CZ36859U1 - A pressure monitoring system and a wheelchair incorporating the system - Google Patents

Description

In the registration procedure, the Industrial Property Office does not determine whether the subject of the utility model meets the conditions of eligibility for protection according to § 1 of Act. E. 478/1992 Coll.

A pressure monitoring system and a wheelchair incorporating the system

Field of technology

The technical solution is focused on a system (i.e. a device) for monitoring the pressure, especially of the seating and support parts on the mat, for example for a wheelchair, office chair, car seat.

Current state of the art

In the current state of the art, a large number of different seat pads for wheelchairs are known. The classic design of the pads entails a number of disadvantages for the user, one of the most important disadvantages of which is the easy formation of skin problems and bruises due to staying in a certain position for a long time. For this reason, various seat pads have been developed that allow measuring the pressure exerted by the user on the pad over a certain period of time in order to prevent and speed up the treatment of pressure sores.

In recent years, seating pads with a capacitive sensor have been used the most, e.g. document US 5,775,332 A. These pads work on the principle of bringing two conductive surfaces closer together, between which there is a dielectric. The changing distance of these surfaces is measured, from which the applied pressure is subsequently calculated. This sensor is located in the seat pad. As patients in wheelchairs can often experience incontinence or any other spillage of liquid and moisture, the pad needs to be properly cleaned, which is often very difficult or impossible with these types of pads.

Another known type of pad uses a solid pad that is part of the cushion of the seat pad. In order for the measurement to be as accurate as possible, it is necessary to place the firm mat as close as possible to the seating surface. This can make the entire pillow too hard and uncomfortable for the user.

Monitoring mats are not yet sufficiently widespread among wheelchair users, despite their indisputable benefits, because their purchase price is too high for many users. In the current state of the art, you can find especially seat pads, but the risk of pressure sores also arises in many immobile patients on other parts of the body, e.g. back, forearms.

It would be advisable to come up with a solution for a universal pressure monitoring pad, which will be sufficiently durable and comfortable even for patients with a more severe degree of immobility, and at the same time enable its acquisition by as many patients as possible.

The essence of the technical solution

To some extent, the above shortcomings are eliminated by a system (i.e. a pressure monitoring device) for wheelchairs. This system includes a coating, a set of pressure sensors and a control unit. Pressure sensors are arranged in the coating along the surface of the coating in contact with the user. In the case where it is a cover intended for a seat pad, these pressure sensors are placed in the part of the cover on which the user sits. The pressure sensors are connected to the control unit, which processes the data from these pressure sensors and thus enables the evaluation of the pressure exerted by the user. The pressure sensors are removable from the coating, which allows simple cleaning of the coating, e.g. by washing in a washing machine.

This system (i.e. device) allows for easy cleaning of the coating, e.g. by washing, without degrading the pressure sensors. In the event of damage to the pressure sensors, the sensors are simply replaceable thanks to their removability. As the pressure sensors are part of the coating, between any padding or padding and the user, the measured pressure values are more accurate than

- 1 CZ 36859 U1 in the case when the pressure sensors are placed in the cushion under the filling. Since the pressure measurement system is part of the cover, the user can apply this cover to different pillows according to their own preferences, and when the pillow is worn, for example, the entire pad does not have to be disassembled or replaced, which can be expensive. In addition, the user can perform this exchange himself, he does not have to send the product to the manufacturer, for example.

Advantageously, a set of pressure sensors can be arranged in a sensor network. The sensors can then be regularly arranged in a grid, and the density of this grid defines the resolution of the pressure measurement. Some sensors, for example an entire row and/or column, may share a common wire. A sensor network can include two layers. Both layers include alternating strips of conductive material and non-conductive material - the conductive strips are interspersed with insulating strips. The layers are placed on top of each other with the conductive strips across, preferably with the strips laid perpendicular to the strips of the second layer. This creates a grid, making it possible to identify the location of the pressure change with precision given the width of the bars. The places where the conductive strips of the two layers overlap are equipped with a material that changes its electrical resistance depending on the pressure, so they form pressure sensors. The structure of the network allows for easier fixing in the coating, e.g. only two sides of the rectangular sensor network can be attached, and at the same time easier removal than in the case of e.g. point pressure sensors. Simply adding a sensor network to the coating can result in lower manufacturing costs (e.g. by reducing pad assembly time) than, for example, a capacitive sensor pad. The sensor network can advantageously be placed directly under the surface of the coating, which is in direct contact with the user, which, in addition to accurate measurement values, can also be convenient for the user, since the network is thin and flexible. The flexibility of the sensory network allows it to adapt to the seating areas of the wheelchair user and thereby preserve the functionality of the anti-decubitus cushion underneath.

