Patent Application
20200246500
The invention relates to a water-soluble conductor embedded in personal hygiene absorbent articles of the type worn in the crotch region of a wearer to absorb body excreta (diapers). The water-soluble conductor is used to detect soiled incontinent hygiene articles with changing conductor resistance due to conductor dissolving and dispersing while in contact with excreta.
Diapers are typically fabricated with an absorbent core between a topsheet on the wearer-facing side and the liquid impermeable backsheet on the garment-facing side of the diaper. As the absorbent core becomes saturated with urine, it tends to sag down in the crotch region of the wearer due to the weight of the fluid. This may cause loss of contact of the article along the thighs of the wearer and increase the possibility of leakages. While elastic waist bands and other elasticized parts such as barrier leg cuffs are commonly used to maintain contact and fit, these solutions are limited and leakage can still occur, especially if the diaper was not put in place correctly or was displaced out of position by the wearer.
Caregivers monitoring diapered individuals use sight, smell and touch to determine if the diaper is wet without any indication of the degree of wetness or how long the individual has been wet. A visual wetness indicator fabricated by printing or otherwise fabricating a chemical stripe on the center of the backsheet along the length of the diaper, changes color when in contact with urine. Even though the stripe is the length of the diaper, only the portion in contact with the excreta changes color which my not be visible to the caregiver.
There are electronic diaper wetness monitors with a moisture sensor on the back sheet such as parallel carbon stripes where the resistance between the stripes decreases as a function of the length of the stripes in contact with the urine. The excreta must penetrate the absorbent core and provide a bridge between the carbon stripes to be recognized or sensed as a wet diaper.
These backsheet sensors signal a wet diaper when the absorbent core is saturated and excreta is covering a significant portion of the sensor. And in particular, sensors relying on a change in resistance have an additional sensing problem with the urine varying in conductivity by as much as 5X. The wide variance in conductivity, and thus resistance, requires a greater length of the carbon stripes to be covered with urine in order to indicate the diaper is wet. There is a high probability the excreta will escape the diaper and soil bedding and/or cloths well before the system is signaling a wet diaper.
Another type electronic sensor uses Frequency Identification (RFID) tags placed between the topsheet and wearer to detect a wet diaper such as found in U.S. Pat. No. 10,069,205. The RFID tag antenna changes resonant frequency when setting on wet substrate as compared to a dry substrate. The RFID reader identifies the change in frequency signaling a wet diaper.
The RFID sensor on the topsheet is sensitive to stress incontinence due to weak pelvic and sphincter muscles allowing leakage during laughing, sneezing, coughing as a few examples of stress incontinence signaling a false wet diaper to the caregiver causing a premature diaper change. RFID requires a hand held reader that needs to be within two feet or less from the RFID tag in order to read the signal (active the tag for transmitting status), not a significant advantage compared to the chemical sensor changing color.
The Applicants' invention is a water soluble conductor when connected to an electronic monitoring circuit to detect the changes in the water soluble conductor minimizes the probability of leakage as well as unexpectedly sending a false signal prior to full utilization of the diaper.
A first aspect, the invention has a Water Soluble Conductor (WSC) deposited on a non-woven fabric for incorporating in the manufacturing of wetness sensored diapers. WSC means any flexible material composition of conducting elements or components like silver, gold, carbon black, carbon nanotubes, or graphene that conducts electric current or any combination thereof, mixed with a water soluble component such as polyvinyl alcohol copolymers, polyethyloxyazoline, polyvinyl pyrrolidone, polyvinyl alcohol, polyacrylamide, polyglycols or polyacrylic acid or any mixtures thereof. The WSC in instances includes a thickness agent, surface active agent and/or fast dry agent for a flexible, conductor that disperses when wet creating open or very high resistance circuit.
