Patent Abstract:
The vacuum desiccator low pressure vacuum pump and trap and is transportable upon a user&#39;s person. The device is especially useful to remove excess fluids from wounds and incisions as they heal. The device includes a desiccator cartridge containing a fluid trapping agent. The desiccator cartridge is connected to a vacuum pump member providing a low vacuum pressure to the interior chamber of the desiccator cartridge. A small battery powered, electric motor drives the pump member. An electrical control circuit, including the battery power source, controls the operation of the electric motor. A single passage, one-way, gas/liquid flow pathway connects the inlet port of the desiccator cartridge to an occlusive dressing covering the wound to be drained. The control circuit includes one or more ancillary circuits for controlling operation of the device, such as: a power circuit, a moisture sensor, a timer circuit, a vacuum pressure sensor, and a pressure differential sensor.

Full Description:
FIELD OF THE INVENTION 
     The present invention is in the field of portable, motor driven vacuum p-umps having a movable working member which is motivated by electricity or a magnetic field. More specifically, the present invention relates to a personally portable, low negative pressure, motor driven vacuum pump having an electric power storage means and a moisture trap. 
     BACKGROUND OF THE INVENTION 
     A number of portable, low pressure vacuum apparatuses capable of producing vacuum pressures down to about 500 mm HG currently exist. Medicine, particularly the wound healing arts, is a field where such devices have a specific utility. In the wound healing arts, it has been recognized that the removal of excess fluid from a wound site can improve the healing of the wound. This recognition has motivated the field to develop wound treatment regimens that include the use of vacuum devices for removing excess exudate from a wound site. For example, in full thickness dermal wounds devices to assist in the removal of excess fluid from these wounds have been developed and used. Further, because of the recognized benefits of encouraging patients to be active and mobile if possible, these devices need to be portable, and preferably, personally portable. 
     One strategy for providing a personally portable, low pressure vacuum source for drainage of wound site involves the use of a passive vacuum reservoir. Examples of this types of device includes those disclosed by Fell, U.S. Pat. No. 5,073,172; Seddon et al., U.S. Pat. No. 6,024,7311 and Dixon et al., U.S. Pat. No. 5,944,703. Typically, these devices comprise an evacuated cannister attached to a drainage tube. Because the vacuum pressure in the reservoir of these devices continuously decreases as the wound is drained (and the reservoir filled), they often include a means for regulating the pressure delivered to the wound site at some level below the maximum pressure of the vacuum reservoir. Additionally, these devices require a reservoir of a relatively larger volume than that of the volume of fluid they are capable of removing from a wound site. 
     Recognizing these limitations, the field has been further motivated to develop means for providing a portable, low pressure vacuum source for drainage of a user&#39;s wound site which provides a relatively constant vacuum pressure. A strategy for accomplishing this objective includes having the device comprise a vacuum pump to provide a constant low pressure vacuum source, or to replenish a separate vacuum reservoir. An example of this type of device includes that disclosed by McNeil et al., U.S. Pat. No. 4,710,165. Also see U.S. Pat. No. 5,134,994 to Say. Although portable, these devices are bulky and obvious to an observer of the user, and may subject the user to embarrassment or personal questions. It would be beneficial to have a portable vacuum device that was personally portable by the user without being obvious to an observer. 
     An apparatus which addresses this latter benefit is disclosed in U.S. Pat. No. 6,142,892 to Hunt et al. The Hunt apparatus is supported on a belt or harness worn by the user, and is small enough to be unobtrusive when worn under a jacket or the like. However, the Hunt apparatus utilizes a liquid reservoir containing the fluids drained from a wound site. Fluids contained in the liquid reservoir of Hunt are subject to slouching, which may adversely affect the function of the Hunt apparatus if the fluid prematurely enters an inappropriate pathway (the outlet end of the cannister). Also, the Hunt device requires multiple tubes or a multi-lumen tube running from the device to the wound site to accomplish its full utility. Additionally, the Hunt apparatus is intended to be worn by a patient at waist level or higher. This means that wound sites below and distal to the users waist can be subjected to a higher vacuum pressure than with a device that may be located more proximal the wound site than the Hunt apparatus. 
     Although the above apparatuses may be useful in the field for accomplishing their intended purposes, it would be beneficial to have an alternative personally portable vacuum device that can be worn unobtrusively by the user, and which is not subject to slouching of the fluid it retains, and further which does not require special tubing to connect it to a wound site. 