The pressure sensors can be stored in a package removably stored in the coating, which facilitates the removal of the pressure sensors and at the same time the pressure sensors are better protected from damage.

Advantageously, the control unit can be fixed in the coating so that it can be easily removed from the coating before cleaning the coating and at the same time it would be better protected against damage or unwanted movement in the coating.

The system (i.e., device) may include a light source that may be controlled by a control unit. This light source can be turned on by the control unit when the pre-defined limit value of pressure is exceeded for a pre-defined time interval in order to warn the user in time and thus prevent crushing or other damage. Both the pressure limit value and the time interval can be preset in the control unit, but they are preferably adjustable by the user or his attending physician, for example remotely using their user device.

The system can further include a sound source that can be controlled by the control unit. This sound source can be triggered by the control unit when a pre-defined pressure threshold is exceeded for a pre-defined time interval to alert the user in time and prevent crushing or other damage.

The system may include a portable display device that is data-linked to the control unit and serves for graphical display of the measured output values of the control unit and control of the control unit. A portable display device can be selected from a set including a mobile phone, smart watch, tablet, laptop, etc. This portable device enables easier setting of important parameters in a more user-friendly way than if the setting were done directly on the control unit. At the same time, it enables a clearer display of measured and other additional values. At the same time, it enables these actions to be performed even if the user is not in direct contact with the mat, which is particularly advantageous for patients with mobility impairments.

For greater comfort of the user when in contact with the pad, the system (i.e. device) can include a coating filler, e.g. hollow fiber, ball filler, foam, batting, etc. The filler can be placed between

- 2 CZ 36859 U1 by the surface of the coating (parts not in contact with the user) and pressure sensors, i.e. so that the sensors are as close as possible to the user, especially so that they are not separated from him by a filler that would distort the pressure values.

Furthermore, the shortcomings of known solutions are removed to some extent by a wheelchair that includes a pressure monitoring system. Advantageously, this system can be a part of a wheelchair cushion or an anti-decubitus seat for a wheelchair, possibly a back rest, forearm rest and other possible supporting surfaces of a wheelchair. This will allow monitoring of more parts of the user's body where bruises or other damage could occur.

Clarification of drawings

The essence of the technical solution is further clarified on examples of its implementation, which are described using the attached drawings, where on:

Giant. 1 is a block diagram showing the connection of key elements and the transfer of data from pressure sensors to a portable device, on

Giant. 2 schematically shows the sensor network in the coating, its connection to the control unit and the possibility of sending data to a portable device, on

Giant. 3 schematically shows alternative point pressure sensors, their connection to the control unit and sending data to a portable device, on

Giant. 4 shows a drawing of a waterproof package for the control unit and power source, at

Giant. 5 shows a drawing of the internal arrangement of the package for the control unit and the source.

Examples of implementing a technical solution

The technical solution will be further explained on examples of implementation with reference to the relevant drawings. The first exemplary embodiment of the basic parts of the solution and its arrangement is shown in Fig. 1 and Fig. 2.

The subject of the presented solution is a system (i.e. a device) for pressure monitoring for wheelchairs. This system includes a coating 1, a set of pressure sensors 2 and a control unit 3. The pressure sensors 2 are embedded in the coating 1 along the surface of the coating 1 that is in contact with the user 4, preferably they are uniformly arranged along the width and length of this surface. In the case where it is a cover 1 intended for a seat pad, these pressure sensors 2 are located in that part of the cover 1 on which the user 4 sits, i.e. they are along the upper surface. The pressure sensors 2 are connected to the control unit 3, which processes the data from these pressure sensors 2 and thus enables the evaluation of the pressure exerted by the user 4. The pressure sensors 2 are removable from the coating 1, which enables simple cleaning of the coating 1, e.g. by washing in a washing machine.