An electronic monitor attached to the water-soluble conductor (WSC) to monitor the WSC for a change in resistance determining the fabricated sensored diaper has been soiled. Monitor means any electronic circuit with power to pass current through the WSC and monitor changes in conductivity of the WSC and signal a caregiver visually illuminating or flashing a LED for a wet or soiled incontinent garment or, use a device capable of signaling a caregiver with a RF data transmission containing the status of the incontinent garment, wet or dry.
The invention is a solution for managing incontinence with electronic wetness monitor to provide caregivers notice of a soiled incontinent garment or pad and avoid leakage resulting in soiled clothing and/or furniture items such as chairs and beds. Invention enables caregivers to quickly remove the soiled diaper minimizing the potential for rash and eventual urinary track infection associate with prolonged periods of time in a soiled diaper.
The invention is a novel way to manufacture a moisture sensor combining water-soluble polymeric films with conductive fine particles where the water-soluble film disintegrates in water (urine and/or feces) dispersing the conductive particles. Urine and/or feces disintegrates the conductive polymeric film disrupting or eliminating conductivity in the portion of the film that lays bare to urine and/or feces and the disruption is detected by an electronic sensor connected to the film. Disruption means an increase in resistivity. The water-soluble conductive polymer film-forming and printable composition mixes polyvinyl pyrrolidone, polyvinyl alcohol and aliphatic polyethers or polyethylene glycols or a combination thereof with conductive gold, silver, carbon black, graphene, or graphite or a combination thereof manufacturing a water soluble conductive material for fabricating moisture sensors.
Flexibility of the polymeric film is improved with a plasticizer 5% wt to 15% wt such as water-soluble polyglycols. Additionally, thickening agent such as sodium carboxymethylcellulose can be used to provide a viscosity of 2 poise to about 1500 poise for casting or printing the conductive polymer.
One embodiment depicted in
WSC is designed for a resistively per square of 20 ohms to 100 ohms and preferably 25 to 50 ohms per square at a thickness of 40 microns to 80 microns. WSC must be flexible to accommodate the wearer's movement in and with the incontinent garment. Plasticizers are added to the dimethylformamide, dimethylacetamide, ethylene glycol, propylene glycol and water-soluble polyglycols. Plasticizers improve the flexibility and resistance to cracking or flexing of the mixed polymer films of this invention. Flexible means twisting and folding without changing the resistance per square of the dry WSC sensor 100.
One fabrication of sensor 100, referred to as stamped water soluble conductor (SWSC), uses POVH carbon black film with width W1105 stamped or otherwise cutout with spacing S1104 and length L1106 centered on W1105 repeating every (L1106+W2107) length for 5000 meters or more.
A preferred embodiment of the invention is a liquid WSC that can be printed on liquid permeable fabric 502 using a low cost printing machine as depicted in
Urine is wicked from the top sheet 601 by the acquisition layer 602 past sensor layer 500a into absorption layer 605. Urine passing the WSC in the sensor 100, erodes the WSC stripes increasing the resistance, but does not disperse the carbon, which would create an open circuit. In one instance, the resistance between WSC contacts 503a and 504a was measured after 50 ml of synthetic urine was poured on the diaper in the crotch area, followed by additional 50 ml volume poured on the diaper while measuring resistance during and after each application of 50 ml of urine. The WSC opened after 1000 ml to 1500 ml of synthetic urine was poured on the crotch area of the diaper 700.
WSC sensor 100 can be used to monitor the time and volume of urine and feces in diapers 700 providing wearer's incontinent garment status to a caregiver. Relationship between excreta volume and WSC sensor 100 resistances is programmed into a monitor to provide the caregiver the time for various episodes of urination or bowel movement. Caregiver will have the information regarding the patient's incontinence to make decisions for the best health of the patient. Wetness not sufficient to trigger an alarm under normal circumstances would be detrimental to the patient if the wetness were prolonged in time. The WSC sensor 100 along with an attached monitor would allow or flag the caregiver to replace the soiled incontinent garment with a clean dry garment.