     SUMMARY OF THE INVENTION 
     The present desiccator is a personally portable vacuum pump and moisture trapping device. The invention is useful where a user desires to carry a device for collecting and trapping small volumes of liquids. As a specific example, the present invention is therapeutically useful to provide a personally portable low negative pressure source and trap for aspirating and collecting fluid exudate from a wound or incision. A further benefit of the present invention for such applications involving biological waste is that the trap and all other components of the desiccator device that contact the aspirated biological materials are removable from the device and are replaceable. The desiccator device includes a trap, a vacuum pump head member, an electric motive mechanism and an electric control and power circuit. 
     The trap comprises a desiccator cartridge enclosing an interior space or chamber. An inlet port and an outlet port provide gas/liquid flow communication with the interior chamber of the desiccator cartridge. The desiccator cartridge is of a design and construction to withstand the application of an appropriate vacuum without substantial collapse of the interior chamber. Some distortion of the cartridge while under vacuum is desirable in some applications, e.g., where buffering of the vacuum pressure of the system is beneficial. A trapping agent is contained within the interior chamber for retaining the fluid that enter the chamber. The composition of the trapping agent is selectable by one of ordinary skill in the art in view of the teaching herein and in consideration of the characteristics of the fluid to be trapped. 
     A vacuum pump member or pump head is connected in gas flow communication with the interior chamber of the trap by having the low pressure port of the vacuum pump member being connected to the outlet port of the trap. The exhaust port of the vacuum pump member is vented to atmosphere. Operation of the vacuum pump member develops a low vacuum pressure which is communicated to the interior chamber of the desiccator cartridge and then to the inlet port of the trap. The vacuum pressure at the inlet port of the trap is selectable by the ordinary skilled artisan depending on the intended use of the present device. Typically, the selected vacuum pressures range less than about 250 mm Hg, and in part depends on the vacuum pressure to be delivered to the wound site and the any loss of vacuum pressure across the delivery tube connecting the inlet port to the wound site. An electric motive means (an electric motor) is coupled to the vacuum pump member and drives the pump head. An electrical control circuit, including an electrical power source, is in electrical communication with the electric motive means. The control circuit is operable to control the operation of the electric motive means. 
     The desiccator cartridge of the trap has only a single, ingress gas/liquid flow pathway, which is the inlet port. Additionally, the flow path at the inlet port is unidirectional, in that gas/liquid flow can enter the trap via the inlet port, but not exit or back flow out of the trap via the inlet port. Optionally, the personally portable vacuum desiccator includes a single passage gas/liquid flow path delivery tube for connecting the trap to a source of gas or liquids to be delivered into the trap. The delivery tube has an input end for communicating with the gas/liquid source and an output end connectable to the inlet port of the desiccator cartridge. A one-way valve is located proximate the inlet port of the desiccator cartridge. The one-way valve prevents the contents of the desiccator cartridge from back-flowing out of the inlet port. The one way valve may be separate from or incorporated into the inlet port. The desiccator cartridge is removable from the vacuum desiccator and separately disposable. A fresh desiccator cartridge is installed in the desiccator to replace the removed cartridge. 
     The desiccator cartridge contains a trapping agent for containing the liquids or moisture delivered to the trap under the force of the vacuum. The trapping agent combines with the liquid or moisture to alter its physical features, i.e., from a liquid or vapor to a mixed phase or solid state. Compositions suitable for use as trapping agents in the present invention are selectable by one of ordinary skill in the art in view of the present disclosure and teachings herein. The trapping agent should adsorb, absorb or in some way combine with the liquid or moisture to immobilize and keep it from sloshing in the desiccator cartridge as it is accumulated in the interior chamber. Examples of potentially suitable trapping agents include: a desiccant, an adsorbent and an absorbent. Specific examples include silica gel, sodium polyacrylate, potassium polyacrylamide and related compounds. Such moisture trapping materials are often found in disposable baby diapers and in feminine napkins. The level of moisture in the desiccant chamber is monitored by the moisture sensor circuit. When the amount of moisture trapped in desiccant material approaches saturation, the chamber may either be removed and disposed of or recharged with fresh desiccant material and repositioned in the device (depending on the design of the desiccator cartridge). 
     The present vacuum desiccator can further comprise a filter for blocking bacteria and/or untrapped moisture from passing into the vacuum pump member or from being vented to atmosphere. The filter may be located proximate the outlet port to protect the pump member and/or proximate the exhaust port to prevent venting bacteria or moisture to atmosphere. 
