Embodiments are generally related to sensors and, more particularly, to pressure sensors and methods of manufacturing such sensors. Embodiments are additionally related to disposable pressure sensors and to disposable pressure sensor systems for use in medical and other applications. Additionally, embodiments are related to disposable pressure assemblies for use with disposable fluid carrying modules, such as fluid cartridges and tubing used in medical applications.
In single-use type applications, such as for example medical systems and instrumentation where re-use of sensors is unfavorable due to cleaning and sterilization requirements, disposable sensors are required which can be implemented in a cost-effective manner.
Electronic packages for sensors generally have a base level of packaging for housing the sensor followed by further levels of packaging for housing electrical and mechanical connections which are required so that the sensor can be properly interface with the device. Typical sensor assemblies/packages are therefore not particularly well suited to such applications by virtue of the relatively high number of component parts, expensive materials and/or processing requirements, and high number of manufacturing-processing steps required to both produce packaged sensors and to integrate them into the instrumentation or apparatus of the application.
Pressure sensing solutions, particularly for disposable sensors, are therefore required to provide an ultra low cost assembly which can be integrated more easily and more cost effectively into the final application or system.
The embodiments disclosed herein therefore directly address the shortcomings of present pressure sensors providing low cost disposable pressure sensor assemblies and packaging associated therewith which can be integrated into instrumentation and other equipment simply and cost effectively.
The following summary is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
It is, therefore, one aspect to provide for an improved disposable package for pressure sensors.
It is another aspect to provide for a disposable pressure sensor.
It is yet another aspect to provide for disposable pressure sensor systems for use in medical applications, such as blood pressure sensing.
It is yet another aspect to provide for a method of forming a disposable pressure sensor system.
The aforementioned aspects and other objectives and advantages can now be achieved as described herein. A disposable package for a pressure sensor is disclosed. The package has a housing or frame for carrying at least one sensing element thereon and at least one mechanical and/or electrical connector for connecting the sensing element(s) to an external apparatus. The one or more connectors are integrated in the housing so that both the connector(s) and sensing element(s) are packaged in a single part.
By incorporating the sensing element(s), such as pressure sensor die(s), on the same frame or housing as the electrical connector, many of the parts and electrical connections necessary to make the sensor are eliminated. For example, a separate dedicated housing is no longer required to accommodate the sensor. Furthermore, incorporating the electrical connector on the frame eliminates the need to provide a separate cable connector assembly for electrically connecting the sensor to a cooperating connector of the external apparatus. Also, a plurality of sensing elements can be attached to the same housing. Consequently, the sensor system can be manufactured with less parts and associated processing steps thereby enabling a low cost sensor system to be provided.
The one or more mechanical connectors can be in the form of mechanical connection(s) integrally formed in the housing or frame for connecting the sensor to a fluid carrying module, such as a dialysis cartridge. Alternatively or additionally, the housing can include integrally formed mechanical and/or electrical connections for connecting the sensor(s) to a measurement apparatus for measuring the output signals of the sensor(s). The disposable package can include one or more windows or ports, also integrally formed in the housing, for transmitting a fluid pressure to the sensing element(s) which can be, for example, pressure sensing elements. One or more sealing interface surfaces or connectors for sealing the housing window(s) or port(s) to corresponding fluid ports of a device can also be integrated in the housing.
The housing or frame can be a molded plastic part having a patterned metalized layer so as to form the electrical connections required to incorporate the sensor into the application.
According to another aspect a disposable pressure sensor system has a disposable sensor assembly which has one or more sensing elements carried on a housing or frame. One or more electrical and/or mechanical connectors for connecting the sensing element(s) to an apparatus or device are integrated in the housing. Also integrated in the housing, can be a window or port for transmitting a fluid pressure to the sensing element(s). One or more sealing connections can be integrated in the housing for sealing the housing to a device such that the sensing element(s) can detect pressure of fluid held or flowing through the device.
One or more of the mechanical connectors can be a mechanical connection for securely attaching the pressure sensor assembly to a fluid carrying module and/or measuring apparatus.
The disposable pressure sensor system can include a fluid carrying module, such as a cartridge for a dialysis machine, and one or more of the mechanical connectors integrated in the housing can be a mechanical connection configured to cooperate with a corresponding connection on the fluid carrying module. For example, the mechanical connections of a cartridge and the housing can be configured such that the pressure sensor assembly is snapable or latchable to the cartridge.
If necessary, the housing or frame can be integrated with the fluid carrying module. The fluid carrying module can be, for example, a catheter tube or a dialysis cartridge. One or more trim components can be carried on the housing and electrically connected to the sensing element(s) for adjusting or offsetting an output signal of the sensing element(s). The sensing element(s) can be reactive ion etched diaphragm(s) further reducing the pressure sensor system cost.
