Wirelessly usable sensor system for determining human tissue health

Abstract

The invention relates to a wirelessly usable sensor system, wherein the sensor system is suitable for being attached to the skin of a person and comprises the following components: (a) a measuring sensor which is suitable for measuring the oxygen saturation or the tissue perfusion of the skin covered by the sensor system and / or of the underlying tissue and outputting said oxygen saturation or tissue perfusion as a measured value; (b) an evaluation unit which is connected to the measuring sensor, is suitable for evaluating the measured value output by the measuring sensor, for comparing said measured value with a reference value and for outputting a signal if the measured value deviates from the reference value by a predetermined amount, and is suitable for learning the normal state of the tissue of a patient, for identifying patterns in the measured values measured by the measuring sensor by searching for repeating regularities in the sensor data and analyzing deviations from the determined normal state over a certain period of time, and for outputting a signal if the pattern deviates from a regularity; (c) a rechargeable energy store which supplies energy to the measuring sensor and to the evaluation unit and to further optional electronic components, and (d) a housing in which the components (a) to (c) and further optional electronic components are contained, wherein the housing is closed and impermeable to liquid such that the components (a) to (c) and further optional electronic components are protected from liquid. The sensor system is preferably used in medicine in decubitus prophylaxis.

Description

[0001] Wireless sensor system for determining human tissue health

[0002] This invention relates to a reusable sensor system, in particular for determining human tissue health, wherein the sensor system is suitable for being repeatedly applied to the skin of a person.

[0003] A common problem in people with limited mobility is the development of pressure ulcers (decubitus ulcers). A pressure ulcer is a localized injury to the skin and underlying tissue, caused, for example, by prolonged pressure, moisture, shear forces, pre-existing conditions, or friction, which disrupts blood flow to the skin and underlying tissue. Other names include decubitus ulcer, pressure sore, and bedsores. Pressure ulcers can be chronic wounds that occur primarily in patients with reduced mobility, especially if they are bedridden or wheelchair-bound and cannot change their position, remaining in the same position for extended periods. Typically, the weight of the affected (immobilized) body part alone can be sufficient to exceed capillary pressure.If pressure above the capillary pressure threshold persists for an extended period, cells may become undersupplied with oxygen and nutrients. In healthy individuals, the increase in acidic metabolic products and the sustained pressure on nociceptive fibers trigger a reflex to reposition and thus relieve pressure on vulnerable skin areas before permanent damage occurs. In elderly and ill individuals, these reflexes are often impaired or absent, and the necessary tissue relief does not occur. The affected tissue can die, and nerve cells can suffer irreversible damage. Open pressure ulcers represent a potential entry point for pathogens, which can cause not only local infections. A pressure ulcer can therefore lead to serious and potentially fatal complications such as pneumonia or sepsis, for example, through the spread of pus via the bloodstream.Therefore, preventing pressure ulcers through appropriate measures, such as moving and repositioning the patient, is a core task of nursing care. However, nurses are often unaware that a patient is about to develop a pressure ulcer and needs to be moved as soon as possible. In its early stages, a pressure ulcer is often not yet detectable. The standard test used to date is the manual finger test according to Philips. This test is difficult to continuously record and assess completely objectively, as it requires subjective manual work. Therefore, a reliable, objective method for long-term tissue monitoring and early detection of pressure ulcers is essential and is ensured by the sensor system according to the invention.

[0004] Current state-of-the-art systems for this purpose are unsuitable for long-term monitoring of tissue condition in patients because they are not designed for extended use. These systems are often not disinfectable, have short battery life, or are designed as disposable products. Furthermore, these devices are often wired to provide power or data transmission. The presence of a cable, for example, restricts the patient's mobility, which in turn increases the risk of pressure ulcers. These systems also often fail to provide recommendations for action, such as how a patient at increased risk of pressure ulcers should be positioned or repositioned.

[0005] Based on the known state of the art, the invention aims to provide a sensor system that detects the formation of pressure ulcers on a patient's skin or tissue at an early stage, does not restrict the patient's mobility, is easy for nursing staff to use, and can be easily disinfected, thus enabling reusability. The system should also be able to provide timely recommendations for action to prevent the formation of pressure ulcers or to prevent the worsening or even reverse an existing pressure ulcer. Furthermore, the system should reduce costs and electronic waste during continuous operation.

