Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2001-07-24
2003-05-06
Pham, Toan (Department: 3751)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S573100, C604S361000
Reexamination Certificate
active
06559772
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to moisture sensing devices and more particularly to an apparatus for sensing urination in clothing articles such as diapers worn by young children and/or incontinent adults, respectively, and for emitting alarm signal(s) to alert a caregiver that a diaper change is needed.
2. Prior Art
Bladder incontinence is a problem endemic in the very young and is cured only by intensive training as the young child goes through its second and third year of life requiring in the meantime the constant use of diapers. The same problem can affect the elderly or the infirm or persons of any age who may have this problem because of physiological or psychological problems. A problem of this nature may be a major source of embarrassment. The mere fear of such incontinence can be a danger to the psychological welfare of persons already subject to severe psychological pressures due to other infirmities. Such people, both the very young and the infirm often have no warning that their undergarments are being wet by urine until the undergarments are uncomfortably wet. There has always been a need for a device which can automatically warn either the person involved, or his/her caretaker (nurse or parent) that such undesirable leakage or wetness has occurred.
Various devices for detecting moisture or wetness such as caused by urination are known in the prior art. In diapers, the purpose of such devices is to set off an alarm when the diaper becomes wet. This permits a parent or other attendant to immediately tend to a newborn infant, toddler or an incontinent adult. Such devices usually include a pair of electrodes placed in the diaper which conduct electric current if wetness is detected. Prior art devices of this type, however, have numerous disadvantages such as requiring current-carrying conductors to pass mechanically through the diaper's plastic outer sheath, may subject the skin of the child/incontinent adult to potentially high voltages, may be sensitive only in a limited area in the diaper, may accidentally respond to the wearer sitting on a wet or metal bench or park slide or may have other undesirable drawbacks.
Urine is a solution of among other things, electrolytes, and will conduct a current of electricity. However, there are serious dangers involved in the use of electrical devices which use this property to sound an alarm. Fail-safe circuitry is a positive must, or there is serious danger of bodily harm.
In the past several years, portable devices have been proposed which have an electrode-containing pad disposed in the groin area of a user. A conductive path is established between the electrodes upon urination and an alarm of some kind is activated. These devices usually respond to urination in a relatively long interval of time (5-15 minutes) and are to a large extent impractical nowadays due to the advent of diapers filled with superabsorbent fill materials derived from a family of hydrophilic polymers known as polyacrylates. The simplest of these substances is sodium polyacrylate which can hold 800 times its weight in distilled water. Urine contains not only water but also dissolved salts and ions which reduce the absorbency of these materials only by a factor of 10. Some leading brands of diapers use combinations of polyacrylates that can absorb up to 1500 times their weight in water. The competition that these superabsorbent materials present to known moisture detecting devices is enormous. There seems to be insufficient pooling of urine in the diaper which constantly interferes with the operation of these devices.
Known moisture detecting devices also suffer from a number of disadvantages. For example, some devices have been less than completely acceptable to many children because of the bulkiness of the devices in the groin area. Also, some prior devices employ a long and rather stiff electrical cord coupled between a urine sensing pad in the groin area and an alarm unit on the wrist or shoulder of the user. Another disadvantage of such devices is the use of a relatively small urine sensor in the user's groin area. Such relatively small sensors are frequently missed by the flow of urine and fail to trigger the alarm.
A known moisture detecting device attempted to solve the superabsorbent diaper fill problem by using a capillary strip placed in the crotch area of the diaper and a pair of integrated electrical wires (electrodes) placed at the waistline of the diaper and connected to a portable electronic alarm unit. However, placing the electrodes so far away from the crotch area of the diaper resulted in a rather long alarm unit response time (up to 10 minutes). Specifically, device response was dependent on the amount and duration of urination since the liquid transfer distance from the tip of the capillary strip in the crotch area of the diaper to the electrodes at the waistline of the diaper was too long—it extended along the entire width of the diaper.
Therefore, the need arises for an improved device for sensing moisture from urination in an undergarment such as a diaper which can quickly and efficiently sense any available amount of urine present in the diaper crotch area regardless of the duration and amount of urination and which can trigger an associated alarm unit not in a matter of minutes but in a matter of a few seconds.
SUMMARY OF THE INVENTION
The present invention is directed to an apparatus for sensing moisture at a first location which comprises a strip of material adapted to efficiently absorb and transfer moisture via capillary attraction from the first location to a second location disposed in close proximity to the first location, and means for quickly sensing transferred moisture at the second location and triggering a corresponding alarm signal.
In accordance with one aspect of the present invention, the strip of material is made of a highly efficient capillary liquid transfer wick material.
In accordance with another aspect of the present invention, the wick strip comprises a substantially short first portion disposed at the first location, a substantially long second portion disposed adjacent the substantially short first portion and a third portion disposed adjacent the second portion.
In accordance with still another aspect of the present invention, the quick moisture sensing means includes at least two spaced apart conductive ink bands screen-printed on a first side of the second and third portions of the wick strip, a waterproof pouch for enclosing the second portion, and an alarm signaling circuit operatively coupled to the conductive ink bands on the third portion. The waterproof pouch comprises an opening at a first end and a pocket at a second end for removably receiving a portable alarm unit containing the alarm signaling circuit, the substantially short first portion of the wick strip protruding from the first end.
In accordance with yet another aspect of the present invention, the moisture sensing apparatus of the present invention further comprises means for increasing the moisture contact surface area at the second location. The moisture contact surface area increasing means includes a terminal tortuous conductive ink pattern screen-printed on the first side of the second portion in close proximity to the substantially short first portion.
In accordance with a further aspect of the present invention, the waterproof pouch is adapted for coupling to a clothing article on which the first location is defined.
In accordance with an alternative aspect of the present invention, the wick strip comprises a substantially short first portion disposed at the first location, a second portion disposed adjacent the substantially short first portion and a substantially long third portion disposed adjacent the second portion.
In accordance with another alternative aspect of the present invention, the quick moisture sensing means includes at least two spaced apart conductive ink bands screen-printed on a first side of the substantially long third portion of
Evans Robert E.
Haussler Warren M.
Zand Farnaz
Fulbright & Jaworski L.L.P.
Pham Toan
Zand Farnaz
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