Multi-channel optical pressure sensor

Abstract

A multi-channel optical pressure sensor is provided. The multi-channel optical pressure sensor includes at least one LED configured to generate light having a first spectrum and a second spectrum, a plurality of sensors including a first sensor coupled to the at least one LED via at least one first optical fiber and a second sensor coupled to the at least one LED via at least one second optical fiber, and a detector module coupled to the first sensor and the second sensor. The detector module includes at least one lens and an image sensor configured to detect light received from the at least one lens.

Description

Technical Field

[0001] Field of the Invention The present disclosure relates to a multi-channel optical pressure sensor.

Background Art

[0002] Background Fluid pumps, such as blood pumps, are used in the medical field for a wide range of applications and purposes. An intravascular blood pump is a pump that can be advanced through a patient's vascular system, i.e., veins and / or arteries, to a location within the patient's heart or to other locations within the patient's circulatory system. For example, an intravascular blood pump can be inserted via a catheter and positioned to reach a heart valve. An intravascular blood pump is typically disposed at the end of a catheter. Once in the appropriate position, the pump can be used to assist the heart, pump blood through the circulatory system, and thus temporarily reduce the workload of the patient's heart, for example, to allow the heart to recover after a heart attack. An exemplary intravascular blood pump is available from ABIOMED, Inc., Danvers, MA under the trademark name Impella® Heart Pump.

[0003] Such a pump can be positioned, for example, within a ventricle such as the left ventricle to assist the heart. In this case, the blood pump can be inserted via a femoral artery by a hollow catheter and introduced into and into the left ventricle of the patient's heart. From this position, the blood pump inlet draws in blood and the blood pump outlet discharges the blood into the aorta. In this way, the function of the heart can be replaced or at least assisted by the operation of the pump.

[0004] An intravascular blood pump is typically connected to respective external heart pump controllers, each of which controls the heart pump, such as motor speed, and collects and displays operating data about the blood pump, such as heart signal level, battery temperature, blood flow rate, and plumbing integrity. An exemplary heart pump controller is available from Abiomed, Inc. under the trademark name Automated Impella Controller®. The controller issues an alarm when an operating data value is outside a predetermined value or range, for example, when a leak, suction, and / or malfunction of the pump is detected. The controller may include a video display screen on which a graphical user interface configured to display the operating data and / or the alarm is presented. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0005] Overview Described herein are systems and methods for a multi-channel optical pressure sensor. The multi-channel optical pressure sensor can be incorporated into a heart pump in some embodiments. When incorporated into the heart pump, the multi-channel optical pressure sensor can be used to detect, for example, a differential pressure across the aortic valve when the heart pump is positioned within a patient's heart. Differential pressure measurements can be used, for example, to calculate the blood flow rate through the heart pump during its operation.

[0006] In some embodiments, a multi-channel optical pressure sensor is provided. The multi-channel optical sensor includes at least one light emitting diode (LED), a plurality of sensors including a first sensor coupled to the at least one LED via at least one first optical fiber and a second sensor coupled to the at least one LED via at least one second optical fiber, and a detector module coupled to the first sensor and the second sensor, the detector module including at least one lens and an image sensor configured to detect light received from the at least one lens, and at least one hardware processor configured to determine a first pressure measured by the first sensor and a second pressure measured by the second sensor based at least in part on the light detected by the image sensor.

[0007] On one side, the at least one LED includes a first LED configured to generate first light having a first spectrum and a second LED configured to generate second light having a second spectrum. On one side, the first spectrum has a peak wavelength in the range of 550 - 670 nm, and the second spectrum has a peak wavelength in the range of 800 - 900 nm. On one side, the first spectrum has a peak wavelength in the range of 550 - 600 nm. On one side, the first spectrum has a peak wavelength that is 4 / 5 of the peak wavelength of the second spectrum. On one side, the first LED and / or the second LED is smaller than 1 mm. On one side, the first LED and / or the second LED is a phosphor-converted LED. On one side, the at least one LED includes a single LED having a broad spectrum.

[0008] On one side, the sensor further includes a first optical element arranged between at least one LED and a plurality of sensors. The first optical element is configured to receive a first light and a second light, and output a third light and a fourth light, each of the third light and the fourth light having a third spectrum. On one side, the sensor further includes a second optical element coupled to the first optical element, the first sensor, and the detector module, and a third optical element coupled to the first optical element, the second sensor, and the detector module. On one side, the second optical element is configured to provide a first reflected light from the first sensor to the detector module, and the third optical element is configured to provide a second reflected light from the second sensor to the detector module.