     The electric motive means of the vacuum desiccator includes an electric motor. The motor is coupled to the vacuum pump member to drive the pump. The motor may be coupled to the pump head by any of a number of means known to and practicable by the ordinary skilled artisan. For example, the motor shaft may be integrated with the vacuum pump head, it may be mechanically coupled to the vacuum pump so as to be readily separable from the pump head, or it may be magnetically coupled to the pump head so as to, again, be readily separable from the vacuum pump member. A readily separable motive means is particularly useful where the vacuum pump member and the desiccator cartridge are integrated together as a unit. 
     A purpose of the electrical control circuit is to monitor the condition of the device and to control operation of the motive means. The electrical control circuit includes the electrical power source for the device. The power source comprises an electrical power storage means, such as a battery. A feature of the power source is that the electrical storage means is removable from the electrical control circuit and is replaceable. Additionally, the electric control circuit optionally includes other ancillary circuits for the operation and control of the device. These circuits include: a moisture sensor circuit for detecting the presence of moisture proximate the low pressure port of the vacuum pump member; a timer circuit for intermittently operating the electric motive means; a vacuum pressure sensor circuit for detecting a vacuum pressure in the interior chamber or elsewhere in the device; and a pressure differential sensor circuit for sensing a difference in pressure between the inlet and outlet ports of the desiccator cartridge. 
     The component parts of the vacuum desiccator device which are in gas/liquid flow communication are replaceable. This allows the components of the device which are exposed to contact with the wound fluids to be separable from the other components of the device to facilitate cleaning or disposal of contaminated components. 
     The present personally portable vacuum desiccator can further comprise a housing for containing some or all of the component parts of the device. For example, the housing may contain the electric motive means and the electrical control circuit, while the other components are simply attached to the housing, e.g., an integrated pump head/trap combination assembly. Other configurations obviously are possible, such as a housing containing the electric motive means and the electrical control circuit and additionally either or both of the trap (desiccator cartridge) and the vacuum pump member. 
     Additionally, the present vacuum desiccator device may comprise the battery being housed in a battery compartment attached or integral to the desiccator cartridge of the moisture trap. In this configuration, the battery and the desiccator cartridge are replaceable in the device as a single unit. 
     It is a feature of the present invention that the personally portable vacuum desiccator can be used as part of a treatment regimen to promote wound healing by drawing excess wound exudate away from the wound site. As an example of using the desiccator for this purpose, an open, full thickness dermal wound is covered with an air tight dressing, such as are commercially available. The input end of the gas/liquid flow delivery tube is positioned under the dressing in flow communication with the wound site. The vacuum desiccator is activated, a low negative pressure is produced at the wound site via the delivery tube and excess fluids excreted by the wound are removed under the force of the low negative pressure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of the major components of the present vacuum desiccator showing the electric control circuit contained in a housing with the motor coupled to the trap and vacuum pump member. 
         FIG. 2A  is a side elevation and partial cross-sectional view of the desiccator cartridge of the present device, showing the interior chamber containing a trapping agent. 
         FIG. 2B  is a top plan and partial cross-section view of the desiccator cartridge showing the interior chamber containing alternative trapping agents and showing alternative moisture/fluid sensors for detecting fluid in flow path proximate the outlet port of the cartridge. Also shown is a separately mountable outlet microfilter. 
         FIG. 3  is a partial top plan view of the outlet port portion of the desiccator cartridge showing in phantom a micro-filter integral to the desiccator cartridge flow path, and also a vacuum pressure sensor mountable to the outlet port of the cartridge. 
         FIG. 4  is a cross-sectional view through a side elevation of a combination of a desiccator cartridge and vacuum pump head as an integral unit. 
         FIG. 5A  is a partial top plan view of the inlet portion of the desiccator cartridge showing the inlet port with a one-way gas/fluid flow valve installed. 
         FIGS. 5B and 5C  are partial cross-sectional views of two types of one-way gas/liquid flow valves. 
         FIG. 6  is a block diagram of the electric control circuit of the desiccator device indicating its sub-circuits and the interconnect relationship with certain ancillary components. 
         FIGS. 7A and 7B  show alternative strain-gauge means for monitoring vacuum pressure in the interior chamber of the desiccator cartridge. 