[0006] According to the invention, a wireless sensor system, in particular for determining human tissue health, is provided for this purpose, wherein the sensor system is suitable for being applied to the skin of a person and comprises the following components: (a) a measuring sensor suitable for measuring and outputting as a measured value the oxygen saturation or tissue perfusion of the skin and / or underlying tissue covered by the sensor system;

[0007] (b) an evaluation unit connected to the measuring sensor, which is suitable for evaluating the measured value output by the measuring sensor and comparing it with a reference value, and then outputting a signal when the measured value deviates from the reference value by a predetermined amount, and which is suitable for learning the normal state of a patient's tissue and for recognizing patterns in the measured values ​​by the measuring sensor by searching for recurring regularities in the sensor data and analyzing deviations from the established normal state over a certain period of time, and then outputting a signal when the pattern deviates from a regularity;

[0008] (c) a rechargeable energy storage device that supplies energy to the measuring sensor and evaluation unit as well as other optional electronic components, and

[0009] (d) a housing containing components (a) to (c) and other optional electronic components, wherein the housing is sealed and impermeable to liquids in such a way that components (a) to (c) and other optional electronic components are protected from liquids.

[0010] The integration of the aforementioned electronic components into the liquid-tight housing enables the reuse of the sensor system (in particular the repeated use of the housing with the electronic components contained therein) as well as long-term continuous monitoring and has the following advantages:

[0011] - Disinfectability of the sensor system;

[0012] - Local evaluation of the measurement data within the sensor system results in a smaller amount of data to be transmitted, thereby increasing the system runtime; - Local evaluation can be more reliable, as an interruption of the data connection does not affect the evaluation;

[0013] - The reusability of the sensor system allows patterns in the measured values ​​to be detected over a longer period; in particular, high-resolution measurements with small time intervals are enabled over a long period;

[0014] - Reusability contributes to the reduction of electronic waste and reduces costs;

[0015] - Higher-quality electronic components can be installed, which deliver more accurate measurement results and have a longer lifespan;

[0016] - Human skin or the patient releases fluids in various forms that can damage the electrical components of the sensor system; these are prevented from doing so by the housing;

[0017] - The lifespan of the sensor system is increased;

[0018] - Calibration of the sensor system: Extended use allows for the algorithmic elimination of component fluctuations by comparing measured values ​​over longer periods;

[0019] - Personalization: Long-term and continuous measurement enables personalized pressure ulcer risk assessment;

[0020] - Fewer motion artifacts in the measured values ​​due to cable-induced movement of the sensor;

[0021] - The close spatial integration of sensors and the digital converter reduces the influence of electromagnetic interference on the analog signal;

[0022] - Differentiation between acute and long-term tissue conditions.

[0023] Blood oxygen saturation (SpO2) refers to the percentage of hemoglobin that is saturated with or contains oxygen. In a healthy person, it ranges between 95% and 100%. A significant change in oxygen saturation can indicate impaired tissue perfusion, which can be a sign of tissue damage. Therefore, continuous and long-term monitoring of oxygen saturation at risk areas is essential for pressure ulcer prevention. This oxygen saturation measurement covers the area of ​​skin within the sensor system and is influenced by the blood flow in the underlying or adjacent tissue.Measuring oxygen saturation or tissue perfusion has the advantage that tissue deterioration or recovery can be deduced, and thus recommendations for action can be made, which is not possible with pressure measurement alone. Additionally, it is conceivable that the sensor system according to the invention could also measure the patient's skin temperature in addition to oxygen saturation or tissue perfusion. Preferably, the sensor system according to the invention only measures oxygen saturation or tissue perfusion and / or skin temperature. Furthermore, it is preferred according to the invention that the sensor system according to the invention does not perform any pressure measurement.

[0024] The sensor for measuring tissue oxygen saturation can be a pulse oximeter, a photoplethysmography sensor, a near-infrared spectroscope (NIRS) sensor, or a suitable sensor. Alternative methods for measuring tissue perfusion, such as transcutaneous oxygen measurement, TcPO2 measurement, or ultrasound, are equally usable and also function with the sensor system according to the invention.

[0025] The evaluation unit is suitable for comparing one or more measured values ​​with a reference value (threshold method). In this way, a snapshot of tissue perfusion can be obtained when the measured value falls below the reference value. Additionally, the evaluation unit is also suitable for pattern recognition. "Patterns" within the meaning of the present invention can be statistics in the acquired data and are not limited to temporal trends, although they do include them.