[0009] On one side, at least one lens is a plano lens. On one side, the plano lens includes a set of D-shaped lenses having curved edges facing each other. On one side, at least one lens is configured to reduce spherical aberration in the light received from the first sensor and the second sensor. On one side, at least one lens is configured to expand the incidence of the optical signal on at least one lens. On one side, the expansion factor of at least one lens is at least 1.1 and less than 3. On one side, the expansion factor is at least 1.1 and less than 2. On one side, the expansion factor is less than 1.5. On one side, the expansion factor is less than 1.3. On one side, at least one lens includes at least two lenses that collectively expand the incidence of the optical signal on at least one lens. On one side, the at least two lenses include a first lens having a first focal length and a second lens having a second focal length different from the first focal length. On one side, each of the first lens and the second lens is a D-shaped lens having a curved edge, and the curved edges of the first lens and the second lens are arranged to face each other.

[0010] On one side, the detector module further includes a Fizeau arranged between at least one lens and the image sensor. On one side, the image sensor includes a two-dimensional image sensor. On one side, at least one lens and the Fizeau are configured to collectively project the light received from the first sensor and the second sensor as two lines on the two-dimensional image sensor. On one side, the two lines are two parallel lines. On one side, each of the two lines on the two-dimensional image sensor includes an interferogram, and determining the first pressure measured by the first sensor and the second pressure measured by the second sensor based at least in part on the light detected by the image sensor includes determining the first pressure and the second pressure based on the corresponding interferogram.

[0011] In some embodiments, a circulatory support device is provided. The circulatory support device includes a rotor, a motor configured to drive the rotation of the rotor at one or more speeds, a first optical pressure sensor configured to detect a first pressure signal, a second optical pressure sensor configured to detect a second pressure signal, and at least one hardware processor. The at least one hardware processor is configured to determine a differential pressure signal based at least in part on the first pressure signal and the second pressure signal.

[0012] In one aspect, at least one hardware processor is further configured to determine a flow rate through a circulatory assist device based at least in part on a differential pressure signal. In one aspect, the circulatory assist device further includes a first light emitting diode (LED) coupled to a first optical pressure sensor and a second optical pressure sensor, the first LED being configured to generate first light having a first spectrum, a second LED coupled to the first optical pressure sensor and the second optical pressure sensor, the second LED being configured to generate second light having a second spectrum. In one aspect, the first spectrum has a peak wavelength in the range of 550-670 nm and the second spectrum has a peak wavelength in the range of 800-900 nm. In one aspect, the first spectrum has a peak wavelength in the range of 550-600 nm. In one aspect, the first spectrum has a peak wavelength that is 4 / 5 of the peak wavelength of the second spectrum. In one aspect, the first LED and / or the second LED is smaller than 1 mm. In one aspect, the first LED and / or the second LED is a phosphor-converted LED.

[0013] On one side, the circulation support device further includes a first optical element, and the first optical element is configured to receive the first light and the second light and output a third light and a fourth light, each of the third lights having a third spectrum, the third light being provided to the first optical pressure sensor, and the fourth light being provided to the second optical pressure sensor. On one side, the circulation support device further includes a second optical element coupled to the first optical element and the first optical pressure sensor, and a third optical element coupled to the first optical element and the second optical pressure sensor. On one side, the circulation support device further includes a detector module, the second optical element is configured to provide a first reflected light from the first optical pressure sensor to the detector module, and the third optical element is configured to provide a second reflected light from the second optical pressure sensor to the detector module.

[0014] In one aspect, the circulation assistance device further includes a detector module coupled to a first optical pressure sensor and a second optical pressure sensor. The detector module includes at least one lens and an image sensor configured to detect light received from the at least one lens. In one aspect, the at least one lens includes a plano lens. In one aspect, the plano lens includes a set of D-shaped lenses having curved edges facing each other. In one aspect, the at least one lens is configured to reduce spherical aberration in the light received from the first optical pressure sensor and the second optical pressure sensor. In one aspect, the at least one lens is configured to expand the incidence of the optical signal on the at least one lens. In one aspect, the expansion factor of the at least one lens is at least 1.1 and less than 3. In one aspect, the expansion factor is at least 1.1 and less than 2. In one aspect, the expansion factor is less than 1.5. In one aspect, the expansion factor is less than 1.3. In one aspect, the at least one lens includes at least two lenses that collectively expand the incidence of the optical signal on the at least one lens. In one aspect, the at least two lenses include a first lens having a first focal length and a second lens having a second focal length different from the first focal length. In one aspect, each of the first lens and the second lens is a D-shaped lens having a curved edge, and the curved edges of the first lens and the second lens are arranged to face each other.

