly gripped by the sides of open channel  184 . This embodiment is advantageous in many applications, for example when the sensor unit is used inline in a urinary catheter. In this application it allows convenient guiding of the cable away from the patient providing greater comfort to the patient and greater convenience to the nurses. 
     It is noted that in some embodiments the sensor unit can be manufactured as an integral component of a conduit rendering one or both of proximal connector section  126  or auxiliary distal connector section  148  unnecessary. 
       FIG. 12  shows an embodiment of the cover  132  of sensor unit  100 . During assembly, after PCB  140  and gasket  140  have been inserted into body section  130  and held in place by clamp  146 , and cable  142  is electrically connected to the PCB, cover  132  can be slid over the assembled body section  130 . Proximal end  132   a  of cover  130  then snaps onto proximal wall  152   a  of body section  130  and distal end  132   b  of cover  132  snaps into distal wall  154   a  of body section  130 . In one embodiment, inside the opening on the front of distal end  132   b  of cover  132  over cable guide  158  (see  FIG. 3 ) there is a tab (not shown) that presses down on the cable in cable guide  158  to provide strain relief preventing the cable from being pulled and disconnected from PCB  140 . 
     Another feature of embodiments of electronic sensor unit  100  is the plug at the distal end of cable  142  that electrically connects the circuit on PCB  140  with a control unit. In the embodiment described here, the plug is a modular connector, commonly known as a Registered Jack connector. In this embodiment an 8P8C modular connector, commonly known as RJ45 plug, of the type that is commonly used to connect telecommunications or data equipment, is used. In  FIG. 13  a PCB  186  is shown, which is dimensioned to fit wholly or at least partially inside the RJ45 connector, making its presence unobtrusive. The entire RJ45 plus PCB assembly can be over-molded making a convenient and conventional-appearing plug. 
     In the embodiment described herein, cable  142  comprises three wires and shielding. Instead of crimping exposed ends of the wires in cable  142  directly to the pins as is done in a conventional RJ45 plug, the conductors are electrically connected (e.g., soldered) to four pads  194  on PCB  186 . Metal traces on the PCB conduct electricity to conducting pads  190  to which pins  188  are electrically connected, e.g., by soldering, welding, or gluing with electrically conducting epoxy glue. These pins are positioned and dimensioned to match the channels in a modular connector and are firmly crimped into position using the usual tools and techniques associated with modular connectors. Following this step, the entire assembly can be over-molded to provide a finished appearance. 
     PCB  186  also includes an electronic circuit  196  that comprises, in this embodiment, inter alia a passive memory component. This circuit comprises, in this embodiment, inter alia, product information identifying the model number, date of manufacture, etc. of the electronic sensor unit  100  and usage data that can be used to manage various aspects of the sensor unit&#39;s operation, e.g., store accumulated data and/or control the amount of time that the electronic sensor unit  100  can be used, e.g. to prevent performance degradation or to enforce compliance with good practices. Other embodiments may include active components that operate the sensor(s), accumulate data, perform operations thereon, communicate with other systems and so forth. In other embodiments other numbers of wires may be connected to PCB  186 . This PCB design may be applied in any application wherein a modular connector of any sort is used on a cable and an unobtrusive inline electronic circuit is desired. 
     The dimensions and the distal and proximal connector sections of sensor unit  100  can be adapted mutatis mutandis to enable insertion or integration of the sensor unit into a conduit of any size for a wide range of applications. For example, the proximal connector section of sensor unit  100  described herein above can be connected to an indwelling urinary catheter inserted into the bladder of a bedridden patient and the distal connector section of sensor unit  100  connected to tubing that leads to a urine collection container. In this application, sensor unit  100  can be used for urine monitoring. In food production the sensor unit can be used to check that a liquid ingredient is fully homogenized by placing sensors at various depths to see if they all give the same reading. In an automotive exhaust, pipe sensor units can be placed to check emission levels or other properties of the gases. In an open conduit of fixed orientation, wherein liquid flows (or a closed conduit where the liquid may not entirely fill the conduit), sensor units may be mounted on sensor support in the floor and/or projecting up into the liquid flowing therein to measure presence or properties of the fluid at various depths. Other examples of such applications include pipes or conduits for wine in a wine bottling plant, for molten chocolate in a candy factory, for molten steel in a foundry, for molten plastic in an extrusion application, for water in an irrigation canal or a drainage ditch, and others. 
     It is noted that the elements of the electronic sensor unit are constructed, for example with snap-fit features, that enable the sensor to be disassembled and reassembled on as-needed basis for medical procedures, adjustments, and repair. 
     Although embodiments of the invention have been described by way of illustration, it will be understood that the invention may be carried out with many variations, modifications, and adaptations, without exceeding the scope of the claims.