[0026] The sensor system according to the invention enables long-term monitoring of tissue perfusion. Pattern recognition in the sensor data preferably searches for recurring patterns and analyzes deviations from the established normal state, which can be individually defined for each patient, over specific periods. Deviations from the normal state, which can be detected not only by standard threshold methods (comparison between measured value and reference value) but also by the aforementioned pattern recognition, for example, through distance metrics that detect changes in the patient, can be representative of changes in tissue health. Pattern recognition preferably occurs continuously. The detected patterns can be univariate or multivariate. The reference value can be specified as an absolute value or it can be individually adjusted for each patient based on previous measurements of healthy tissue.Alternatively, it can also be set as the average of several previous measurements.

[0027] In other words, the sensor system according to the invention is designed to perform the following actions or be used as follows: First, a baseline patient state is preferably established. For this purpose, the tissue perfusion or oxygen saturation and / or skin temperature of healthy tissue is preferably measured, and the baseline state is established. After repositioning the patient, which may lead to pressure relief or pressure loading of the tissue, the tissue perfusion or oxygen saturation and / or skin temperature can then be measured again over a specific period, for example, 10 to 30 minutes, and the measured values ​​(hereinafter referred to as repositioning measurements) can be recorded. The repositioning measurements are preferably compared with the measurements of the baseline state.Based on this comparison, the sensor system can issue a recommendation for action: If the repositioning measurements deteriorate compared to the measurements in the normal state, the sensor system recommends repositioning the patient (preferably more frequently) (shortening the repositioning interval). If no deterioration is measured, the recommendation is, for example, that the patient should not be repositioned or should be repositioned less frequently (lengthening the repositioning interval). The recording of repositioning measurements can be repeated, and in this way, recovery or deterioration patterns can be identified, which the device can then translate into action instructions: lengthening the repositioning interval if there is no deterioration in the repositioning measurements, or shortening the repositioning interval if the repositioning measurements deteriorate.For example, relocation measurements can be repeatedly recorded and compared over a period of several hours or even several weeks. Furthermore, the sensor system according to the invention is capable of recording the relocation measurements over the aforementioned defined period and comparing the temporal profile of the relocation measurements with previously or subsequently recorded relocation measurements, and deriving and outputting the aforementioned instructions for action. This can be achieved, for example, by comparing distance metrics of the temporal profiles.

[0028] The sensor system according to the invention allows a patient to be monitored over a long period. Tissue reacts differently to pressure application or release depending on the patient's health status. Vital skin parameters, such as oxygen saturation, tissue perfusion, and / or skin temperature, change during pressure application or release. Generally, a rapid normalization of tissue vital parameters upon pressure release indicates healthy tissue. This normalization of vital parameters occurs, for example, within 10 to 30 minutes, which can be compared using distance metrics, among other methods. The sensor system according to the invention can therefore detect repeated repositioning and learn the normal recovery pattern of the skin's vital parameters (a temporal progression). If this normal pattern deviates from the learned pattern, e.g.,If the recovery of oxygen saturation no longer takes 10 minutes, but 15 minutes, this leads to a reduction in the patient-specific repositioning frequency.

[0029] Long-term, continuous data collection allows the predictive model for pressure ulcer development to be broken down into individual aspects. Short-term relevant changes in the univariate or multivariate sensor data can be detected through anomaly detection. This can be based on outliers, such as an abrupt change in tissue perfusion, as well as anomalies over time, such as a prolonged absence of movement data. Continuous, real-time assessment of pressure ulcer risk follows anomaly detection. This prevents the model from having to process measurements that do not follow the same statistical distribution representative of pressure ulcer occurrence. This can prevent false alarms and thus increase the specificity of the model.Continuous pressure ulcer risk assessment benefits from long-term, continuous data acquisition, as this allows for the observation of slow, long-term developments in the condition. These include, for example, relatively gradual deteriorations in tissue perfusion, which may go unnoticed when considering short periods. Furthermore, in an initial phase, the sensor system can learn the normal state of a patient's tissue and thus provide a personalized pressure ulcer risk assessment. This can involve the acquisition of personalized reference values, from which thresholds can be derived, and pattern recognition. A pattern reflecting the normal state of the tissue could, for example, be the increase in oxygen saturation—i.e., a recovery of tissue perfusion—following a detected repositioning of the patient. If this pattern deviates from the historical data after prolonged bed rest, it may indicate a change in the tissue condition.