[0015] On one side, the detector module further includes a Fizeau arranged between at least one lens and an image sensor. On one side, the image sensor includes a two-dimensional image sensor. On one side, at least one lens and the Fizeau are configured to collectively project the light received from the first optical pressure sensor and the second optical pressure sensor as two lines on the two-dimensional image sensor. On one side, the two lines are two parallel lines. On one side, each of the two lines on the two-dimensional image sensor includes an interferogram, and at least one hardware processor is configured to determine the first pressure and the second pressure based on the corresponding interferogram, thereby determining, at least partially based on the light detected by the image sensor, the first pressure measured by the first optical pressure sensor and the second pressure measured by the second optical pressure sensor. Determining the differential pressure signal based at least in part on the first pressure signal and the second pressure signal includes determining the differential pressure signal based on the first pressure and the second pressure.

Brief Description of the Drawings

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Figure 1A

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Figure 1B

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Figure 1C

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Figure 6A

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Figure 6B

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Figure 6C

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Figure 8B

[0029] Detailed Description A circulatory support device (also referred to herein as a "heart pump" or simply a "pump") can include a percutaneous catheter-based device that provides hemodynamic support to a patient's heart. As will be appreciated, for the heart pump to function properly, its inlet portion should be positioned within the left ventricle and its outlet portion should be positioned within the aorta, such that it is correctly positioned within the patient's heart in a state that reaches the aortic valve of the patient's heart. As shown in FIG. 1A, the heart pump 110 can include a pigtail 111, an inlet area 112, a cannula 113, a pressure sensor 114, an outlet area 115, a motor housing 116, and / or a catheter tube 117. The pigtail 111 can assist in stabilizing the heart pump 110 within the patient's heart. It should be understood that some embodiments of the heart pump 110 may not include the pigtail 111, and the heart pump 110 may be stabilized in other ways or may not be stabilized at all. During operation, blood can be drawn into one or more openings in the inlet area 112 by a motor (not shown) disposed within the motor housing 116, conducted through the cannula 113, and discharged through one or more openings in the outlet area 115. In some implementations, the pressure sensor 114 can include a flexible membrane integrated with the cannula 113. One side of the pressure sensor 114 can be exposed to the blood pressure on the outside of the cannula 113, and the other side can be exposed to the pressure of the blood inside the cannula 113. In some such implementations, the pressure sensor 114 can generate an electrical signal proportional to the difference between the pressure outside the cannula 113 and the pressure inside the cannula 113. In some implementations, the pressure sensor 114 can include an optical pressure sensor. The catheter tube 117 can provide one or more fluid and / or electrical connections between the heart pump 110 and one or more other devices of the ventricular support system, an example of which is shown in FIG. 1C.

[0030] As shown in FIG. 1B, the heart pump 110 can be positioned within the patient's heart 120. For example, the heart pump 110 can be inserted percutaneously through the femoral artery 122 into the ascending aorta 124, traverse the aortic valve 126, and be inserted into the left ventricle 128. In other implementations, the heart pump can be inserted percutaneously through the axillary artery 123 into the ascending aorta 124, traverse the aortic valve 126, and be inserted into the left ventricle 128, for example. In other implementations, the heart pump can be inserted directly into the ascending aorta 124, traverse the aortic valve 126, and be inserted into the left ventricle 128, for example. During operation, the heart pump 110 can take in blood from the left ventricle 128 and discharge the blood into the ascending aorta 124. As a result, the blood pump 110 can perform a part of the work normally performed by the patient's heart 120. The hemodynamic effects of the heart pump can include an increase in cardiac output and an improvement in coronary blood flow that results in a decrease in left ventricular end-diastolic pressure, pulmonary capillary wedge pressure, myocardial work, and oxygen consumption.