An exemplary design and arrangement of pressure sensors 2 is shown in Fig. 1 and Fig. 2. A preferred set of pressure sensors 2 is a sensor network 5. The sensor network 5 includes two layers. Both layers include alternating strips of conductive material and non-conductive material - the conductive strips 6 are interspersed with insulating strips 7, preferably with a spacing of 5 to 15 mm, e.g. 10 mm. The layers are placed on top of each other with conductive strips 6 across, preferably with the strips laid perpendicular to the strips of the second layer. This creates a grid, making it possible to identify the location of the pressure change with precision given the width of the bars. The places where the conductive strips 6 of both layers overlap are provided with a material that changes its electrical resistance depending on the pressure, so that they form pressure sensors 2. In the case of using a sensor network 5, each conductive strip 6 is preferably connected to an analog multiplexer 11, which is further connected to the control unit 3. Analogue

- 3 CZ 36859 U1 multiplexer 11 can be powered by an external source 12, the same as the control unit 3 (see Fig. 1). Alternatively, if the source 12 will be part of the control unit 3, the analog multiplexer 11 can be powered directly by the control unit 3.

The embodiment with the analog multiplexer 11 can be as shown in Fig. 2, where, for example, the transverse conductive strips 6 in one layer are connected to the positive pole of the analog multiplexer 11, the longitudinal conductive strips 6 of the second layer to the negative pole. This makes it possible for each pair of intersecting conductive strips 6, for example by applying voltage, to measure the current passing between these strips, and thus also the resistance between them, which the control unit 3 can convert into pressure with regard to the material used and the dependence of its resistance on pressure. When the system is switched on, for example, when sitting on the mat, the layers are compressed - the places where the conductive strips 6 are covered are compressed, which closes the electrical circuit. Depending on the force of compression of the individual overlap points, the electric current that is measured changes. This current preferably passes through the analog multiplexer 11 to the control unit 3, which recalculates these changes in electric current using a predefined pressure formula.

It is advantageous to use for the conductive strips 6 a fabric made of a wire made of a conductive material, for example silver or copper, which will be covered with a material, for example a textile, changing its resistance properties depending on the applied pressure. For the insulating strips 7, it is advantageous to use an insulated wire, for example lacquered copper, so that these conductive strips 6 and the insulating strips 7 can be easily connected. It is advantageous to protect these wires of the insulating strips 7, for example, by coating them against easy damage. It is preferable to use a wire with a small diameter, for example 1 mm, so that the sensor network 5 is woven as finely as possible, thereby achieving more accurate measurements and limiting the influence of the network on the user's comfort. The measurable pressure range of the sensor network 5 can be from 0.1 kPa to 130 kPa. The overall dimensions of the net can be adjusted according to the size of the mat, for example 32 x 32 cm for the seat mat. Thanks to this design of the sensor network 5, this network can be placed directly under the contact surface of the coating 1 for the most accurate measurement and does not have to be uncomfortable for the user 4.

To ensure resistance against moisture or liquid leakage to the pressure sensors 2, these pressure sensors 2 can be stored in a waterproof package, preferably removable stored in the coating 1. The pressure sensors 2 can be firmly attached in the package to ensure their correct placement and thus correct pressure measurement. When using the sensor network 5, for example, it could be sufficient to secure the sensor network 5 against unwanted movement by gluing only their two opposite edges, which can allow faster production and less consumption of material (e.g. glue) while maintaining sufficient attachment. When washing the cover 1, it should be possible to easily remove this cover. For the easiest possible handling, this package can be attached to the cover 1, for example by means of Velcro on two opposite edges of the package. The dimensions of the package depend on the size of the coating 1 and the pressure sensors 2, e.g. when using the sensor network 5 with a size of 32 x 32 cm, a package with dimensions of 40 x 40 cm can be used. For the greater comfort of the user 4, it is advantageous to have, together with the waterproofness of the package, breathability by using a suitable material, for example a textile with a waterproof coating or membrane, specifically, e.g. gore-tex®. Alternatively, this packaging may include a pocket into which the control unit 3 is placed.

