Simulator device

Abstract

The present invention provides a simulator device (1) mimicking human tissue for calibrating a medical or non-medical device (2). The simulator device (1) comprises at least one optically active foil (3a-d) for dynamically varying optical tissue properties, at least one skin-mimicking area (4a-d) arranged on top of said at least one optically active foil (3a-d), wherein said skin-mimicking area (4a-d) is arranged for receiving said medical or non-medical device (2) during said calibration, and wherein said at least one optically active foil (3a-d) is further configured for absorbing and reflecting light emitted by said medical or non-medical device (2) during said calibration depending on a voltage applied to said optically active foil (3a-d). The simulator device (1) further comprises at least one optical feedback sensor (5a-d) for measuring the optical response of said at least one optically active foil (3a-d), and a control unit (6) configured for controlling the voltage applied to said at least one optically active foil (3a-d) and for varying the applied voltage dependent on information from said at least one optical feedback sensor (5a-d).

Claims

1. A simulator device mimicking human tissue for calibrating a medical or non-medical device, said simulator device comprising at least one optically active foil for dynamically varying optical tissue properties, at least one skin-mimicking area arranged on top of said at least one optically active foil, wherein said skin-mimicking area is arranged for receiving said medical or non-medical device during said calibration, and wherein said at least one optically active foil is further configured for absorbing and reflecting light emitted by said medical or non-medical device during said calibration depending on a voltage applied to said optically active foil, and wherein said simulator device further comprises at least one optical feedback sensor for measuring the optical response of said at least one optically active foil, and a control unit configured for controlling the voltage applied to said at least one optically active foil and for varying the applied voltage dependent on information from said at least one optical feedback sensor.

2. A simulator device according to claim 1, wherein the simulator device comprises a plurality of optically active foils arranged in a stack.

3. A simulator device according to claim 2, wherein different optically active foils are configured for absorbing different wavelengths of light.

4. A simulator device according to claim 2, wherein the simulator device comprises one optical feedback sensor per layer of optically active foil.

5. A simulator device according to claim 1, wherein the simulator device comprises a plurality of skin-mimicking areas representing different skin tones.

6. A simulator device according to claim 5, wherein at least two of the plurality of skin-mimicking areas are arranged on top two different individually controlled stacks of optically active foils.

7. A simulator device according to claim 1, wherein said optical feedback sensor comprises at least one photo-detector, and wherein the control unit is configured for controlling that the voltage applied to said at least one optically active foil produces the desired spectral properties of the at least one optically active foil based on information from the at least one photo-detector and wherein the control unit is further configured for adjusting said applied voltage if the measured spectral properties are outside a targeted range.

8. A simulator device according to claim 7, wherein the control unit is further configured for reversing the polarity of the voltage applied to the at least one optically active foil if the spectral properties of the at least one optically active foil is outside a targeted absorption range.

9. A simulator device according to claim 7, wherein the spectral properties are measured per optically active foil, either at discrete wavelengths or in continuous wavelength spectra between 200 and 2700 nm.

10. A simulator device according to claim 1, wherein the control unit is configured for applying a periodic voltage to said at least one optically active foil, thereby modulating the absorption of light in the optically active layer with oscillations.

11. A simulator device according to claim 10, wherein the simulator device comprises a plurality of optically active foils and wherein the control unit is configured for applying a periodic voltage over at least one optically active foil of the plurality of active foils and further wherein the plurality of optically active foils comprises different optically active foils for absorption of different wavelengths.

12. A simulator device according to claim 1, wherein the at least one optically active foil comprises a dielectric medium sandwiched between two conductive layers, and wherein the transparency of the dielectric medium is dependent on the charge of the capacitor formed by the dielectric medium and the two conductive layers.

13. A simulator device according to claim 1, wherein the simulator device further comprises an internal reference sensor arranged for transmitting light into the at least one optically active layer and for measuring the light that is reflected back to and/or transmitted to the internal reference sensor.

14. A simulator device according to claim 1, wherein the control unit is further configured for synchronizing the voltage applied to the at least one active foil with an electrocardiogram (ECG) signal.

15. A method for calibrating a medical or non-medical device comprising the steps of a) providing a simulator device according to claim 1 and a medical or non-medical device to be calibrated; b) arranging the medical or non-medical device on the at least one skin-mimicking area; c) applying a voltage over at least one optically active foil; d) transmitting light from the medical or non-medical device into the skin-mimicking area and the at least one optically active foil; e) measuring the reflected light by said medical or non-medical device; and f) calibrating said medical or non-medical device using information from the measured reflected light.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0101] The above, as well as additional objects, features and advantages of the present inventive concept, will be better understood through the following illustrative and non-limiting detailed description, with reference to the appended drawings. In the drawings like reference numerals will be used for like elements unless stated otherwise.