[0031] As shown in FIG. 1C, the heart pump 110 may form part of a ventricular assist system 100. The ventricular assist system 100 may also include a controller 130 (e.g., an Automated Impella Controller (registered trademark), referred to herein as "AIC" from ABIOMED, Inc. (Danvers, Mass.)), a display 140, a purge subsystem 150, a connector cable 160, a plug 170, and a repositioning unit 180. As shown, the controller 130 may include the display 140. The controller 130 monitors and controls the operation of the heart pump 110. During operation, the purge subsystem 150 may be configured to deliver a purge fluid to the heart pump 110 through the catheter tube 117 to prevent blood from entering a motor (not shown) within the motor housing 116. In some implementations, the purge fluid is a glucose solution (e.g., 5% dextrose with 25 IU / mL or 50 IU / mL of heparin). The connector cable 160 may provide an electrical connection between the heart pump 110 and the controller 130. The plug 170 connects the catheter tube 117, the purge subsystem 150, and the connector cable 160. In some implementations, the plug 170 includes a storage device (e.g., a memory) configured to store, for example, operating parameters to facilitate the transfer of the patient to another controller, if required. The repositioning unit 180 may be used to reposition the heart pump 110 within the patient's heart.

[0032] As shown, in some embodiments, the ventricular assist system may include a purge subsystem 150, which has a container 151, a supply line 152, a purge cassette 153, a purge disk 154, purge tubing 155, a check valve 156, a pressure reservoir 157, an infusion filter 158, and a side arm 159. The container 151 can be, for example, a bag or a bottle. As will be appreciated, in other embodiments, the ventricular assist system may not include a purge subsystem. In some embodiments, the purge fluid may be stored in the container 151. The supply line 152 can provide a fluid connection between the container 151 and the purge cassette 153. The purge cassette 153 can control how the purge fluid in the container 151 is delivered to the heart pump 110. For example, the purge cassette 153 may include one or more valves for controlling the pressure and / or flow rate of the purge fluid. The purge disk 154 may include one or more pressure and / or flow sensors for measuring the pressure and / or flow rate of the purge fluid. As shown, the controller 130 may include the purge cassette 153 and the purge disk 154. The purge tubing 155 can provide a fluid connection between the purge disk 154 and the check valve 156. The pressure reservoir 157 provides an additional filling volume during purge fluid exchange. In some implementations, the pressure reservoir 157 includes a flexible rubber diaphragm that provides an additional filling volume by means of an expansion chamber. The infusion filter 158 helps prevent bacterial contamination and air from entering the catheter tube 117. The side arm 159 provides a fluid connection between the infusion filter 158 and the plug 170.

[0033] Although shown as having separate purge tubing and connector cables, it will be appreciated that in some embodiments, the ventricular assist system may include a single connector with both a fluid line and an electrical line connectable to the AIC.

[0034] During operation, the controller 130 can be configured to receive measurements from the pressure sensor 114 and the purge disk 154 and control the operation of a motor (not shown) within the motor housing 116 and the purge cassette 153. As described above, the controller 130 can be configured to control and measure the pressure and / or flow rate of the purge fluid via the purge cassette 153 and the purge disk 154. During operation, after exiting the purge subsystem 150 through the side arm 159, the purge fluid can be directed through the catheter tube 117 and a purge lumen (not shown) within the plug 170. The sensor cable (not shown) within the catheter tube 117, the connector cable 160, and the plug 170 can provide an electrical connection between the pressure sensor 114 and the controller 130. The motor cable (not shown) within the catheter tube 117, the connector cable 160, and the plug 170 can provide an electrical connection between the motor within the motor housing 116 and the controller 130. During operation, the controller 130 can be configured to receive measurements from the pressure sensor 114 through a sensor cable (e.g., an optical fiber) and control the power delivered to the motor within the motor housing 116 through the motor cable. By controlling the power delivered to the motor within the motor housing 116, the controller 130 can be operative to control the speed of the motor within the motor housing 116.

[0035] Various modifications can be made to the ventricular assist system 100 and one or more of its components. For example, one or more additional sensors can be added to the heart pump 100. In another example, a signal generator can be added to the heart pump 100 to generate a signal indicative of the rotational speed of the motor within the motor housing 116. As another example, one or more components of the ventricular assist system 100 can be separated. For example, the display 140 can be incorporated into another device that communicates with the controller 130 (e.g., wirelessly or through one or more electrical cables).

