Prothesenliner

Abstract

Prosthetic liner for placement on an amputation stump, wherein the prosthetic liner consists at least partially of an elastic liner material (2), characterized in that at least one barometric pressure sensor (4) is arranged in the liner material (2), which is configured to measure a pressure prevailing in the elastic liner material (2) when the prosthetic liner is in place, wherein the at least one barometric pressure sensor (4) has a sensor housing (8) with an opening (10) that is completely covered by the liner material (2), wherein a membrane is located in the sensor housing (8) which is equipped with a piezoresistive strain gauge.

Description

[0001] The invention relates to a prosthetic liner for arranging on an amputation stump, wherein the prosthetic liner consists at least partially of an elastic liner material.

[0002] Such prosthetic liners, in which the liner material is silicone or polyurethane, for example, have long been known in the state of the art. They are pulled over the amputation stump and form an intermediate layer between the patient's amputation stump and a prosthetic socket, which is traditionally made of a rigid material, such as a carbon fiber composite. The prosthetic liner has several functions. In vacuum sockets, which are held in place on the amputation stump by a negative pressure created between the prosthetic liner located on the amputation stump and the prosthetic socket, the prosthetic liner is responsible, among other things, for sealing the space between them. At the same time, however, it also serves to pad, particularly sensitive areas of the amputation stump that should not be subjected to pressure or should only be subjected to limited pressure.

[0003] The production of a prosthetic socket, which should ideally be individually adapted to the amputation stump and its shape and design, is still a complex and cost-intensive process. A particular problem is that locating pressure points is difficult, as they can only be detected when the prosthetic socket is in place and thus only inside the prosthetic socket. Nevertheless, the detection of such pressure points is of great importance for an optimal fit of the prosthetic socket, as the shape and design of the prosthetic socket often needs to be reworked in these areas. Failure to do so can lead to wounds, pressure sores, or pain. This naturally reduces comfort and lowers acceptance of the prosthesis.

[0004] Therefore, various methods are known from the state of the art to measure the pressure that exists between the amputation stump and the outside of the liner when the prosthesis is in place and that is exerted, for example, by the socket on the liner.

[0005] US 2017 / 0020694 A1, for example, discloses a liner construction in which a large number of force measuring elements are distributed across the sensor body in order to measure the forces acting on the liner as comprehensively as possible. A disadvantage, however, is that the arrangement of such a large number of measuring sensors results in significant design effort. In the cited prior art, the individual sensors must either be connected separately to an electrical power supply, which results in significant design effort, or, as described in one of the exemplary embodiments, are connected via material strips that run lengthwise and crosswise across the liner body. The sensors are arranged at the intersection points of these material strips. The power supply is then provided via these material strips.However, this usually compromises the elastic properties of the prosthetic liner, as the material strips are limited in their elasticity due to the required electrical conductivity. Furthermore, the construction effort for such a liner is enormous, as the various material strips must not only be inserted into the liner material but also be precisely positioned within it.

[0006] The invention is therefore based on the object of improving a prosthetic liner in such a way that the pressure acting on the liner can be determined, but the production of such a prosthetic liner is simple and possible without impairing the mechanical properties of the liner.

[0007] The invention solves the stated problem by a prosthetic liner according to the preamble of claim 1, which is characterized in that at least one barometric pressure sensor is arranged in the liner material, which is designed to measure a pressure prevailing in the elastic liner material when the prosthetic liner is in the applied state, wherein the at least one barometric pressure sensor has a sensor housing with an opening that is completely covered by the liner material, wherein a membrane is located in the sensor housing, which is equipped with a piezoresistive strain gauge.

[0008] Compared to other pressure sensors previously installed in liner materials, a barometric pressure sensor has the advantage of being very small and yet able to determine the pressure acting on the liner material very precisely. It has a housing in which a membrane is arranged, which is equipped with piezoresistive strain gauges. These are advantageously made of a semiconductor material. If such piezoresistive strain gauges are deformed, a reorientation of the atoms occurs at the crystal level, which changes the specific resistance. The housing of the barometric pressure sensor, in which the membrane with piezoresistive strain gauges is located, has an opening that is completely covered by the liner material. This creates a completely or at least almost airtight interior of the housing in which the membrane is located.