[0030] Additional influencing factors, such as age, gender, weight, pre-existing conditions, and pressure ulcer risk scales, can be included in the continuous risk assessment. Furthermore, manual tests and input from caregivers can also be considered. A signal is then generated based on the evaluation.

[0031] Preferably, the evaluation unit is suitable for analyzing the recovery of tissue perfusion and thus the tissue condition in the event of a detected repositioning of the patient by comparing learned temporal patterns with the history using distance metrics.

[0032] In contrast to previous methods that only allow a comparison of sensor values ​​at different skin sites or the analysis of historical data over a period of a few hours, the present invention enables the analysis of the entire historical course of a patient's sensor / time series data by storing relevant temporal patterns. For this purpose, the temporal progressions of the sensor data are preferably marked in memory where a relevant event, such as repositioning performed independently or by nursing staff, led to a change in tissue pressure. In addition to short-term changes, the invention also allows for the analysis of long-term changes.Deterioration of tissue condition, detected by means of anomaly detection, allows the comparison of all relevant historical time courses with the current reaction of the skin to pressure loading or unloading, and the reaction of the skin's vital data to this change to be determined as a health indicator.

[0033] Temporal pattern recognition also allows for event-based analysis (e.g., when the patient moves or a repositioning is detected) that is not based on fixed intervals (as is otherwise common in nursing care, but also in comparable measurement systems). This makes it possible to differentiate between stress and recovery cycles.

[0034] Pattern recognition also enables a long-term historical assessment of pressure ulcer risk over time. Data over several hours can be evaluated using pattern recognition. Thus, 1,000 or more data points or time series detected in response to pressure loading or unloading can be used to assess pressure ulcer risk. In current nursing practice, only individual measurements or subjective testing methods are considered, and pressure ulcer risk is evaluated only at the current point in time. In contrast, the present invention allows for a temporal analysis of pressure ulcer risk and can therefore also reveal gradual developments.

[0035] Furthermore, pattern recognition over time can also be used to identify skin recovery as a health indicator: Detecting and storing temporal skin recovery patterns allows for historical comparisons and thus the derivation of changes in tissue health. The speed at which vital parameters, such as tissue oxygen saturation or skin temperature, recover after skin stress is reduced are indicators of tissue health. These skin recovery patterns enable a personalized assessment of tissue health. These skin recovery patterns can be determined directly for each patient on a microcontroller, i.e., "at the edge." This makes a personalized assessment of tissue health possible.

[0036] Long-term monitoring of tissue health not only allows for the immediate issuance of relevant alerts for acute repositioning, but also enables adjustments to the care plan. This means, for example, that the repositioning interval, i.e., the frequency of repositioning, can be specifically tailored to the individual needs of a patient. Furthermore, through point-in-time measurements and pattern recognition over time, short-term (e.g., creases in clothing or bed sheets) and long-term risk factors (e.g., deteriorating health, poor nutrition, etc.) can be distinguished.

[0037] The integrated evaluation unit in the sensor system allows for direct analysis of changes in skin oxygen saturation without the need to send the data to an external unit. This ensures direct, energy-efficient data analysis, even offline, and thus more reliable monitoring. The system is also more robust against data transmission errors because the evaluation unit is integrated into the housing. The output signal can be analog or digital and triggers an alarm, preferably audible, visual, or haptic, such as a sound or a flashing LED light, or displayed on a screen of a device like a PC, tablet, or mobile phone. This directly notifies an authorized person that action is required and can also provide further recommendations.

[0038] The reusability of the sensor system eliminates the need for disposal after use. This allows for the use of higher-quality electronic components that deliver more accurate measurements and a longer lifespan. Since the sensor system does not require disposal after a single use, operating costs are reduced.