[0102] FIG. 1 is a schematic illustration of an embodiment of a simulator device according to the present disclosure.

[0103] FIG. 2 is a section view of an embodiment of a simulator device according to the present disclosure.

[0104] FIG. 3 is a section view of an embodiment of an optically active foil.

[0105] FIG. 4 is a schematic illustration of the process step of a method of the present disclosure.

DETAILED DESCRIPTION

[0106] FIG. 1, and also FIG. 2, show an overall schematic embodiment of a simulator device 1 of the present disclosure. The simulator device 1 is for calibrating a medical or non-medical device 2, which for example be a pulse oximeter or a PPG device. The medical or non-medical device comprises in this example an SpO.sub.2 probe 2a for measuring the oxygen content in blood. The simulator device comprises a stack of optically active foils 3a-d. In this example, there are four foils 3a-d, but the simulator device 1 could comprise a single foil or at least 5 foils, such as at least ten optically active foils. On the uppermost optically active foil 3a, there are four skin-mimicking areas 4a-4d, each area representing a different skin tone. It is also to be understood that the simulator device 1 could comprise any number of skin-mimicking areas, such as at least five, such as at least ten skin-mimicking areas. As indicated in FIG. 1, the SpO.sub.2 probe 2a is placed on top of one or several of the skin-mimicking areas 4a-d during calibration.

[0107] The optically active foils 3a-d are used for e.g. simulating an oxygen content in the blood. To do this, the optically active foils 3a-d are configured for absorbing and reflecting light emitted by the SpO.sub.2 probe 2a during the calibration. The amount of absorption (and reflection) is controlled by a voltage applied to every optically active foil by a control unit 6. An optically active foil may thus comprise an LCD having a transparency dependent on the voltage applied over the LCD.

[0108] As indicated by arrows 11a-11c in FIG. 1, the control unit 6 is configured to control the voltage applied to each optically active foil independently. Thus, a first voltage may be applied to the uppermost foil 3a, a second voltage may be applied to the optically active foil 3b etc.

[0109] Furthermore, the simulator device comprises an optical feedback sensor 5a-d per optically active foil. Thus, there is one optical feedback sensor per optically active foil. This is further illustrated in the section view of FIG. 2. The feedback sensors 5a-d could thus be arranged within the stack of optically active foils 3a-d.

[0110] The optical feedback sensors 5a-d comprises in this example at least one photo-detector. The feedback sensors 5a-d are configured for measuring the optical response of each foil, i.e. feedback sensor 5a is configured for measuring the optical response of foil 3a, feedback sensor 5b is configured for measuring the optical response of foil 3b etc. The feedback sensors 5a-d and the control unit 6 are further configured for communicating with each other such that information of the optical response of each foil 3a-c is sent to control unit 6, as indicated by arrows 10a-d in FIG. 1. The control unit 6 is in this example wiredly connected to the feedback sensors 5a-d, but the wirelessly connected and to the feedback sensors 5a-d, e.g. if the feedback sensors 5a-d and the control unit 6 are connected to the same wireless communication network. The control unit is further configured to control the voltage applied to optically active foils 3a-d and for varying the applied voltage dependent on information from the optical feedback sensors 5a-d.

[0111] In this way, the memory effect of the LCD: s of the optically active foils may be reduced, i.e. the feedback control using the feedback sensors 5a-d and the control unit 6 allows for continuously controlling that the optically active foils functions properly. Consequently, the control unit 6 is further configured for controlling that the voltage applied to each optically active foil 3a-d produces the desired absorption of light each optically active foil 3a-d based on information on the measured absorption of light from the photo-detectors of the feedback sensors 5a-d. The measured absorption of light may then be compared to e.g. reference values, such as pre-defined reference values, and the control unit may be configured for adjusting an applied voltage if the measured absorption of light is outside a target range, or e.g. above or below a reference value. Hence, the control unit 6 may comprise a communication interface such as a transmitter/receiver, via which it may receive data from the feedback sensors. The control unit 6 is thus configured for receiving information from the feedback sensors 5a-d and for sending control voltages via lines 11a-d based on the received data.