[0036] As described herein, a heart pump (e.g., heart pump 110) may include a pressure sensor 114 (e.g., an optical pressure sensor) configured to detect the pressure within the aorta of a patient's heart when the heart pump is properly positioned. The pressure signal detected by the pressure sensor 114 may be used, at least in part, to determine the accurate positioning of the heart pump within the patient's heart and / or to determine the blood flow rate through the heart pump when it is in operation. For example, the pressure signal may be used in combination with a set of motor current signals received from a motor current sensor (not shown) and stored values to determine the flow rate through the heart pump. The differential pressure across the aortic valve may also be determined indirectly based on a combination of the pressure signal measuring the pressure in the aorta and stored values.

[0037] The inventors have recognized and understood that, rather than having to infer the pressure in the left ventricle based on a pressure sensor signal detected in the aorta as described above, it may be useful to incorporate one or more additional pressure sensors within the heart pump 110, for example, to directly detect the pressure in both the aorta and the left ventricle. The use of multiple pressure sensors is also referred to herein as implementing a multi-channel pressure sensor. FIG. 2 illustrates an embodiment of a heart pump 200 in which a second pressure sensor 210 is arranged near the inlet area 112. When properly positioned within the patient's heart, the second pressure sensor 210 may be configured to measure a pressure sensor signal used to determine the left ventricular blood pressure. In such an implementation, an additional sensor cable (e.g., an optical fiber) may be disposed within the catheter tube 117 to provide a connection between the second pressure sensor 210 and a controller (e.g., controller 130).

[0038] The inventors recognized and understood that it may be useful to provide a sensor that is lower power and / or smaller than some of the pressure sensors (e.g., including pressure sensor 114) used in some conventional heart pumps for housing a plurality of pressure sensors within a heart pump. Additionally, optically-based pressure sensors may have advantages over electronic or other types of pressure sensors, including, but not limited to, their smaller size, their small or negligible pressure drift, and their durability. FIG. 3 schematically illustrates a multi-channel pressure sensor system 300 designed in accordance with some embodiments of the present technology. System 300 includes a light source 310 and a plurality of optical sensors (e.g., first sensor 340 and second sensor 360) coupled via an optical fiber and one or more optical elements. In an exemplary system 300, the light source 310 includes two light-emitting diodes (LEDs) (i.e., first LED 312 and second LED 314) configured to output light with different spectra. As described in more detail below, the spectra of the light output from the first LED 312 and the second LED 314 may be selected such that their combined output has some characteristics similar to white light generated, for example, by a tungsten lamp. In some embodiments, the size of the LED may be less than 1 millimeter. Such characteristics may facilitate the use of a low-power LED light source for implementing multi-channel optical pressure sensing in a heart pump in accordance with the techniques described herein.

[0039] As shown, system 300 includes a plurality of optical elements arranged between a light source 310 and a plurality of sensors (e.g., sensor 340, sensor 360). The first optical element 320 is arranged to receive light from the first LED 312 and the second LED 314. In some embodiments, the first optical element 320 is implemented as a splitter that mixes the light from the first LED 312 and the second LED 314 and provides light to the second optical element 330 and the third optical element 350 at its output. The light provided as an input to the second optical element 330 and the third optical element 350 may have a spectrum that is blended or "mixed" from the light output from the first LED 312 and the second LED 314 and may have half the power of the light provided from the light source 310 as an input to the first optical element 320. By mixing the light from the first LED 312 and the second LED 314, the first optical element provides light with a spectrum that has some characteristics in common with the white light that could be produced using a less efficient (e.g., tungsten-based) light source. It should be understood that other types of light sources and / or optical components may be used instead to generate light for use with some embodiments. For example, a single low-power light source 310 configured to generate light having a plurality of spectra or a complex spectrum having some characteristics in common with white light (e.g., light with a broad spectrum such as an ultra-wide area LED) may be used instead. In such embodiments, the first optical element 320 configured to mix the light from a plurality of light sources (e.g., LED 312 and LED 314) may not be required, and the light output from a single light source may be provided directly to the second optical element 330 and the third optical element 350 via one or more optical fibers.

