Abstract: A support apparatus includes a force sensing array positioned thereon that includes multiple layers of material that are arranged to define an elastically stretchable sensing sheet. The sensing sheet may be placed underneath a patient to detect interface forces or pressures between the patient and the support structure that the patient is positioned on. The force sensing array includes a plurality of force sensors. The force sensors are defined where a row conductor and a column conductor approach each other on opposite sides of a force sensing material, such as a piezoresistive material. In order to reduce electrical cross talk between the plurality of sensors, a semiconductive material is included adjacent the force sensing material to create a PN junction with the force sensing material. This PN junction acts as a diode, limiting current flow to essentially one direction, which, in turn, reduces cross talk between the multiple sensors.

Abstract: A flexible force or pressure sensing mat includes a first sheet of electrically conductive first paths, a second sheet of electrically conductive second paths, and a sensing layer positioned between the first and second sheets. The first and second conductive paths are oriented transversely to each other, and the locations of their intersections define individual sensing areas or sensors. The sensing layer is made from materials that have first and second electrical characteristics—such as capacitance and resistance—that vary in response to physical forces exerted thereon. A controller repetitively measures the multiple electrical characteristics of each sensor in order to produce a near real time pressure distribution map of the forces sensed by the mat. The mat can be used on a patient support surface—such as a bed, cot, stretcher, recliner, operating table, etc.—to monitor and help reduce the likelihood of a patient developing pressure ulcers.

Abstract: A pressure sensing sheet includes at least first, second, and third layers wherein the first and third layers each have conductive paths defined therein that are separated by nonconductive spacers. The orientation of the conductive paths of the first layer are transverse to the orientation of the conductive paths of the third layer. The second layer is made of material that has an electrical characteristic that changes with applied pressure, such as, but not limited to, piezoresistive or piezoelectric material. The first and/or third layers are made from multi-material sheets wherein a first type of material will repel conductive particles when subjected to an autocatalytic coating process, while the second type of material will bond with the conductive particles during the autocatalytic coating process. The use of different materials in the first and/or third layers facilitates the manufacturing of the conductive paths and nonconductive spacers.

Abstract: Flexible force/pressure sensors for producing electrical output signals proportional to forces or pressures exerted on the sensor include a thin, elastically deformable foam pad laminated between a pair of electrically conducive fabric sheets. A piezocapacitive embodiment of the sensor utilizes an elastically deformable perforated open-cell polyurethane foam pad preferably saturated with glycerin to increase the capacitance of the sensor. The piezocapacitive sensor section is preferably stacked onto a piezoresistive section having a second open-cell foam pad containing piezoresistive carbon particles to form a hybrid piezocapacitive/piezoresistive sensor. A third, “leaky dielectric” embodiment of a sensor includes a single open-cell foam pad which contains both a dielectric liquid and conductive particles. A low frequency such as d.c.

Abstract: A support apparatus includes a force sensing array positioned thereon that includes multiple layers of material that are arranged to define an elastically stretchable sensing sheet. The sensing sheet may be placed underneath a patient to detect interface forces or pressures between the patient and the support structure that the patient is positioned on. The force sensing array includes a plurality of force sensors. The force sensors are defined where a row conductor and a column conductor approach each other on opposite sides of a force sensing material, such as a piezoresistive material. In order to reduce electrical cross talk between the plurality of sensors, a semiconductive material is included adjacent the force sensing material to create a PN junction with the force sensing material. This PN junction acts as a diode, limiting current flow to essentially one direction, which, in turn, reduces cross talk between the multiple sensors.

Abstract: An adaptive cushion for reducing pressure on body parts of a person positioned on a chair or bed includes an overlay cushion having a plurality of individual air bladder cells, each having thereon a force sensor. The cushion includes a controller for inflating and deflating individual air bladder cells to air pressures that tend to reduce the interface pressures sensed by the force sensors. A pressure reduction method includes varying the inflation pressure in a first air bladder cell while measuring the sum of the interface pressures exerted on all or a plurality of the air bladder cells, re-pressurizing the first cell to that air pressure for which a minimum total interface pressure was obtained, repeating this process for the remaining air bladder cells.