Advantageously, the coating 1 can include a source 12 for the control unit 3, preferably also common to the analog multiplexer 11 (see Fig. 1) or possibly other electronic devices. The source 12 can be batteries, e.g. pencil batteries, or preferably an accumulator, e.g. lithium-ion. Source 12 should provide power from a full charge, or battery change, for approximately one month with daily full operation (at least 750 hours). For example, an 18650 type lithium-ion battery with a capacity of 3000 to 3400 mAh could correspond to this. The source 12 can be placed directly in the cover 1, e.g. at the seat cushion, but it can also be placed outside the cover 1, or the entire pillow, if it could interfere with the comfort of the user 4, for example at the backrest cushion. It is advantageous to place the source 12 and/or the control unit 3 with the multiplexer 11 in a waterproof package (e.g. as shown in Fig. 4 and Fig. 5), or seal the connections so that moisture does not penetrate into the inner part of the source 12. U solution shown in Fig. 4, the charging of the source 12 can take place through the microUSB connector, which can be advantageously accessible from the front side

- 4 CZ 36859 U1 with indicated unscrewed plug. Alternatively, the source 12 can be directly part of the control unit 3.

The control unit 3 may include internal electronic equipment in a housing, e.g. made of thermoplastic. Preferably, this case is water-resistant sealed, or the entire control unit 3 is stored in a water-resistant package, which in the case of storage in the coating 1 is removable, e.g. with Velcro. In the exemplary embodiment shown in Fig. 1, the control unit 3 is connected to the source 12, which supplies this control unit 3, and to the analog multiplexer 11. The control unit 3 can also be connected directly to the pressure sensors 2, but when using more pressure sensors 2, it is more advantageous connect an analog multiplexer 11 between the pressure sensors 2 and the control unit 3. Switching on the control unit 3 can be enabled by placing a button on this unit, while when the control unit 3 is stored in the coating 1, a hole will be made in this coating 1 for easier pressing of this button. For easier accessibility, the control unit 3 can therefore be placed in the coating 1 in places where the user 4 will not be in direct contact with the coating 1, e.g. at the seat cushion between the limbs of the user 4. The opening can be advantageously covered with a transparent material so that the button can be seen, but at the same time the water resistance of the coating 1 is maintained. The control unit 3 can, for example, be switched on wirelessly or wired outside of the control unit 3 itself, e.g. an integrated button in a wheelchair on the armrest. An example of a waterproof package is shown in Fig. 4 and Fig. 5. The shape of the package is chosen in relation to the given use, so that its width and possibly height are as small as possible. The inner space of the package, shown in Fig. 5, can be precisely tailored to the control unit 3 and other additional electronics, preferably also the power source 12. The package shown in Fig. 4 can be made to withstand dripping liquid, but this package can optionally modify, for example by adding sealing o-rings, which can increase the protection against liquid ingress into the package. For example, this packaging can be produced by 3D printing or, more advantageously, by plastic injection, which makes it possible to reduce the overall acquisition costs. Exemplary package dimensions can be 46 x 31 x 144 mm, weight can be up to 150 g.

For the most accurate measurement possible, it is advantageous to calibrate the control unit 3 before each use of the system (i.e. the device), or to set the pressure values from the environment given, for example, by the weight of the part of the cover 1 of the entire pillow or blanket, etc. For example, with the seat pad, it is advisable to start the calibration before before user 4 sits on it. This calibration can be started automatically by the control unit 3, advantageously immediately after switching on. The control unit 3 preferably records the pressure values periodically after certain time intervals, e.g. a measurement takes place for a period of 1 to 120 s every 5 to 15 min. Preferably, the control unit 3 includes a memory device (with a capacity, for example, for continuous operation for a period of one month), where the measured data is stored.

The pressure measurement and possible notification of the user 4 can take place, for example, as follows: An acceptable range of pressure values is set, which is determined by the doctor or attending occupational therapist for each user 4 separately. If these permitted values are exceeded during the measurement, the control unit 3 is enabled to perform measurements every second for a certain period of time, e.g. 30 s. If the limit values are still exceeded during this measurement, the control unit 3 informs the user 4. This notification can be carried out, e.g. by means of a sound source 9. The control unit 3 advantageously includes a sound source 9, which may be able to emit various signals - e.g. a certain sound signal when the permissible pressure value is exceeded for a certain period of time, a different sound signal in the event of a fault, when low battery charge, etc. Furthermore, the control unit 3 can also include a light source 8, preferably an LED diode, which can signal the activation/deactivation of the sound signal, the activation/deactivation of the control unit, calibration, exceeding the permitted pressure value for a certain period of time, etc. Control unit 3 can be adapted to perform a so-called self-test, when it checks the functionality of itself and the sensor.