[0040] In some embodiments, the second optical element 330 can be implemented as a splitter that provides the mixed spectral light output from the first optical element 320 to the first sensor 340. The first sensor 340 can be configured as a reflective element such that at least a portion of the light provided to the first sensor 340 is reflected back through the second optical element 330, and the second optical element 330 provides the reflected light as an input to the detector module 370. Similarly, the third optical element 350 can be configured as a splitter that provides the mixed spectral light output from the first optical element 320 to the second sensor 360. The second sensor 360 can be configured as a reflective element such that at least a portion of the light provided to the second sensor 360 is reflected back through the third optical element 350, and the third optical element 350 provides the reflected light as an input to the detector module 370. In this way, the reflected light signals provided by the first sensor 340 and the second sensor 360 are further processed by components of the detector module 370. In some embodiments, the first optical fiber coupled between the second optical element 330 and the detector module 370 and the second optical fiber coupled between the third optical element 350 and the detector module 370 can be coupled to the detector module 370 via a connector configured to arrange the first optical fiber and the second optical fiber very close to each other.

[0041] As shown, detector module 370 may include one or more lenses 372 (e.g., plano lens, aspherical lens, biconvex lens, etc.), a Fabry - Perot 374, and an image sensor 376. In some embodiments, lens 372 may be implemented as a set of facing D - shaped lenses, as described in more detail herein. In some embodiments, lens 372 may be configured to provide magnification to the optical signal transmitted through lens 372. In some embodiments, the magnification may be provided by implementing lens 372 as a set of facing asymmetric D - shaped lenses, as described in more detail herein. Lens 372 may be used to reduce spherical aberration, thereby allowing multiple channels of light reflected from the sensor to be spatially separated and represented on the detector as two (or more) parallel or nearly parallel lines, with limited crosstalk between them. The light received by lens 372 is provided as an input to Fabry - Perot 374. Fabry - Perot 374 may be implemented as two mirrors with a spatially varying dielectric layer arranged between them. The light entering Fabry - Perot 374 may resonate at specific locations on the spatially varying dielectric layer to create light rays that are captured by detector 376, as shown, for example, in FIG. 7A. In some embodiments, image sensor 376 may be configured as a two - dimensional image sensor in which light from multiple channels is detected corresponding to the interferogram of the reflected optical signals from the first sensor 340 and the second sensor 360. System 300 may further include at least one hardware processor 380 configured to analyze the signals captured by image sensor 376 to determine the pressure sensed by each of the first sensor 340 and the second sensor 360 based on, for example, the interferogram signal captured by image sensor 376. In some embodiments, at least one hardware processor 380 may be implemented as part of the controller 130 described above in connection with FIG. 1C.

[0042] FIG. 4 schematically illustrates an arrangement of components of a detector module 370 according to some embodiments. As shown, the detector module 370 includes a connector 410 configured to receive optical fibers from a second optical element 330 and a third optical element 350 as described above in connection with FIG. 3. The connector 410 may be configured to arrange the incoming optical fibers in close proximity to each other. Two light rays output from the connector 410 are provided to a lens 372 to focus the light on a Fresnel 374, which redirects the light onto the surface of an image sensor 376. In some embodiments, the connector 410 is movable in a plane parallel to the lens 372 to adjust the focus of the light rays on the image sensor 376. As shown, the lens 372 may be implemented as a set of D-shaped lenses having their curved edges facing each other. The lens 372 may be configured to reduce spherical aberration, which would be present if, for example, rod lenses were used.

[0043] FIG. 5 schematically illustrates a process for performing interferometry using an optical system, such as the optical system described herein. In the example of FIG. 5, a white light source (e.g., a tungsten lamp) is used as the light source (e.g., light source 310 in FIG. 3). However, as will be appreciated, other light sources (e.g., LEDs 312, 314) may be used instead. As shown, the light generated by the light source is provided as incident light I0 to a sensor (e.g., sensor 340 or sensor 360 in FIG. 3) through an optical fiber. As shown, the sensor may be implemented as a transducer for detecting an interferometer. The reflected light I r is provided to a detector module (e.g., detector module 370) including an optical wedge (e.g., Fresnel 374) for generating an interferogram signal (e.g., on an image sensor 376). The central peak of the interferogram signal may be tracked and / or otherwise used to determine the pressure value detected by the sensor.