[0112] The control unit 6 is further configured to carry out a method for assessing if an optical response of an optically active foil 3a-d is satisfactory, such as within a reference target range. For this purpose, the control unit 6 may comprise a device having processing capability in the form of processing unit, such as a central processing unit, which is configured to execute computer code instructions which for instance may be stored on a memory. The memory may thus form a computer-readable storage medium for storing such computer code instructions. The processing unit may alternatively be in the form of a hardware component, such as an application specific integrated circuit, a field-programmable gate array or the like.

[0113] The control unit 6 may also be configured for controlling when to take measurements with the optical feedback sensors, i.e. if measurements are to be taken continuously or at discrete time points. Thus, the control unit 6 may further be configured for controlling the initiation of the measuring of optical response using the feedback sensors 5a-d. For this purpose, the processing unit of the control unit 6 may further comprise computer code instructions for sending operational requests to the optical feedback sensors 5a-d.

[0114] The system 1 may further comprise display means connected to the control unit 6 for displaying on a screen one or several optical responses measured by the feedback sensors 5a-d.

[0115] As an alternative, the control unit 6 may be configured just for receiving the data from the feedback sensors 5a-d. This data may then be sent to an external unit for further processing. As an example, the data may be transmitted to a storage unit (not shown), which may be a disk drive of a computer. A communication interface of the control unit 6 may thus be configured to transmit received data from feedback sensors 5a-d to a remote storage unit, such as a cloud-based storage unit. A remote software may then be used for assessing the optical response of the optically active foils 3a-d. Consequently, the data received by the control unit 6 may be sent to a computer, and such a computer may have a central processing unit (CPU) and may further be provided with a software for causing the CPU to perform operations so as to determine if the optical response of the foils 3a-d are satisfactory, such as within a certain target range.

[0116] The control unit 6 is in this example further configured for reversing the polarity of the voltage applied to the optically active foils 3a-d if the desired absorption of light in the optically active foils is not satisfactory, such as outside an absorption target range. This may aid in decreasing the risk of memory effect even further.

[0117] The foils 3a-d are configured for absorbing different wavelengths of light. As an example, one of the foils 3a-d may be configured for absorbing a first wavelength about 660 nm, whereas another foil may be configured for absorbing a second wavelength of about 940 nm.

[0118] Furthermore, the control unit 6 is in this example configured for applying a periodic voltage to one of the optically active foils 3a-d, thereby modulating the absorption of light in the optically active layer with oscillations. As an example, the control unit 6 may be configured to provide a periodic voltage to the uppermost foil 3a.

[0119] The absorption properties of the foils 3a-d make it possible to simulate different oxygenation in blood vessels, and the oscillating behaviour of the uppermost foil makes it possible to simulated dynamic variations in the absorption, such as variations depending on heart rate etc. Thus, the simulator device 1 is able to include respiration-induced amplitude variations of the heart beat (PPG waves) with precise synchronization to the respiration cycle.

[0120] Furthermore, the earth may be common to all the optically active layers. It may be advantageous to have the foil, which is producing the PPG signals (white), being the most external one 3a. In this way, the earth will always be the most external layer and the electrical influence of the foils 3a-d into the probe will be greatly attenuated.

[0121] The medical or non-medical device 2 comprising the SpO2-probe 2a may determine an SpO2 value by calculating the ratio of the absorption of light in two know wavelengths, such as 660 nm and 940 nm. To calculate this ratio, the pulsation of the light intensity due to the modulation of the blood volume using the periodic voltage may be a key factor.

[0122] To decrease the value of the calculated oxygen, the absorption of red light may be decreased in comparison to the IR light. Therefore, the light intensity of the red light, will decrease when the SpO2 is increasing.

[0123] Consequently, during calibration, the probe 2a of the medical or non-medical device 2 under test (pulse oximeter or multiparameter monitor) is placed upon the chosen skin type and collects the simulated optical signals.

[0124] As also seen in FIG. 1, the simulator device 1 comprises an internal reference sensor 8 arranged for transmitting light into the optically active layers 3a-d and for measuring the light that is reflected back to the internal reference sensor 8. This information is also sent to control unit 6 as indicted by arrow 8a in FIG. 1. This internal reference sensor 8 allows for (more input on why internal reference sensor 8 is used). The reference sensor 8 could be arranged on top one of the skin-mimicking areas 4a-d, or it could be arranged within any of the optically active foils 3a-d.

[0125] There is further an ECG unit 7 configured for simulating an ECG (electrocardiography) signal and for sending this to the control unit 6, as indicated by arrow 7a in FIG. 1. The control unit 6 is then configured for synchronizing the voltage applied to the optically active foils 3a-d with the received ECG signal.