According to yet another aspect, a method of forming a disposable pressure sensor system comprises forming a housing or frame, integrally forming a connecting portion in the frame, depositing conductive material on the connecting portion so as to integrate at least one electrical connector in the housing, attaching at least one pressure sensing element on the housing, and electrical connecting sensing elements to the conductive material.
The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.
Referring to
In the embodiment shown in
Housing 3 includes a panel 5 which serves as a supporting substrate for sensing elements 4 attached to the rear face 23 of the panel by means of a suitable bonding material, such as room temperature vulcanizing Silicone (RTV). Sensing elements 4 are arranged to be in communication with corresponding windows or inlets 14, formed in the panel 5, for transmitting fluid under pressure so as to expose one side of the sensing element(s) to the fluid 8 and the other side to a reference pressure 24, for example atmospheric pressure.
Panel 5 also includes mechanical connections 21 for securably attaching the pressure sensor assembly 2 to the module 16 in an operating position in which inlets 14 are contiguous with corresponding outlets 9 of the module such that the sensing elements can detect fluid 8 transmitted thereto from respective chambers 18. Sealing interface surfaces 25 formed on the panel 3 have respective ‘O’ rings 7 seated therein for sealing the inlets 14 to the corresponding outlets 9.
In this particular embodiment, the peripheral edge of the panel 5 forms the mechanical connection 21 which is latchable onto the module 16 by means of a pair of latching arms 20 extending perpendicularly from opposite sides of the module rear face 29. However, the pressure sensor assembly 2 can be connected to the module 16 using other techniques, such as for example by ultrasonic or laser welding or bonding the mechanical connections 21 to the module. Furthermore, structure other than or in addition to sealing interface surfaces 25 can be incorporated into the housing for sealing the inlets 14 to the outlets 9, such as for example flanges, threaded ports or clips.
Circuitry of the sensing elements 4 are electrically connected by means of wire bonding 10 to metalized plastic contact pads (not shown) which, in turn are connected to metalized plastic electrical interconnects or traces 27. Housing 3 also includes arms 6, extending perpendicularly from panel rear 23, having electrical terminals 11 carried thereon so as to define an electrical connector 30. Electrical terminals 11, electrically coupled to wire bonding 10 by means of the electrical interconnects 27, are arranged for electrical connection to corresponding mating connections of a measurement apparatus (not shown) to which pressure sensor assembly 2 is attachable. Mechanically attaching the pressure sensor assembly 2 to the measurement apparatus causes the electrical terminals 11 to mate with the corresponding mating connections of the measurement apparatus such that outputs signals of the sensing elements 4 can be provided to the measurement apparatus for signal conditioning and processing.
In this particular embodiment, electrical terminals 11 and interconnects 27 are formed by deposition of conductive material onto the housing 3, for example using metal deposition processes known in the art, such as Exact™ process developed by Cybershield, or alternatively, direct write processes such as inkjet for deposition of metals and conducting polymers/composites. Deposition of conductive materials could also be used to create ground plain metallization and other similar methods of screening radio-frequency interference from the sensors.
Electrical connectors 30 shown in
The sensing elements 4 shown in the illustrative embodiment of
Each PZR-Si sensing element 4 shown in
Alternatively, resistors 13 can be replaced with a single thick film resistor whose resistance can be modified by exposure to a laser (i.e. a laser trimmable resistor).
External trim components, such as resistors 13, can be omitted if on-chip trimming is achieved using, for example, chrome-silicon (CrSi) resistors deposited directly on the silicon pressure die in order to allow fewer component parts and lower overall sensor cost. Such on-chip trimming processing can be performed for example by laser trimming the sensor die while in wafer form or after attachment of the sensing element to the housing, thereby allowing for compensation of packaging induced offsets.
A protective cover 12 or cap, clipped or bonded to the panel rear over the sensing elements 4 and circuitry, can be employed to provide the sensing elements and circuitry mechanical protection. If sensing elements and circuitry require protection from liquid and/or gases or from compounds, particles, impurities associated therewith, such as for example in a steam sterilization process, the cover 12 could be sealed in place, for example using an ‘O’ ring, RTV, epoxy, or adhesive. Where a reference to a pressure media 24 such as atmosphere is required, as is the case in the illustrative embodiment of
If required, passivation of circuit traces 11,27, wire bonds 10 and/or sensing elements 4 can be employed to prevent exposure of such parts to liquid/gas in the local environment and/or cleaning fluids. For example, a PTFE (Teflon) coating technique, known in the art, like that offered by GVD corporation, Massachusetts, could be used. Alternatively, gel fill material, such as silicone gel, can be applied as is standard in the art to provide physical and/or electrical isolation of the sensing element and/or electrical connections and/or die attach material from the media and/or reference environment.