The dimensions of the control unit 3 can be chosen according to the design of the cover 1 and the cushion, e.g. for the seat pad it can have dimensions of 20 x 5 x 4 cm. The control unit 3 can be placed directly in the cover 1, e.g. at the seat cushion, but it can also be placed outside the cover 1 or the entire pillow, if it could disturb the comfort of the user 4, for example at the backrest.

- 5 CZ 36859 U1

Furthermore, according to the exemplary embodiment in Fig. 1, the control unit 3 is wirelessly connected (e.g. via Bluetooth) to the display portable device 10, but it is also possible to establish a connection, for example, by means of a cable. The display portable device 10 can be selected from a set including a mobile phone, a smart watch, a tablet, a laptop, etc. This device is primarily used to display values from the control unit 3 and to control the control unit 3, which could be done, for example, using an installed application designed for this system (i.e. device). Advantageously, the control unit 3 can be able to send the stored data from the measurements to the portable imaging device 10. The portable imaging device 10 can then send this data, for example, to a server, where the attending physician of the user 4 of the system can be allowed access so that these data can be further processed (or, for example, sending this data to the doctor in the form of a report with selected values that he can choose in advance). Using this data, the doctor can, for example, adjust or replace an unsuitable pad or the entire wheelchair, recommend the right exercises, etc. For example, the control unit 3 can, on request, send its device identification code, battery charge level, sensor connection status, absolute values of the measured pressure in the relevant time, all measured pressure data with assigned measurement time, when and what alarm was triggered during the given time period, etc.

It can be displayed both in the form of numerical values and in graphic form, e.g. in the form of a gradient of absolute pressure values or increments over a certain time interval. For the smooth display of values in graphic form on the display portable device 10, a higher sampling frequency, e.g. at least 60 Hz, is advantageous. In the case of a graphic display, together with the pressure measurement data at a given time, the maximum pressure values with dispersion index, contact area (in the case of the dosed seat mat) and average values for example over 12 hours could be displayed. The display portable device 10 can also indicate the total time spent sitting. The setting of the acceptable range of pressure values can be realized precisely using the display portable device 10, which can be more user-friendly than making this setting directly on the control unit 3. Furthermore, it can be advantageous to use the display portable device 10 to determine the interval of regular measurement using the pressure sensors 2, again from in terms of the simplest possible control for the user 4. When the set limit values are exceeded, the user 4 can be notified using the display portable device 10, preferably together with the sound alarm of the control unit 3. The sound source 9 of the control unit 3 can be controlled using the display portable device 10, e.g. .alarm volume adjustment. Similarly, the light source 8 can be adjustable using the display portable device 10, e.g. changing the light intensity depending on the type of alarm. The display portable device 10 can also store a history of how many times the limit value has been exceeded and for which pressure sensors 2. By analyzing the history of exceeded pressure limit values, the control unit 3 with the help of the display portable device 10 can detect the wrong position of the user 4 in time and inform him.

Using the display portable device 10, the so-called self-test of the control unit 3 could be started, which could include a sensor check (whether there was a sensor failure, disconnection of the connecting wire with the analog multiplexer 11), low battery charge levels, or diagnostics of the entire system with display disorders.

Imaging portable device 10 may provide additional functionality, such as counting exercises prescribed by a physician. This function can be implemented by storing successive pressure values (e.g. taken after 1 s) from the beginning of the exercise to its end, which will serve as control values. If, during further measurements, the same sequence of stored pressure values (with pre-defined pressure value and position deviations) occurs, the control unit 3 or the portable device 10 records this as an exercise execution.

Advantageously, the display portable device 10 can include an interface with large control elements (buttons) for users with poor motor skills, possibly even voice control.

Advantageously, for the security of sensitive data about the user 4, the sent data is protected by encryption and is made available only after authorization (e.g. by means of a password and login name), advantageously, for example, access to the application in the display portable device 10 can be protected by a password.

- 6 CZ 36859 U1

To ensure greater comfort for the user 4, the coating 1 can include a filling, e.g. hollow fiber, ball filling, foam, batting, etc. The filling can be placed between the surface of the coating 1 (non-contact parts with the user 4) and the pressure sensors 2, i.e. so that the sensors are as close as possible to the user, especially so that they are not separated from him by padding that would distort the pressure values.