         FIG. 8  is a partial cross-section of a side elevation of a desiccator cartridge showing the interior components and their layout. 
         FIG. 9A  is an exploded view of a side elevation of a desiccator cartridge showing a cover member incorporating an integral gas flow channel. 
         FIG. 9B  is a bottom plan view of the cover member of  FIG. 9A  illustrating an example of an integral gas flow channel layout (in phantom) and the perforations by which the integral channel is in gas flow communication with the interior chamber of the desiccator cartridge. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The personally portable vacuum desiccator is a device useful as a source for providing a low vacuum pressure for removing excess wound exudate from dressed dermal wounds. This application of present personally portable vacuum desiccator is useful for promoting wound healing by draining such excess wound exudate from the wound site. 
     Referring now to the drawings, the details of preferred embodiments of the present invention are graphically and schematically illustrated. Like elements in the drawings are represented by like numbers, and any similar elements are represented by like numbers with a different lower case letter suffix. 
     As shown in  FIG. 1 , the present invention is a personally portable vacuum desiccator  10  comprises a trap  12 , a vacuum pump member operable to provide a source of low vacuum pressure, an electric motive or drive means  36  for operating the vacuum pump member, and an electrical control circuit, including an electrical power source. The control circuit is electrically connected to the electric motive means to control its operation, i.e., to turn it on and off. The trap  12  includes a desiccator cartridge  14  The desiccator cartridge  14  has an interior chamber  16  containing a trapping agent  54  (see  FIG. 2 ). Additionally, the desiccator cartridge  14  has an inlet port  18  and an outlet port  20  in gas/liquid communication with the interior chamber  16  of the cartridge  14 . A vacuum pump head or member  22  serves as a source for a low pressure vacuum of about 250 mm Hg or less. The vacuum pump member  22  is placed after desiccant chamber  14  in the gas/liquid flow pathway to facilitate preventing fluid from entering the vacuum pump member. The vacuum pump head  22  has a low pressure port  24  and an exhaust port  26 . The low pressure port  22  is in gas/liquid flow communication with the outlet port  20  of the desiccator cartridge  14 . The exhaust port  26  of the vacuum pump head  22  is vented to atmosphere. When operated, the vacuum pump member  22  provides a low vacuum pressure to the interior chamber  16  of the desiccator cartridge. As further shown in FIG.  1 ., an electric motive means  36  is in communication with the vacuum pump member  22  via a coupling  38 . The electric motive means  36  is a low voltage electric motor, which is operable to drive the vacuum pump member  22 , thus providing a low vacuum pressure at the pump member&#39;s low pressure port  24 . The electrical control circuit  40 , including an electrical power source  46 , is in electrical communication with the electric motive means  36  via an electric motor lead  42 . The control circuit  40  controls the operation of the electric motive means. 
     Optionally, a delivery tube  32  is included with the desiccator device  10  to put the trap  14  in gas/liquid flow communication with a location to which a low negative vacuum pressure is to be applied, such as a wound site covered by an occlusive dressing (not shown). The delivery tube  32  consists of a single passage gas/liquid flow path, having an input end  33  and an output end  24 , the output end  34  being connected to the inlet port  18  of the desiccator cartridge  14 . 
     The components of the personally portable vacuum desiccator  10  can further comprise a housing  50  for containing or mounting the component parts of the vacuum desiccator  10 . As exemplified in  FIG. 1 , the housing  50  contains the electric motive means  26  and the electrical control circuit  40 . Alternatively, the housing  50  can contain the electric motive means  36 , the electrical control circuit  40  and additionally, the desiccator cartridge  14  and/or the vacuum pump member  22 . 
     The trap  12  comprises a desiccator cartridge  14 . As shown in  FIGS. 2A and 2B , the desiccator cartridge  14  encloses an interior space or chamber  16 . The desiccator cartridge  14  is of a design and material construction to withstand the application of an appropriate vacuum without substantial collapse of the interior chamber  16 . Some distortion of the cartridge while under vacuum is desirable in some applications, e.g., where buffering of the vacuum pressure of the system is beneficial or distortion of the chamber  16  is used as an index of the vacuum pressure within the interior chamber  16 . 