Abstract: A force sensing array includes multiple layers of material that are arranged to define an elastically stretchable sensing sheet. The sensing sheet may be placed underneath a patient to detect interface forces or pressures between the patient and the support structure that the patient is positioned on. The force sensing array includes a plurality of force sensors. The force sensors are defined where a row conductor and a column conductor approach each other on opposite sides of a force sensing material, such as a piezoresistive material. In order to reduce electrical cross talk between the plurality of sensors, a semiconductive material is included adjacent the force sensing material to create a PN junction with the force sensing material. This PN junction acts as a diode, limiting current flow to essentially one direction, which, in turn, reduces cross talk between the multiple sensors.

Abstract: A flexible force or pressure sensing mat includes a first sheet of electrically conductive first paths, a second sheet of electrically conductive second paths, and a sensing layer positioned between the first and second sheets. The first and second conductive paths are oriented transversely to each other, and the locations of their intersections define individual sensing areas or sensors. The sensing layer is made from materials that have first and second electrical characteristics—such as capacitance and resistance—that vary in response to physical forces exerted thereon. A controller repetitively measures the multiple electrical characteristics of each sensor in order to produce a near real time pressure distribution map of the forces sensed by the mat. The mat can be used on a patient support surface—such as a bed, cot, stretcher, recliner, operating table, etc.—to monitor and help reduce the likelihood of a patient developing pressure ulcers.

Abstract: Flexible force/pressure sensors for producing electrical output signals proportional to forces or pressures exerted on the sensor include a thin, elastically deformable foam pad laminated between a pair of electrically conducive fabric sheets. A piezocapacitive embodiment of the sensor utilizes an elastically deformable perforated open-cell polyurethane foam pad preferably saturated with glycerin to increase the capacitance of the sensor. The piezocapacitive sensor section is preferably stacked onto a piezoresistive section having a second open-cell foam pad containing piezoresistive carbon particles to form a hybrid piezocapacitive/piezoresistive sensor. A third, “leaky dielectric” embodiment of a sensor includes a single open-cell foam pad which contains both a dielectric liquid and conductive particles. A low frequency such as d.c.

Abstract: Force or pressure transducer arrays have elastically stretchable electrically conductive polymer threads disposed in parallel rows and columns that contact at intersections thereof a piezoresistive material which has an electrical resistivity which varies inversely with pressure or force exerted thereon to form a matrix array of force or pressure sensor elements. The threads are fixed to a single one or pair of flexible elastically stretchable substrate sheets made of thin sheets of an insulating polymer such as PVC, or for greater elasticity and conformability to irregularly-shaped objects such as human body parts, an elastically stretchable fabric such as LYCRA or SPANDEX. Elastic stretchability of the sensor arrays is optionally enhanced by disposing either or both row and column conductive threads in sinuously curved, serpentine paths rather than straight lines.

Abstract: An adaptive cushion for reducing pressure on body parts of a person positioned on a chair or bed includes an overlay cushion having a plurality of individual air bladder cells, each having thereon a force sensor. The cushion includes a controller for inflating and deflating individual air bladder cells to air pressures that tend to reduce the interface pressures sensed by the force sensors. A pressure reduction method includes varying the inflation pressure in a first air bladder cell while measuring the sum of the interface pressures exerted on all or a plurality of the air bladder cells, re-pressurizing the first cell to that air pressure for which a minimum total interface pressure was obtained, repeating this process for the remaining air bladder cells.

Abstract: An adaptive cushion apparatus for minimizing force concentrations on body parts of a person seated or lying on a chair or bed includes an overlay cushion having a plurality of individual air bladder cells, each having thereon a stretchable piezoresistive force sensor of novel design and construction. The apparatus includes an electro-pneumatic control system for inflating and deflating individual air bladder cells to pressures measured by a pressure transducer which tend to minimize force concentrations sensed by the force sensors.

Abstract: Force or pressure transducer arrays have elastically stretchable electrically conductive polymer threads disposed in parallel rows and columns that contact at intersections thereof a piezoresistive material which has an electrical resistivity which varies inversely with pressure or force exerted thereon to form a matrix array of force or pressure sensor elements. The threads are fixed to a single one or pair of flexible elastically stretchable substrate sheets made of thin sheets of an insulating polymer such as PVC, or for greater elasticity and conformability to irregularly-shaped objects such as human body parts, an elastically stretchable fabric such as LYCRA or SPANDEX. Elastic stretchability of the sensor arrays is optionally enhanced by disposing either or both row and column conductive threads in sinuously curved, serpentine paths rather than straight lines.