[0039] In one embodiment of the reusable sensor system according to the invention, it is preferred that it includes a transmitter unit for sending the signal to a display / signal output device. The signal can be sent, for example, to a mobile phone, a PC, or any device suitable for issuing, for instance, an optical, haptic, or visual warning. For example, an app could be provided on a smartphone that, as a result of a signal received from the sensor system, displays a notification on the screen, emits a sound, or vibrates. Furthermore, in addition to the warning, instructions for action could also be displayed, specifying, for example, which area(s) of the person's skin are at risk and whether and how the person needs to be moved. The received signal can also include the time course of the measured oxygen saturation.Using multiple sensor systems on a single person simultaneously allows for the identification of particularly vulnerable areas. The sensor system's self-contained data processing enables the simultaneous monitoring of numerous patients without requiring any evaluation steps from the external receiver. The simplified receiver requirements allow for cost-effective manufacturing, or the use of existing display devices.

[0040] The sensor system should be placed near, but preferably not directly on, areas at risk for pressure ulcer development. These risk areas can be on the lower back, but also on the heel, back of the head, or elbows. The sensor system then monitors a certain surrounding area.

[0041] Another possible application is for the prevention of foot ulcers in diabetics. For this purpose, the sensor system is worn on the foot and integrated, for example, into a shoe insole, flexible plaster, or sock. This also includes mobile patients with neuropathy.

[0042] The rechargeable energy storage device, which supplies energy to the measuring sensor and evaluation unit as well as other optional electronic components, can be a battery or a supercapacitor.

[0043] The rechargeable energy storage unit ensures that the electronic components of the sensor system are powered without a cable from a power source, such as a wall socket. By eliminating external wiring, the patient's mobility is not restricted. A cable protruding from the sensor system, which can be uncomfortable in an incorrect lying position and pull on the sensor, automatically reduces the patient's comfort and increases the risk of pressure ulcers. Reduced mobility and a potential inhibition of movement due to diminished comfort lead to even less movement, further increasing the risk of pressure ulcers. Therefore, the rechargeable energy storage unit enhances the sensor system. For pressure ulcer prevention to be effective, measurements should be taken at regular intervals.A pressure ulcer can develop within an hour or even less, and may not be externally detectable during this period. With measurements taken only hourly or less frequently, the crucial moment to recognize the need for patient repositioning might be missed. Therefore, more frequent measurements are advantageous. Transmitting data consumes a relatively large amount of energy and drains the battery. Data analysis directly within the sensor system eliminates the need for frequent transmission of measurements to an external evaluation unit. This direct analysis saves energy by reducing the need for constant data transmission and allows for better monitoring, as measurements can be taken more frequently, thus reducing the strain on the battery.The lower energy consumption reduces the frequency of charging cycles, which in turn improves user-friendliness. Additionally, the patient is not exposed to increased risk due to, for example, extended periods when no sensor system is attached to their skin.

[0044] A base station, preferably supporting inductive charging, is provided for charging the energy storage device.

[0045] This base station can also be used to issue the aforementioned alarm, display the aforementioned signal, or upload data to a server.

[0046] In a further embodiment of the sensor system according to the invention, it is preferred that the housing extends in a longitudinal direction X, a transverse direction Y orthogonal thereto, and a vertical direction Z orthogonal to both of these directions, wherein the vertical direction Z has a maximum height of 10 mm, more preferably a maximum height of 8 mm, even more preferably a maximum height of 5 mm, and most preferably a maximum height of 2 mm. The housing preferably has rounded edges and / or corners, since sharp edges or corners would increase the risk of pressure ulcers.

[0047] The sensor system according to the invention preferably has a specially adapted, miniaturized housing into which the electronic components can be directly integrated. Conductive traces can be applied directly to the housing (e.g., using a 3D MID "Molded Interconnected Device") to save on overall height. The elimination of cables and an energy-saving system with data processing in the evaluation unit enable a flat, cable-free sensor system with a small, flat energy storage device. The absence of cables also allows for improved signal quality, which is necessary for measuring small changes in vital signs, as motion artifacts have less of an impact. The energy-saving design and the computationally efficient algorithms with low required transmission power result in minimal heat generation and eliminate the need for space-consuming cooling systems / heat conductors.Embedding electronic components or sensors in the circuit board or housing can make the system thinner. Choosing flexible and / or thin circuit boards, as well as energy storage devices, allows for a further reduction in overall height. Mechanical stability and protection for the electronics can still be ensured by using the circuit board or other robust components as structural elements. Further system integration, such as the use of custom-designed integrated circuits (ASICs), can make the system even smaller and more energy-efficient. Encapsulating the electronics in padding material or the housing material eliminates unnecessary dead space and reduces overall height. The dense integration of energy storage, sensors, and the evaluation unit can be achieved by selecting specialized insulating materials such as PTFE, PU, ​​ceramic, or epoxy resin.