Furthermore if isolation from EMI is required, cover 12 could be metallized and, if necessary conductive adhesive can be used to connect this to a common point on the metallization of the plastic housing. Cover 12 can also support a label or even a smart label, such as RFID tag, as required to provide various data/data storage for use with the assembly.
Preferably, for ease of production assembly, the pressure sensor assembly is manufactured utilizing reel-to-reel processing such as disclosed in United States Patent Application Publication No. US2005/013659 A1 of Shiffer et al, published on Jun. 23, 2005 and entitled “Plastic Lead Frames Utilizing Reel-to-Reel Processing” which is incorporated herein by reference. A plastic part or substrate is transported on a carrier for manufacturing of the pressure sensor assembly based on the initial part. A reel-to-reel mechanism permits a plurality of manufacturing operations, such as plastic molding operations to form the housing and circuit configuring operations to form the circuitry, to be implemented upon the initial part to create the final pressure sensor assembly.
Preferably, housing 3 is run through a fully automated assembly line in which the metallization process is followed by attachment of the sensing element (RTV/ epoxy/flip chip bonding), wire bonding 10 or other forms of conductive bonding, such as anisotropic conductive adhesive, to make electrical connection to the sensing elements 4, followed by fitting of components and/or calibration/trim/test, followed by passivation and/or attachment of protective cap 12. Assembled parts are kept in reel form to feed into the assembly line for the whole system e.g. OEM manufacturing line, such as that used for manufacture of disposable cartridges/cassettes where the low cost sensor assembly could then be singulated and clipped and sealed into place.
Referring now to
As best illustrated in
The disposable housing 302 and permanent equipment 350 can have alternative mechanical and/or electrical connections to those shown in
A pressure sensor system according to yet another embodiment is illustrated in
Electrical connections 411 in the form of conductive traces or interconnects, formed on the frame upper side 451, extend away from the pressure sensor interconnects 461 to the frame distal end 452 which is configured to be insertable into a receiving passageway of an electrical female connector 430 of a measurement apparatus. Frame 405 together with electrical connections 411 define a plastic lead frame 405,411. The frame 405 and electrical connections 411 define an electrical connector 406 for electrical connection with a corresponding connector 430 of a measuring apparatus for measuring the output signals of the pressure sensor.
A stop valve 470 for controlling flow of fluid into the flow tube 416 is also integrally formed in the flow tube as are various push on fittings 471-473 for receiving associated tubing fastened thereon using tube grips or clamps 474.
In the illustrative embodiment of
By incorporating the frame 405 into the flow tube 416 or other fluid carrying part, separate mechanical connectors or connections for connecting the pressure assembly to the fluid carrying part, need not be provided. Also by incorporating the pressure sensor die on the plastic lead frame 405,411, many of the parts and electrical connections necessary to make the pressure sensor assembly are eliminated. For example, a separate dedicated housing is no longer required to accommodate the pressure sensor. Furthermore, incorporating the electrical connector on the frame eliminates the need to provide a separate cable connector assembly for electrically connecting the sensor to the female connector. Consequently, the pressure sensor system can be manufactured with less parts and associated processing steps thereby enabling a low cost pressure sensor system to be provided.
The description as set forth is not intended to be exhaustive or to limit the scope of the invention. Many modifications and variations are possible in light of the above teaching without departing from the scope of the following claims. For example, those skilled in the art would understand that the metalized plastic housing having integrated electrical and mechanical connectors, as shown in the illustrative embodiments herein, could be applied to other sensing systems, such as for example temperature, speed and position sensing systems. It is contemplated that the use of the present invention can involve components having different characteristics. It is intended that the scope of the present invention be defined by the claims appended hereto, giving full cognizance to equivalents in all respects.
The embodiments and examples set forth herein are presented to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and utilize the invention. Those skilled in the art, however, will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. Other variations and modifications of the present invention will be apparent to those of skill in the art, and it is the intent of the appended claims that such variations and modifications be covered.
This application is a continuation of U.S. patent application Ser. No. 11/357,497, filed Feb. 17, 2006, and entitled “DISPOSABLE PRESSURE SENSOR SYSTEMS AND PACKAGES THEREFOR”, which is hereby incorporated by reference.
Number | Date | Country | |
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Parent | 11357497 | Feb 2006 | US |
Child | 13107622 | US |