Abstract: Force or pressure transducer arrays have elastically stretchable electrically conductive polymer threads disposed in parallel rows and columns that contact at intersections thereof a piezoresistive material which has an electrical resistivity which varies inversely with pressure or force exerted thereon to form a matrix array of force or pressure sensor elements. The threads are fixed to a single one or pair of flexible elastically stretchable substrate sheets made of thin sheets of an insulating polymer such as PVC, or for greater elasticity and conformability to irregularly-shaped objects such as human body parts, an elastically stretchable fabric such as LYCRA or SPANDEX. Elastic stretchability of the sensor arrays is optionally enhanced by disposing either or both row and column conductive threads in sinuously curved, serpentine paths rather than straight lines.

Abstract: An anti-slosh device for attenuating oscillations of liquids in tanks caused by movement of vehicles in which the tank is located comprises an elongated flat, rectangularly, shaped, uniform thickness strip of a liquid impervious material such as polyethylene or polycarbonate which is formed into a string of arcuately curved loops. One embodiment of the device has located at opposite ends thereof spirally-shaped, quasi-helical end loops which form a figure-8 shape, and a center loop disposed obliquely between the end loops. A two-loop version of the device has two end loops but no center loop. The anti-slosh device is used to reduce the duration of undesirable oscillations induced in a liquid in a tank by placing a plurality of the devices in the interior of a tank, as by inserting a plurality of the devices through a fill tube or other access port of the tank.

Abstract: A patient support surface comprises a cover defining an interior region, a modifiable support layer situated in the interior region and having at least one air bladder, and a sensor layer situated in the interior region and having at least one sensor configured to detect a physiological parameter of a patient atop the patient support surface.

Abstract: A normal force gradient/shear force sensor device and measurement method for measuring internal stresses in tissues of a person supported by a chair or bed includes a planar matrix array of peripheral normal force sensors radially spaced from central shear force sensors, comprising an electrically conductive disk located within a circular opening bordered by circumferentially spaced apart electrodes. The disk and electrodes are located between upper and lower cover sheets made of a stretchable material such as polyurethane; one cover sheet is adhered to the disk and the other sheet is adhered to a support sheet for the electrodes. Motion between the cover sheets in response to shear forces exerted on the array causes the disk to press more or less tightly against the electrodes varying electrical conductance between the disk and electrodes proportionally to the magnitude and direction of the shear force.

Abstract: A portable, hand-holdable Blanching Response Tester apparatus (BRT) pressable against the skin of a human patient to provide an indication of a non-blanchable erythema indicative of an incipient pressure sore includes a housing having in a front end wall thereof an optically transmissive window and within the housing a broad-band light source electrically energizable to emit light including energy in the near infrared (0.8? to 1.5?) outwards through the window. A first, leading photodetector spaced laterally apart from the light source and a second, trailing photodetector spaced equidistant from the light source in an opposite direction have fields of view which include regions of the skin ahead of an behind a central area of the skin illuminated by the light source.

Abstract: A portable, hand-holdable Blanching Response Tester apparatus (BRT) pressable against the skin of a human patient to provide an indication of a non-blanchable erythema indicative of an incipient pressure sore includes a housing having in a front end wall thereof an optically transmissive window and within the housing a broad-band light source electrically energizable to emit light including energy in the near infrared (0.8&mgr; to 1.5&mgr;) outwards through the window. A first, leading photodetector spaced laterally apart from the light source and a second, trailing photodetector spaced equidistant from the light source in an opposite direction have fields of view which include regions of the skin ahead of an behind a central area of the skin illuminated by the light source.

Abstract: A transducer sensor array for measuring forces or pressures exerted on a surface includes a lattice of individual force or pressure sensor transducer elements comprising intersecting regions of pairs of elongated, flexible threads, each consisting of a central electrically conductive wire core covered by a layer of piezoresistive material having an electrical resistivity which varies inversely with pressure exerted on the material. The threads are arranged into two parallel planar sets, one set forming parallel spaced apart rows and the other set forming parallel spaced apart columns angled with respect to the rows. Row and column piezoresistive threads are retained in physical contact with one another at cross-over intersection points forming a lattice of piezoresistive junctions comprising individual force sensing elements, either by being bonded between a pair of thin, flexible, upper and lower laminating sheets, or by being interwoven to form a fabric mesh.