[0048] The sensor system according to the invention preferably has a skin-friendly housing material that is preferably lightweight, stable and can be manufactured thinly, such as carbon fibers or plastics such as PC, PEEK or TPU.

[0049] The sensor system according to the invention preferably includes a fastening device for attaching the sensor system to the skin. The fastening device is preferably replaceable. The fastening device can be, for example, a belt, garment, or bandage, each without adhesive; a skin-compatible adhesive, preferably a liquid adhesive / silicone; a plaster that presses the sensor system housing against the skin from the outside; or adhesive strips that can be peeled off and reapplied (such as double-sided adhesive tape). Equally conceivable is a fastening device that is attached to the sensor system housing by a fixing system. The fixing system can have a recess or pocket, a snap fastener, a hook-and-loop fastener, a press fit, or a twist lock to fix the housing to the fastening device. The fastening device can include padding for skin-friendly wear.

[0050] The housing preferably comprises, or is preferably made of, an elastic or flexible material. An elastomeric plastic, such as silicone, which is skin-friendly or biocompatible, can be used as the material.

[0051] The sensor system according to the invention can include further sensors for acquiring additional sensor data on the skin, such as temperature, humidity, pressure, and tissue perfusion using ultrasound or laser Doppler for improved analysis of the tissue condition. Measuring skin temperature allows conclusions to be drawn about tissue perfusion as well as possible inflammation.

[0052] The sensor system according to the invention can include further sensors for detecting patient movements (IMU) for improved determination of the pressure ulcer risk by detecting micro- and macro-movement.

[0053] A further embodiment of the invention relates to the reusable sensor system according to the invention for use in medicine. In other words, the present invention also relates to the use of the reusable sensor system according to the invention in medicine.

[0054] A further embodiment of the invention relates to the reusable sensor system according to the invention for use in the prophylaxis of pressure ulcers, in particular decubitus ulcers, and foot ulcers, or for monitoring wound healing, for monitoring the effects of preventive measures, such as repositioning or applying cream to the patient or during dietary changes, or for investigating the tissue reaction to influences such as temperature, nutrition or medication.In other words, the present invention also relates to the use of the reusable sensor system according to the invention for determining human tissue health, in particular for use in the prophylaxis of pressure ulcers, especially decubitus ulcers, and foot ulcers, or for monitoring wound healing, for monitoring the effects of preventive measures, such as repositioning or applying cream to the patient or during dietary changes, or for investigating the tissue response to influences such as temperature, nutrition or medication.

[0055] In other words, the present invention relates to a method for the prophylaxis of pressure ulcers, in particular decubitus ulcers, and foot ulcers, or for monitoring wound healing, for monitoring the effects of preventive measures, such as repositioning or applying cream to the patient or during dietary changes, or for investigating the tissue reaction to influences such as temperature, nutrition or medication, using a sensor system according to the invention, wherein the sensor system is applied to the skin / tissue of a patient.

[0056] It is preferred that, in the inventive use or method, several measurements are taken from the same patient at intervals of less than 30 minutes, more preferably less than 20 minutes, even more preferably less than 10 minutes, and most preferably less than 5 minutes. This is important to enable continuous tissue monitoring.

[0057] In the use or method according to the invention, previously acquired measured values ​​can be taken into account in the continuous assessment of tissue health. This enables the pattern recognition described above and the consideration of slow, long-term disease developments.

[0058] The present invention is now illustrated by way of example with reference to the following figures 1 to 3: Figure 1 shows a schematic top view of a sensor system according to the invention;

[0059] Figure 2 shows a lateral cross-section of a sensor system according to the invention;

[0060] Figure 3 shows a sensor system according to the invention with a base station with charging function.

[0061] Figure 1 shows a schematic top view of a sensor system 100 according to the invention, comprising a housing 2 for reusable electronic components 3, preferably on a replaceable mounting device 1, which may be designed as a patch or adhesive unit. The housing 2 contains at least one measuring sensor 5 for measuring oxygen saturation, an evaluation unit 4, and a rechargeable energy storage device 7 for powering the electronic components 3. The sensor system 100 may also include a transmitter 6 for sending the signal evaluated by the evaluation unit to a display / signal output device, as well as electronics for preferably wireless charging 9. The sensor system 100 according to the invention may also include a placeholder 8 within the housing 2 for a further sensor or for monitoring, for example, other patient parameters in addition to oxygen saturation.