[0009] If pressure is now applied to the liner material at the location of the sensor, the elastic liner material partially penetrates through the opening into the housing of the barometric pressure sensor, thereby reducing the air-filled volume of the housing. This causes an increase in pressure inside the sensor housing, which deforms the diaphragm inside the sensor housing. This deformation of the diaphragm necessarily results in a deformation of the piezoresistive strain gauges arranged on the diaphragm, which changes the resistance of the strain gauges. This can be measured and evaluated, allowing conclusions to be drawn about the pressure inside the sensor housing and thus about the external pressure.

[0010] In a preferred embodiment of the prosthetic liner, the at least one barometric pressure sensor has an electronic data processing device, in particular an analog-to-digital converter, which is configured to convert measured values ​​from the barometric pressure sensor into digital signals. The at least one barometric pressure sensor advantageously has a circuit board in or on its housing, on which a corresponding microcontroller or an integrated circuit is mounted, which acts as an analog-to-digital converter. The measured values ​​recorded by the sensor can thus be converted into digital signals. Particularly preferably, the electronic data processing device of the barometric pressure sensor is designed such that it can also process electronic signals, in particular digital signals.In this way, it is possible to address the barometric pressure sensor, for example, via an electrical control, in particular in the form of an electronic data processing device, which is arranged, for example, at another location on the prosthetic liner or on an external device, and, for example, to query measured values.

[0011] The prosthetic liner advantageously has several, advantageously more than 10, particularly preferably more than 25 barometric pressure sensors, all arranged in the liner material. This makes it possible to determine the pressure acting on the prosthetic liner at different locations. The barometric pressure sensors can be evenly distributed throughout the prosthetic liner to obtain the most complete picture of the pressure distribution possible. Alternatively, it is also possible to equip certain areas of the prosthetic liner, which are intended to cover particularly pressure-sensitive areas of the amputation stump, with a larger number of barometric pressure sensors in order to obtain a particularly detailed picture of the pressure distribution. Areas of the prosthetic liner intended to cover less pressure-sensitive areas of the amputation stump can be designed with fewer or no pressure sensors.

[0012] Advantageously, the plurality of barometric pressure sensors are interconnectable or connected to each other via a bus system. Advantageously, an I 2 A C-Bus (Intra-Integrated Circuit Bus) is used. The barometric pressure sensors are preferably connected to each other and to an electronic data processing device, in particular a further microcontroller, via the bus system. This microcontroller can be located elsewhere on the prosthetic liner or be part of an external device. For example, it is sufficient for the prosthetic liner to have a bus system interface, designed, for example, as a plug or socket. A corresponding interface, such as a socket or plug, is connected to the liner's interface if necessary, completing the bus system.

[0013] The particular advantage of this type of communication between the electronic data processing device and the barometric pressure sensors is that a serial bus can be used, eliminating the need to connect each sensor individually with power and, if necessary, data cables. Instead, the individual pressure sensors can be connected in series, preferably using only one cable with multiple wires. These are necessary for powering the individual barometric pressure sensors and for data transmission. Preferably, four wires are used.

[0014] During operation of such a bus system, which connects multiple barometric pressure sensors to an electronic data processing device, electronic request signals can be sent from the electronic data processing device to each of the barometric pressure sensors, thus querying and identifying the measured values ​​of each individual sensor. Each sensor preferably has an electronic identifier that is used to address the individual sensors and identify the measurement signals emitted by the barometric pressure sensors, particularly via their own electronic data processing devices, i.e., in particular, the analog-to-digital converters. This also reduces the design effort and thus the production costs.

[0015] The prosthetic liner preferably has an electronic data storage device for storing sensor data from the at least one barometric pressure sensor. Of course, sensor data from multiple barometric pressure sensors can also be stored in the electronic data storage device. The data stored in the electronic data storage device can be read out via an existing interface, which can be wireless or wired, and evaluated at a later time.