In the exemplary application shown in Fig. 3, the pressure sensors 2 are point (individual) pressure sensors 2 connected conductively in a grid pattern. This design is advantageous to store and attach in its own packaging, so that the pressure sensors 2 can be easily removed from the coating 1.

Cover 1 includes pressure sensors 2, preferably in a removable package, control unit 3, also preferably in a removable package. In addition, a source 12, an analog multiplexer 11 and a user convenience filler 4 can be placed in the cover 1. Advantageously, the equipment of the cover 1 can be removable so that the cover 1 can be effectively cleaned if necessary (eg by washing). For this reason, it is advantageous to make the coating 1 openable, for example in the case of a coating 1 with a rectangular cross-section, so that it is possible to open the coating 1 on three sides in the circumference, e.g. with a zipper. From the point of view of the best possible protection of the internal equipment (cushion including pressure sensors 2), it is advantageous to make the cover 1 from a waterproof material. Due to the frequent contact with the user's body, the material of the coating 1 should also be breathable. For example, gore-tex® can be used advantageously. The dimensions of the cover depend on the use, for example, for a seat pad, the dimensions can range from 36 to 48 cm wide and 38 to 50 cm long.

Coating 1 can be used for different types of pads or supporting parts of a wheelchair, e.g. seat cushions, back rests, forearm rests, etc., but also for different shapes of pads, e.g. circular, rectangular. Alternatively, this coating 1 could be part of a new wheelchair, which could for example have the control unit 3 and the source 12 built into its structure. Coating 1 could also be used, for example, for office chair cushions, car seat cushions and back rests, etc.

The subject of the invention is also a wheelchair including at least four wheels, armrests, a backrest, a seat cushion, etc., and also including a system (i.e. device) for monitoring pressure according to the presented technical solution, for example as described above. Advantageously, this system can be part of the underseat of the wheelchair, possibly the back rest, the forearm rest and other possible support surfaces of the wheelchair. It is possible to use the system only in one pad, e.g. only in the seat cushion, but it is also possible to use this system in several pads on one wheelchair, e.g. in the seat cushion and backrest.

Claims (10)

1. A pressure monitoring device comprising a pillow cover (1), characterized in that the cover (1) includes a set of pressure sensors (2), wherein the set of pressure sensors (2) is arranged along the surface of the cover (1) intended for contact with by the user (4), wherein the set of pressure sensors (2) is removably fixed inside the coating (1), and the device includes a control unit (3) data-connected to the set of pressure sensors (2) and adapted to evaluate the pressure based on the data from the set. 2. Pressure monitoring device according to claim 1, characterized in that the set of pressure sensors is arranged in a sensor network (5). 3. Pressure monitoring device according to claim 2, characterized in that the sensor network (5) comprises two layers, each layer comprising conductive strips (6) separated by insulating strips (7), the conductive strips (6) of one layer lying across conductive strips (6) of the second layer and are separated from them by a material with electrical resistance dependent on pressure. 4. Device for monitoring pressure according to any one of claims 1 to 3, characterized in that the control unit (3) is removably fixed in the coating (1). 5. Pressure monitoring device according to any one of claims 1 to 4, characterized in that it includes a light source (8), wherein the control unit (3) is adapted to light up the light source (8) when a predefined pressure limit value is exceeded after a predefined time interval. 6. Pressure monitoring device according to any one of claims 1 and 5, characterized in that it includes a sound source (9), wherein the control unit (3) is adapted to activate the sound source (9) when a predefined pressure limit value is exceeded after a predefined time interval. 7. Pressure monitoring device according to any one of claims 1 to 6, characterized in that it includes a display portable device (10), wherein the control unit (3) is data-connected to a display portable device (10) adapted to display the output values of the control unit (3) and control unit control (3). 8. Device for monitoring pressure according to any one of claims 1 to 7, characterized in that the coating (1) includes a filling. 9. Pressure monitoring device according to any one of claims 1 to 8, characterized in that it includes a package removably stored in a coating, while a set of pressure sensors (2) is stored in the package. 10. A wheelchair, characterized in that it includes a pressure monitoring device according to any one of claims 1 to 9 for said wheelchair.