[0062] Figure 2 shows a side cross-section of a sensor system 100 according to the invention as shown in Figure 1. The fastening device 1 is preferably designed as a patch or adhesive unit and may include a fixing system 10 for receiving the housing 2. The entire sensor system 100 preferably has a height Z of less than or equal to 10 mm.

[0063] Figure 3 shows an arrangement of a sensor system 100 according to the invention with a housing 2 and a mounting device 1 on a base station 12. The base station 12 can have a charging function for preferably wireless charging of the energy storage device 7. The base station 12 optionally has a communication module for data upload. List of reference numerals:

[0064] 100 sensor system

[0065] 1 replaceable fastening device (plaster / adhesive unit)

[0066] 2 housings for electronic components

[0067] 3 Reusable electronic components

[0068] 4 evaluation units

[0069] 5 Oxygen saturation measuring sensor

[0070] 6 transmitter units

[0071] 7 Rechargeable Energy Storage

[0072] 8 Placeholders for additional measuring sensors / additional measuring sensor

[0073] 9 Electronics for (wireless) charging

[0074] 10 Fixation system

[0075] 11 Adhesive surface

[0076] 12 Base station with charging function (and optionally a communication module for data upload)

Claims

Patent claims 1. Wireless sensor system (100), in particular for determining human tissue health, wherein the sensor system (100) is suitable for being applied to the skin of a human being and comprises the following components: (a) a measuring sensor (5) suitable for measuring and outputting as a measured value the oxygen saturation or tissue perfusion of the skin covered by the sensor system (100) and / or the underlying tissue; (b) an evaluation unit (4) connected to the measuring sensor (5), which is suitable for evaluating the measured value output by the measuring sensor (5) and comparing it with a reference value, and then outputting a signal if the measured value deviates from the reference value by a predetermined amount, and which is suitable for learning the normal state of a patient's tissue and for recognizing patterns in the measured values ​​measured by the measuring sensor (5) by searching for recurring regularities in the sensor data and analyzing deviations from the determined normal state over a certain period of time, and then outputting a signal if the pattern deviates from a regularity; (c) a rechargeable energy storage device (7) that supplies energy to the measuring sensor (5) and the evaluation unit (4) as well as other optional electronic components (8), and (d) a housing (2) containing components (a) to (c) and other optional electronic components, wherein the housing (2) is sealed and impermeable to liquids, such that the components (a) to (c) and other optional electronic components are contained within the housing (2) and are contained within the housing (2) and are contained within the housing (2) and are contained within the housing (2) and are contained within the housing (2) and contain liquids. Components are protected from liquid.

2. Sensor system (100) according to claim 1, comprising a transmitting unit (6) for sending the signal to a display / signal output device.

3. Sensor system (100) according to claim 1 or 2, wherein the housing (2) extends in a longitudinal direction X, a transverse direction Y orthogonal thereto and a vertical direction Z orthogonal to these two directions, wherein the vertical direction Z has a maximum height of 10 mm.

4. Sensor system (100) according to one of claims 1 to 3, comprising an interchangeable fastening device (1) for attaching the sensor system (100) to the skin.

5. Sensor system (100) according to claim 4, wherein the fastening device (1) has a pad for skin-friendly wearing.

6. Sensor system (100) according to one of claims 1 to 5 for use in medicine, in particular in the prophylaxis of pressure ulcers, especially decubitus ulcers, foot ulcers, or for monitoring wound healing, for monitoring the effects of preventive measures, such as repositioning or applying cream to the patient or in the case of dietary changes, or for investigating the tissue reaction to influences, such as temperature, nutrition or medication.

7. Use of a sensor system (100) according to any one of claims 1 to 5 for determining human tissue health.

8. Use according to claim 7, wherein multiple measurements are taken on the same patient at intervals of less than 30 minutes.

9. Use according to claim 8, wherein previously acquired measurements are taken into account in the continuous assessment of tissue health.

10. Use according to claim 9, wherein, upon detection of a deviation of measured values ​​from previously recorded measured values, a recommendation for action is issued.

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