[0016] The prosthetic liner preferably has a communication interface for transmitting sensor data from the at least one barometric pressure sensor. The communication interface is advantageously configured for wireless communication, in particular via Bluetooth, WLAN, or radio. In this way, sensor data from the at least one barometric pressure sensor can be transmitted directly or from a buffer in the form of an electronic data storage device from the liner to an external device, for example a computer, where it can be evaluated. This advantageously occurs in real time. A patient wearing a prosthetic liner described here to determine the pressure distribution in a prosthetic socket that may still need to be adjusted can thus be monitored in real time.The individual sensor data can be directly assigned to the individual movement sequences that the patient performs with the prosthesis and the prosthetic liner described here, and the patient himself also gets a quick impression and can thus compare the feeling of pressure that occurs on the amputation stump with the measured data.

[0017] Preferably, the at least one barometric pressure sensor is embedded, advantageously cast, in the liner material. Because the at least one barometric pressure sensor is completely surrounded by the liner material, it is protected, in particular, from external contamination or excessive mechanical stress. Furthermore, the manufacturing process is significantly simpler if the sensors are cast into the material. They are arranged at the desired locations, including the necessary connecting cables for power and data transmission, in the desired positions in a liner mold, which is then cast.Of course, other components of the liner that are known from the prior art, for example a distal cap, a connecting element for connecting to a prosthetic shaft, additional layers of other materials and in particular textile fabrics, can also be used in a liner described here.

[0018] The invention further achieves the stated object by a system comprising a prosthetic liner of the type described here and an electronic data processing device. The system is characterized in that the data processing device is configured to evaluate the sensor data of the at least one barometric pressure sensor and has a display device for displaying the evaluated sensor data two-dimensionally and / or three-dimensionally. This creates a two-dimensional or even three-dimensional "map" on which the pressure distribution of the liner can be clearly displayed and quickly understood by the observer.

[0019] The invention is explained in more detail below with reference to the accompanying drawings. It shows: Fig. 1 - the schematic sectional view through a sensor arranged in the liner material, Fig. 2 - the schematic representation of a bus system, Fig. 3 - the schematic representation of the positioning of different sensors in the liner material and Fig. 4 - the schematic representation of a liner according to an embodiment of the present invention.

[0020] Fig. Figure 1 shows a sectional view through part of a prosthetic liner according to an embodiment of the present invention. A barometric pressure sensor 4 is arranged in a liner material 2, which is preferably elastic and is mounted on a circuit board 6. The barometric pressure sensor 4 has a sensor housing 8 with an opening 10 in which a membrane 12 is located, which is preferably equipped with piezoresistive strain gauges. These are not shown for the sake of clarity.

[0021] The circuit board 6 has a data processing device (not shown), in particular an analog-digital converter, in order to convert the measured values ​​determined by the barometric pressure sensor 4 into digital signals and to transmit them to an electronic control device or an electronic data processing device.

[0022] If pressure is now applied to the liner material 2 along the arrows 14, the liner material 2 is pressed through the opening 10 into the interior of the sensor housing 8. This changes the air-filled volume inside the sensor housing 8 by the volume ΔV. The pressure inside the sensor housing 8 increases, and the membrane 12 is deformed, changing its resistance. This allows conclusions to be drawn about the pressure along the arrows 14.

[0023] Fig. Figure 2 shows a schematic representation of a bus system that can be used to connect multiple barometric pressure sensors 4 to an electronic control device. Multiple barometric pressure sensors 4 are arranged in a manner designated as "slaves." The "master" is formed by an electronic control device 16, which can be in the form of an electronic data processing device, in particular a microcontroller.

[0024] Four lines 18 can be seen, via which the individual barometric pressure sensors 4 are connected to the electronic control device 16. Between the two lower and the top of the four lines 8, a so-called pull-up resistor 20 is arranged, which only serves to keep the lines at "logic 1" when the bus is free.

[0025] The top two lines 18 in Fig. 2 are intended for the power and voltage supply. The abbreviation "VCC" stands for a positive voltage supply. The abbreviation "GND" is ground. The two upper lines 18 are therefore only intended for the power supply of the various barometric pressure sensors 4.