     A trapping agent  54  is contained within the interior chamber  16  to retain (trap) fluids and moisture that enter the chamber  16 . There are a variety of compositions available in the art that are appropriate trapping agents for practice in the present invention. A specific composition or combination of compositions useful as the trapping agent  54  is readily selectable by one of ordinary skill in the art in view of the teaching herein and in consideration of the characteristics of the fluid to be trapped. Examples of classes of such compositions suitable as trapping agents  54  include desiccants, adsorbents, absorbents and the combination of any of these. Specific examples include silica gel, sodium polyacrylate, potassium polyacrylamide and related compounds. Such moisture trapping materials are often found in disposable baby diapers and in feminine napkins. These compositions may be particulate trapping agents  54 a or fibrous trapping agents  54 b. In a preferred embodiment, the trapping agent  54  was a pillow-like structure (see  FIG. 8 ), which included a fiber matrix material which served to contain and somewhat immobilize the other loose components of the trapping agent, and to act as a wick to distribute the fluid as it entered the interior chamber. The level of moisture in the interior chamber  16  proximate the outlet port  20  is monitored by a moisture sensor  84  (see  FIG. 1 ). When the amount of moisture retained by the trapping agent  54  approaches saturation (as detected by the moisture sensor  84  or indicated by other means), the desiccator cartridge  14  may either be removed and disposed of or recharged with fresh desiccant material and repositioned in the device (depending on the design of the desiccator cartridge). Other means for detecting the degree of saturation of the trapping agent  54  are available. For example, the desiccant cartridge  14  may be constructed in part from a transparent material, allowing the trapping agent  54  to be directly observed. The degree of saturation of the trapping agent  54  maybe indicated by a color change in a component of the trapping agent  54  in response, for example, to a pH change or degree of hydration. 
     In a preferred embodiment of the vacuum desiccator  10 , all of the components in gas/liquid flow communication are replaceable. This allows the components of the device that are exposed to contact with the wound fluids to be separable from the other components of the device to facilitate cleaning or disposal of contaminated components. In particular, the desiccator cartridge  14  is removable from the device  10  and separately disposable. A fresh desiccator cartridge  14  is installed in the desiccator  10  to replace the removed cartridge. Alternatively, the cartridge  14  can be constructed to make its interior chamber  16  accessible, e.g., through a lid or by disassembly, whereby the used trapping agent  54  can be replaced with fresh. The refreshed desiccator cartridge may then be reattached to vacuum desiccator  10 . This feature may be useful where the desiccator cartridge and vacuum pump head are combined as a single integrated unit (see  FIG. 4 ). 
     The desiccator cartridge  14  has a single, gas/liquid flow pathway, which is the inlet port  18 , as the only inlet path into the trap  12 . The flow path at the inlet port  18  is unidirectional, in that gas/liquid flow can enter the trap via the inlet port  18 , but not exit or back flow out of the trap  14  via the inlet port  18 . Unidirectional flow at the inlet port is accomplished by a one-way valve  30  located proximate the inlet port  18  of the desiccator cartridge  14  (see  FIG. 5A ). The one-way valve  30  prevents the contents of the desiccator cartridge  14  from back-flowing out of the inlet port  18 . The one-way valve  30  maybe separable from the desiccator cartridge  14 , as shown in  FIG. 5A , or it may be incorporated into the cartridge  14  proximate the inlet port  18  (not shown). One-way gas/liquid flow valves practicable in the present invention are known in the art and selectable by the ordinary skilled artisan for use in the present invention. Examples of such one-way valves include biased and/or unbiased piston-type  30 a and ball-stop  30 b valves as exemplified in  FIGS. 5B and 5C . 
     A micro-filter  28  useful for blocking bacteria and/or untrapped moisture from passing into the vacuum pump member or from being vented to atmosphere is located in the gas/liquid flow path of the device  10  after the interior chamber  16  of the desiccator cartridge. The micro-filter  28  may be located proximate the outlet port  20  to protect the pump member  22  and/or proximate the exhaust port  26  to prevent venting bacteria (or moisture) to atmosphere. The micro-filter may be an in-line micro-filter  28 a separate from the desiccator cartridge as shown in  FIG. 2B , or an integral micro-filter  28 b incorporated into the cartridge  14  proximate the outlet port  20  as shown in  FIG. 3 . 