[0044] As described herein, the inventors recognized and understood that some conventional white light sources generate a significant amount of heat, consume a large amount of power, which limits their use in certain implementations, including as a light source for a multi-channel optical pressure sensor in a heart pump. Thus, in some embodiments, one or more low power light sources can be used to provide light having some characteristics similar to a white light source. For example, as described above in connection with system 300 shown in FIG. 3, two LED sources configured to generate light having different spectra can be used.

[0045] FIG. 6A shows a plot of the spectrum of light output by a white light source (upper plot) and the corresponding interferogram signal (lower plot) recorded using the white light source. As shown, a conventional white light source has a broadband spectrum, which results in an interferogram signal with a distinct central region with small side lobes. Such an interferogram signal is ideal for determining the pressure sensed by a combined optical pressure sensor. FIG. 6B shows a plot of the spectra of light output by two narrowband LED light sources (upper plot) and the corresponding interferogram signal (lower plot) recorded using the two LED light sources. The spectrum of the light generated by the first LED light source can have a shorter peak wavelength (e.g., in the range of 550 nm to 650 nm), and the spectrum of the light generated by the second LED light source can have a longer peak wavelength (e.g., in the range of 800 nm to 900 nm). In some embodiments, the spectrum of the light generated by the first LED light source has a peak wavelength in the range of 550 nm to 610 nm, and the spectrum of the light generated by the second LED light source has a peak wavelength in the range of 820 nm to 850 nm. In some embodiments, the peak wavelength of the first LED light source is 4 / 5 of the peak wavelength of the second LED light source.

[0046] As shown in the lower plot of FIG. 6B, the interferogram signal generated using two narrow-band LED light sources has several features similar to the interferogram signal generated using the broadband white light source shown in FIG. 6A. For example, the interferogram signal shown in FIG. 6B has a central portion similar to the central portion of the interferogram signal shown in FIG. 6A and a lateral envelope that distinguishes the central region from the other parts of the signal. When the lateral envelope near the central portion of the signal is sufficiently reduced to enable tracking of the central portion of the signal relative to the other parts of the signal, the interferogram signal shown in FIG. 6B can be used in a manner similar to the interferogram signal shown in FIG. 6A and described above in connection with the process shown in FIG. 5. FIG. 6C illustrates an interferogram generated by two LEDs having a wider spectrum. As shown in the lower plot of FIG. 6C, the interferogram signal generated by two broad-spectrum LED light sources is closer to the interferogram generated by a tungsten lamp. In some embodiments, the lateral envelope of the interferogram signal can be significantly attenuated. Thus, some embodiments mimic the use of a broadband white light source by using a plurality of narrow-band and power-saving LED light sources, and the plurality of narrow-band and power-saving LED light sources, when used in combination, generate an interferogram signal that can be used in a multi-channel optical pressure sensor (e.g., for a heart pump). In some embodiments, one or more features (e.g., amplitude, position) of the central peak of the central portion of the interferogram signal can be used to determine the pressure value detected by the corresponding pressure sensor associated with the interferogram signal. It should be understood that in some embodiments, more than two light sources (e.g., LEDs) can be used and the embodiments are not limited in this regard.Accordingly, a 2-channel optical pressure sensor system is shown and described herein, although any multi-channel (e.g., two or more channels) optical pressure sensor system can be implemented using techniques similar to those described herein. More than two light sources may be beneficial in embodiments where more than two channels are used such that the power of the optical signals provided to each of the sensors is sufficient to generate a reliable interferogram signal.

[0047] FIG. 7A illustrates a display of an image representing an interferogram signal captured by a two-dimensional image sensor (e.g., image sensor 376 shown in FIG. 3) according to some embodiments. As shown, the interferogram signals captured by the image sensor for each of the corresponding optical sensors are represented as lines. For example, a first interferogram signal corresponding to the reflected light from sensor 340 may be represented as line 710, and a second interferogram signal corresponding to the reflected light from sensor 360 may be represented as line 720. As described herein, the components of the detector module may enable the interferogram signals represented as lines 710 and 720 to be spatially distinguishable and separable (e.g., without crosstalk or with limited crosstalk). Only a very small portion of the image sensor shown in FIG. 7A is shown as being utilized, and it should be understood that the feasibility of using more than two channels according to the techniques described herein (if desired) is demonstrated. For example, in some embodiments, up to 6 channels, 8 channels, or 10 channels may be used. The intensity of the interferogram signal can be extracted from the captured image sensor signal into the interferogram signal as shown in FIG. 7B. As described above, based at least in part on the extracted interferogram signal, the pressure sensed by the corresponding sensor can be determined.