[0126] The ECG unit 1 may be part of the simulator device 1 or be an external unit.

[0127] Furthermore, the control unit may also comprise software that generates a photoplethysmographic (PPG) waveform plus synchronized ECG at a chosen heart rate. As an alternative, the control unit 6 may be configured to receive a signal from e.g. a computer comprising a control software for generating generates a photoplethysmographic (PPG) waveform plus synchronized ECG at a chosen heart rate. The simulator device 1 is thus capable of being synchronized to an electrical electrocardiogram (ECG) signal as well-known in the art of ECG patient simulators. Furthermore, the simulator device 1 allows to vary the time between an ECG R-wave and the PPG wave in a very precise and reproducible manner. The travelling speed of the mechanical arterial Pulse Wave (which can be detected by PPG) is blood pressure dependent. The simulator device 1 may thus aid in developing non-invasive blood pressure monitoring without the need for frequent pressurizing a pneumatic cuff (which present blood pressure measurement devices require).

[0128] FIG. 3 is a schematic section view of one of the optically active foils 3a. The foils 3a comprises a dielectric medium 12 sandwiched between two conductive layers 13a and 13b. The transparency of the dielectric medium 12 is dependent on the charge of the capacitor formed by the dielectric medium 12 and the two conductive layers 13a and 13b, i.e. on the voltage applied over the foil 3a.

[0129] FIG. 4 schematically illustrates a method 100 for calibrating a medical or non-medical device 2 using the simulator device of the present disclosure. The method comprises the steps of [0130] a) providing 101 a simulator device 1 as disclosed herein and a medical or non-medical device 2 to be calibrated; [0131] b) arranging 102 the medical or non-medical device 2 on at least one skin-mimicking area 4a-d; [0132] c) applying 103 a voltage over at least one optically active foil 3a-d; [0133] d) transmitting 104 light from the medical or non-medical device 2 into the skin-mimicking area 4a-d and the at least one optically active foil 3a-d; [0134] e) measuring 105 the reflected light by the medical or non-medical device 2; and [0135] f) calibrating 106 the medical or non-medical device 2 using information from the measured reflected light.

[0136] The medical or non-medical device 2 to be calibrated usually transmits light of two colours, 660 nm and 940 nm. Depending on the intensity of each detected wavelength, the device 2 is able to determine the amount of light absorbed of each colour. This absorption information can be processed and calibrated to give values of instantaneous arterial oxygen saturation. With the simulator device 1, the voltage of one active foil 1 is modulated with a periodic input signal to modulate the absorption with PPG like oscillations, since also a person's body onto which the medical or non-medical device is to be used pulsates (with PPG like signals). On top of that the voltage of the rest of optically active foils 3a are modulated such that the absorption of each wavelength is modulated. Ion this way, the simulator device 1 produces the same absorption the body produces with different values of oxygen.

[0137] As discussed above, the feedback sensors 5a-d is measuring continuously, such that the control unit 6 is continuously controlling that the applied voltage is actually producing the desired SpO2 value, i.e. the control unit 6 controls that the voltage is producing the desired absorption for each light.

[0138] Thus, the method may also comprise a step of controlling that the voltage applied to the optically active foils (3a-d) produces the desired absorption of light in the at least one optically active foil (3a-d) based on information on the measured absorption of light from at least one photo-detector in a feedback sensor. The method may then comprise adjusting the applied voltage if the measured absorption of light is outside an absorption target range.

[0139] Furthermore, the method may comprise the step of reversing the polarity of the voltage applied to optically active foils 3a-d if the desired absorption of light in the optically active foils 3a-d is outside a target range, such as a reference interval.

[0140] Since the memory effect is quite unpredictable, it may be required to have a control on each of the optically active foils 3a-d individually and also the internal reference sensor 8. This internal reference sensor 8 may be a well calibrated sensor, with better signal-to-noise ratio than the sensor 2a of the medical or non-medical device 2.

[0141] The simulator device 1 may thus be a reflective simulator. It is an advantage of having a reflective simulator that does not receive and emit modulated light to emulate values of oxygen or PPG waveforms. The changes in the detected light by the medical or non-medical device 2 when calibrated in a reflective simulator are changes in absorption which leaves the timing and wavelengths of the photons unaltered. This in combination with the programmable ECG gives the possibility of testing Pulse arrival time, in an unprecedented way, e.g. to test the stability a medical or non-medical device 2 at different temperatures.

[0142] In the above the inventive concept has mainly been described with reference to a limited number of examples. However, as is readily appreciated by a person skilled in the art, other examples than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended claims.