[0026] The two lower lines 18 are the so-called data lines. The upper one is the so-called SDA (Serial Data Line), while the lower of the two lower lines 18 is called the clock line (SCL). The use of such a bus system has long been known in the art, even if it has not yet been used for sensors within a liner material. This can already be seen from Fig. 2 illustrates the great advantage of this type of communication system. The four lines 18 can be laid as a single cable, eliminating the need to connect each barometric pressure sensor 4 individually to the electronic control device 16.

[0027] Fig. 3 shows the schematic arrangement.

[0028] The individual boxes, which are provided with a number, identify barometric pressure sensors 4, which are arranged in the liner material 2. The bold black line, by which the individual barometric pressure sensors 4 are connected, represents the bus line 22, in which the four Fig. 2 known lines 18 are included. The barometric pressure sensors 4, numbered 14, 28, 42, and 56, are each connected to a pull-up resistor 20 in the illustrated embodiment, while redundant lines that are not required are shown narrower. It can be seen that the number of lines is significantly reduced compared to a prior art system in which each pressure sensor must be individually connected to an electronic control device. The manufacturing costs and complexity are reduced accordingly.

[0029] In addition, controlling the various barometric pressure sensors 4 is particularly easy, as this can also be done via the bus line 22. Each barometric pressure sensor 4 has a digital identifier that can be used to address each pressure sensor individually, so that the measured values ​​of different sensors can be read out one after the other.

[0030] Fig. Figure 4 shows a liner according to an embodiment of the present invention. A plurality of barometric pressure sensors 4 are inserted into the liner material 2 and are connected to one another via a bus line 22. An opening is located in the distal end of the liner through which the bus lines 22 can be led out of the liner and the liner material 2 and connected, for example, to an electronic control device. List of reference symbols: 2 Liner material 4 Barometric pressure sensor 6 circuit boards 8 sensor housings 10 Opening 12 Membran 14 Arrow 16 electronic control device 18 Line 20 pull-up resistor 22 Bus line

Claims

[1] Prosthetic liner for arranging on an amputation stump, wherein the prosthetic liner consists at least partially of an elastic liner material (2), characterized by in that at least one barometric pressure sensor (4) is arranged in the liner material (2), which is designed to measure a pressure prevailing in the elastic liner material (2) when the prosthesis liner is in the applied state, wherein the at least one barometric pressure sensor (4) has a sensor housing (8) with an opening (10) which is completely covered by the liner material (2), wherein a membrane is located in the sensor housing (8) which is equipped with a piezoresistive strain gauge. [2] Prosthetic liner according to claim 1, characterized bythat the at least one barometric pressure sensor (4) has an electronic data processing device, in particular an analog-digital converter, which is designed to convert measured values ​​of the barometric pressure sensor (4) into digital signals. [3] Prosthetic liner according to claim 1 or 2, characterized by that several, preferably more than 10, particularly preferably more than 25 barometric pressure sensors (4) are arranged in the liner material. [4] Prosthetic liner according to claim 3, characterized by that the plurality of barometric pressure sensors (4) are connected by a BUS system, preferably an I 2 C-Bus (inter-integrated circuit BUS) can be connected or is connected to an electronic data processing device (16), in particular a microcontroller. [5] Prosthetic liner according to one of the preceding claims, characterized bythat the prosthetic liner has an electronic data memory for storing sensor data of the at least one barometric pressure sensor (4). [6] Prosthetic liner according to one of the preceding claims, characterized by that the prosthetic liner has at least one communication interface to transmit sensor data of the at least one barometric pressure sensor (4). [7] Prosthetic liner according to claim 6, characterized by that the communication interface is set up for wireless communication, in particular Bluetooth, WLAN or radio communication. [8] Prosthetic liner according to one of the preceding claims, characterized by that the at least one barometric pressure sensor (4) is embedded, preferably cast, in the liner material (2). [9] System comprising a prosthetic liner according to one of the preceding claims and an electronic data processing device, characterized bythat the data processing device is configured to evaluate the sensor data of the at least one barometric pressure sensor and has a display device to display the evaluated sensor data two-dimensionally and / or three-dimensionally.

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