Filter with varying density which is responsive to fluid flow

Details Filter with varying density which is responsive to fluid flow Filter with varying density which is responsive to fluid flow

1999-02-08

2001-04-17

Seidel, Richard K. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C210S263000, C210S264000

Reexamination Certificate

active

06217545

ABSTRACT:

The present invention relates to a filter and its use in conjunction with a tubular conduit. The filter is specifically constructed to fit within a conduit in such a manner that enables it to move in response to flow of liquid under certain conditions. According to the invention, the filter is constructed to have at least two distinct regions, a central core region having a more dense construction and an outer peripheral region having a less dense construction. A filter constructed in such a manner and to predetermined dimensions which compliment the dimensions of a conduit, may be seated within the conduit under relatively static conditions but may travel within the conduit in response to flow of liquid through the conduit. The filter is constructed so that frictional forces maintain the filter in place when it is under static conditions and when it is subject to forces from the flow of air necessary to draw liquid up through the conduit. In the preferred embodiment of the invention, these forces are analogous to the conditions created by an individual drawing air through a filter seated within a conventional drinking straw. The filter is constructed to allow for the passage of air through the conduit with an insignificant pressure drop across the filter. When liquid traveling through the conduit comes in contact with the filter, the force of the liquid on the filter overcomes the frictional forces holding the filter in place within the conduit and causes the filter to move.
In a preferred and contemplated embodiment, the device as described above is used in conjunction with a medication delivery system for oral ingestion.
BACKGROUND OF THE INVENTION
Filters are routinely used within conduits for filtration and their use in such applications is both well known and widespread. In most applications filters are designed to be securely seated against the forces of fluid flow. In connection with prior art directed to the provision of oral medications, it is known to use filters as a substrate to support medication within a conduit such as a drinking straw. Such devices typically contain a single dose of medication which, in some circumstances, is supported by either a screen or a porous material which is wedged between the sidewalls of the straw. Some devices may provide a separate support structure to maintain the screen or filter in place. The prior art also discloses the use of solid impediments which will move within a conduit in response to fluid flow in connection with other applications. Such solid impediments typically have a diameter less than the diameter of the conduit and thus are not designed to frictionally engage the conduit or to be retained in a stationary position. One application where such solid impediments are used is in connection with the regulation and or metering of fluid flow.
In connection with the provision of oral medications, straws are frequently used to administer a single dose of a drug. In such devices, fluid enters the straw, passes through the filter, then puts the drug into suspension or solution, and next exits the opposite end of the straw. It is desirable to provide a substrate which would support the drug and allow the patient to draw liquid through the straw and, enable the substrate to move a predetermined distance depending on the volume of fluid which passed through the straw. The movement of the substrate in the device in response to fluid flow would provide a visual indication as to whether a predetermined amount of fluid had passed through the straw and consequently was ingested by a patient. Accordingly, it is one object of the invention to provide a substrate which will both support medication within a straw, allow for the administration of the medication and further allow the substrate to move in response to the flow of fluid. It is a further object of the present invention to provide a material within a conduit which will remain seated within the conduit in response to fluctuations in air pressure, however move in response to fluid flow under conditions analogous to those created and typically encountered using a drinking straw. A further object of the invention is to provide a substrate which allows air to freely travel through an impediment and thus exhibit no response to air flow however, when liquid is allowed to contact the impediment, the impediment may move in response to the flow. A further object of the present invention is to provide a device which provides an indication of whether a predetermined amount of fluid has passed through a conduit. Yet a further object of the invention is to provide a device to assist in the oral delivery of solid medication which provides an indication of whether or not a predetermined amount of fluid has passed through the liquid and thereby provide an indication as to whether or not medication has been ingested. A further object of the invention is to provide a device which is appealing and which provides encouragement to children by providing a positive indication that a medication has passed through a conduit.
SUMMARY OF THE INVENTION
According to the invention, a filter is constructed from synthetic fibers and provided within a conduit. Both the filter and conduit are manufactured to precise specifications in order to meet certain performance criteria relating to the movement of the filter under preselected operating conditions. In order to construct the filter which will meet the desired performance criteria in a reproducible manner, the various operating parameters are first identified including the dimensions of the conduit and expected forces acting upon the filter. For example, the expected pressure differentials applied to conduits in order to initiate and maintain flow of fluid through the conduit are determined.
In the preferred embodiment, a filter is provided which will remain stationary within the conduit until it is subjected to forces from the flow of liquid. In this embodiment, the filter remains stationary within the conduit as air is drawn through the conduit to cause fluid to rise up into and flow through an opening of the conduit. When the flow of fluid comes into contact with the filter, the force imposed by the fluid will dislodge the filter and allow it to move along the tubular passage. The filter impediment is designed to travel from the upstream end of the conduit, along the distance of the conduit until it is impeded by a constriction provided within the conduit at the downstream end. Upon the interruption of fluid flow, the filter impediment is retained in a stationary position at the opposite, downstream end of the conduit.
In a preferred embodiment the conduit is similar to a conventional drinking straw having a uniform inner diameter oriented in a substantially vertical position however the ends are modified to prevent the filter from passing out of the straw. The flow of fluid through the straw is accomplished by a person sucking on the downstream end of the straw, located at the upright end. It is contemplated that flow through a conduit could be effected in alternative manners which subject the filter contained therein to analogous forces and, both the movement of the filter and the performance of the device would be substantially similar. For example, in a further contemplated embodiment, flow through the conduit is initiated by drawing back a plunger creating a vacuum in the conduit, such as accomplished using a conventional syringe. In another contemplated embodiment, the conduit is an overflow channel and flow is initiated by gravity. In yet a further contemplated embodiment, a conduit is in communication with a flexible reservoir and flow of the fluid is initiated by compression of the reservoir.
In the preferred embodiment, upon application of suction by an individual to the top of the straw, the filter impediment will rapidly travel up the straw until further upward movement is physically impeded by a constriction in the straw. The desired performance characteristics are achieved and optimized by creating a filter having variable densities, wherei

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