     As shown in  FIG. 1 , an electric motive means  36  is coupled to the vacuum pump member  22  of the vacuum desiccator  10 . In the preferred embodiment, the motive means  36  is an electric motor. Electric motors practicable in the present invention are known to and selectable by one of ordinary skill in the art in view of the teachings and figures contained herein. For example, a miniature, oil-less diaphragm pump is commercially available from the Gast Manufacturing, Inc. (Michigan): series 3D 1060, model 101-1028. The electric motor  36  communicates with the vacuum pump member  22  via a drive coupling  38  to drive the pump. The drive coupling  38  for connecting the motor  36  to the pump head  22  may be accomplished by any of a number of means known to and practicable by the ordinary skilled artisan. For example, a motor shaft coupling  38  maybe integrated with the vacuum pump head, i.e., the motor  36  and pump member  22  are substantially a single unit. Alternatively, a motor shaft coupling  38  may be mechanically coupled to the vacuum pump head  22  so as to be readily separable from the pump head  22 . For instance, as exemplified in  FIG. 4 , the hub  100  of a rotary-vane pump head  22 a has a motor shaft receiver  102  for accepting the end or spindle of a shaft coupling  38  of a motor  36 . The shaft receiver  102  has a threaded, keyed or similar interfacing configuration (not shown) complementary to the spindle or end of the shaft coupling  38  of the motor  36 . As a further alternative, the motor  36  maybe magnetically coupled (not shown) to the pump head  22  so as to again be readily separable from the vacuum pump member  22 . A readily separable motive means  36  is particularly useful where the vacuum pump member  22  and the desiccator cartridge  14  are integrated together as a unit, as shown in  FIG. 4 . 
     As shown in  FIG. 6 , the present vacuum desiccator device  10  includes an electrical control circuit  40  that comprises logic and switching circuits and a number of ancillary circuits and functions, external sensors, electrical connections and a power source. In the preferred embodiment, the purpose of the electrical control circuit  40  is to monitor the condition of the device  10  and to control operation of the motive means  36 . The ancillary circuits can be chosen for inclusion in an embodiment of the device  10  to affect one or more of the following functions: device data Input/Output, electrical power, sensor signal processing and motor control (power to the motor). An I/O unit  70  for accomplishing device data input and out put can include data input means such as a power and data entry switches (e.g., a key pad and/or on-off switch), and a readout display and alarms. Such I/O units  70  are well known in the art, and are readily practicable in the present invention by the ordinary skilled artisan. Other ancillary circuits and other sensors  88  may be provided at the user&#39;s option, and are similarly accomplishable by the ordinary skilled artisan. 
     In the preferred embodiment exemplified in  FIG. 1 , the power source  46  for storing and providing electrical energy for the device  10  is a battery  60 . In the preferred embodiment, the power source  46  is removable from the electrical control circuit  40  and is easily replaceable. The POLAROID® P100 Polapulse™battery is an example of an appropriate battery  60  useful as a power source  46  in the present vacuum desiccator device  10  in a preferred embodiment because of its planar configuration and low profile. See  FIGS. 7A and 7B . 
     It is intended that the electrical control circuit have sensory capabilities to detect certain physical conditions of the device  10 , and to utilize the conditions to control operation of the motor  36 , and other appropriate functions of the control circuit  40 . These ancillary sensory circuits include: a moisture sensor  84  and circuit, for detecting the presence of moisture proximate the outlet port  20  of the desiccant cartridge  14 ; at least one vacuum pressure sensor  76  and circuit, for detecting a vacuum pressure in the interior chamber or elsewhere in the device; and a pressure differential sensor circuit, for sensing a difference in pressure between two sections of the gas/liquid flow pathway of the device  10 , e.g., between the inlet and outlet ports  18  &amp;  20  of the desiccator cartridge  14 . The sensors are interconnected to the control circuit  40  via electrical leads  44 . Sensors appropriate for accomplishing the various sensory functions of an electrical control circuit are known in the art and are readily adaptable for practice in the present invention by the ordinary skilled artisan. For example, a vacuum pressure sensor  76  (MPL model 500, diaphragm-type pressure differential sensor) suitable for practice in the present device is commercially available from Micro Pneumatic Logic, Inc. (Florida) from a line of pressure sensors. Other types of sensors are adaptable for use in the present invention for detecting or sensing pressure, such as surface strain gauges mounted on the surface of the desiccator cartridge  14 , and optical displacement gauges mounted to transmit light through the surfaces of desiccator cartridge  14 . For example, an optical fiber strain gauge  77  is commercially available from FISO Technologies (Quebec, model FOS “C” or “N”) from a line of optical strain gauges. This sensor can be used to monitor and indicate the presence of a vacuum in the desiccator cartridge by displacement (bending) of the cartridge surface under the force of a vacuum in the interior chamber  16 . Optical displacement/strain gauges  78  are also commercially, including for the detection of fluid intrusion into a section of tubing. These gauges typically comprise a combination light source/detector  78 a and a mirror  78 b. Distortion of the surface of the desiccator cartridge  14  on which the mirror  78 b is mounted alters the reflection path of the emitted light as it passes through the cartridge to return to the detector, which alteration is detectable. Of course, this requires the walls of the cartridge  14  proximate the optical displacement gauge  78  to be transparent to the light. The use of more than one pressure sensor  76  can allow sensing and/or measurement of the pressure differential between two different points in the gas/liquid flow pathway, such as between the inlet and outlet ports  18  &amp;  20  of the desiccator cartridge  14 . 
     The vacuum pressure sensor  76  is used to monitor the vacuum pressure in the interior chamber  16  of the desiccator cartridge  14 . When the vacuum pressure detected in the chamber  16  by the pressure sensor  76  is sufficient, the electric control circuit  40  may switch off the motor  36 , thereby conserving electrical power. When the vacuum pressure detected in the chamber  16  by the pressure sensor  76  is no longer sufficient the control circuit  40  may switch on the motor  36  to reestablish an appropriate vacuum pressure in the interior chamber  16  of the desiccator cartridge  14 . Also, the electrical control circuit  40  can include a clock/timer circuit for intermittently operating the electric motive means  36 , as another way of conserving electrical power. The I/O unit  70  can be utilized to set the time interval for the control circuit&#39;s intermittent operation of the motor  36 . 
     In an alternative preferred embodiment of the vacuum desiccator  10 , the battery  60  of the power source  46  is integral with the desiccator cartridge  14 a. As exemplified in  FIG. 8 , the battery  60  is contained in a battery compartment  110 , which is integral to the structure of the desiccator cartridge  14 a. Battery leads  112  connect the battery  60  to electrical battery contacts  114  on the exterior surface  120  of the desiccator cartridge  14 a. In this embodiment, the desiccator cartridge  14 a and battery  60  are replaceable as a unit. 
       FIG. 8  also illustrates another preferred feature of a desiccator cartridge  14 , in which a gas flow channel is disposed inside the interior chamber  16  of the cartridge  14 a. In the embodiment illustrated, the flow channel  120  is a tube connected to the outlet port  20  and having a length sufficient to allow it to be coiled or snaked about the interior chamber  16  (also see  FIG. 9B ). The flow channel tube  120  has perforations  122  along its length, or is otherwise constructed, to allow gas flow from the interior chamber  16  into the lumen of the flow channel tube  120  under the force of the vacuum pressure from the pump member  22 . Further shown in  FIG. 8 , is trapping agent  54 c having a pillow-like structure. The flow channel tube  120  is laid out on one side of the pillow trapping agent  54 c. In the preferred embodiment, the pillow trapping agent  54 c was constructed using 10 grams of sodium polyacrylate distributed between two layers of an elastic mesh material (nylon stocking). In addition to elastic mesh material, other fabrics are suitable for practice with the moisture trapping pillow  54 c, including knitted fabric mesh materials like gauze and similar fabrics. To maintain even distribution of the sodium polyacrylate, the two layers of elastic mesh material were sewn together to form compartments. The volume of the interior chamber  16  of the desiccator cartridge  14  was sufficient to hold the pillow and about 50 cc of trapped moisture. 
     A flow channel may be accomplished by means other than a tube. For example, a flow channel may be integrated into the desiccator cartridge  14  and be in gas flow communication with the interior chamber  16 . This embodiment of a desiccator cartridge  14  can be accomplished as shown in  FIGS. 9A and 9B , wherein the cartridge  14 b has a cover member  124  and a body member  126  ( FIG. 9A ). The cartridge cover member  124  has a gas flow channel  120 a integrated into it. The integral flow channel  120 a has perforations  122 a along its length, or is otherwise constructed, to allow gas flow from the interior chamber into the lumen of the integral channel  120 a under the force of the vacuum pressure from the pump member  22 . 
     While the above description contains many specifics, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of one or another preferred embodiment thereof. Many other variations are possible, which would be obvious to one skilled in the art. Accordingly, the scope of the invention should be determined by the scope of the appended claims and their equivalents, and not just by the embodiments.

Technology Classification (CPC): 0