[0048] FIG. 8A schematically illustrates components of a detector module that can be used to detect an interferogram signal associated with an optical pressure sensor according to some embodiments. Similar to the detector module 370 shown in FIG. 4, the detector module shown in FIG. 8A can include a lens 372 configured to receive one or more light rays from an optical connector 410 (e.g., two light rays related to the dual optical channel detector design shown in FIG. 4). The lens 372 can be configured to focus the light onto a Fabry-Perot 374 and redirect the light onto the surface of an image sensor 376.

[0049] The Fabry-Perot 374 can be adjustable such that its cavity length range can be adjusted to the cavity length range of a sensing interferometer that can vary over time. Adjusting the total range of the Fabry-Perot to match the total range of the sensing interferometer can produce a maximum detection signal on the image sensor 376. For example, the Fabry-Perot 374 can have a spatially varying cavity length between 14000 nm and 19000 nm, and the sensing interferometer can have a cavity length of 15000 nm. In such a case, the position along the Fabry-Perot 374 where the cavity length of the Fabry-Perot is equal to 15000 nm can produce a maximum interferometer signal on the image sensor 376. The inventors have recognized and understood that the cavity length of the Fabry-Perot can at least partially depend on the angle at which the incident light ray travels through the interferometer. For example, as that angle increases, the cavity length can change such that, for a point on the Fabry-Perot 374, there can be some incident light energy perpendicular to the Fabry-Perot (e.g., 0° or 90°) and some incident light energy at one angle. Due to the incident light energy arriving at various angles, the resulting interferogram signal observed by the sensor 376 can correspond to the sum of all signals over that angle range, which can reduce the contrast of the detected signal.

[0050] Similar to the lens design shown in FIG. 4, the design of lens 372 shown in FIG. 8A can be implemented as a pair of D-shaped lenses having their curved edges facing each other. In the example of FIG. 8A, the pair of D-shaped lenses includes two symmetric lenses 810a, 810b (e.g., lenses having the same focal length) such that the maximum angle of incidence of the light rays received by lens 810a from connector 410 is the same as the maximum angle of the light rays exiting lens 810b. The maximum acceptance angle (i.e., the maximum angle of the light energy incident on sensor 376) is shown as α in the lens design of FIG. 8A. The inventors have recognized and understood that reducing the maximum acceptance angle α can increase the contrast of the signal redirected by Fresnel 374 onto sensor 376. In some embodiments described herein, the maximum acceptance angle α of the light energy output from lens 372 can be reduced by expanding the optical signal transmitted through lens 372.

[0051] The acceptance angle of the light rays output from the connector 410 and received by the lens 372 can generally be fixed without modification of the array and / or direction of the optical fibers within the connector 410. Some conventional solutions for reducing the acceptance angle include bending the optical fiber to block some modes of the optical signal. However, such techniques also reduce the overall energy in the signal, which may be undesirable in some applications where the amount of energy in the optical signal can be low. Some embodiments disclosed herein reduce the maximum acceptance angle α by using a lens 372 that expands the optical signal passing through the lens 372 (e.g., by selecting a lens or combination of lenses with appropriate focal length characteristics), rather than reducing the energy in the optical energy provided as an input to the lens 372. For a single-channel optical device in which a single line is generated on the sensor 376 (and thus crosstalk between lines on the sensor 376 need not be considered), the lens 372 can be configured using a single lens that provides an expansion of the optical signal received from the connector 410. In a multi-channel optical device in which multiple lines are generated on the sensor 376 (and thus crosstalk between lines on the sensor 376 can be important for distinguishing multiple interferogram signals), an example of which is described herein, the lens 372 can be configured using multiple lenses that collectively provide an expansion of the incident optical signal.

[0052] FIG. 8B schematically illustrates a detector module that includes a lens 372 configured to effect an expansion of an optical signal received from a connector 410 according to some embodiments. As shown in FIG. 8B, the lens 372 may be implemented as a set of asymmetric lenses 810b, 810c having different focal lengths. Collectively, the set of lenses 810b, 810c may provide an expansion of the optical signal received from the connector 410, which may then provide, at the output of the lens 810b, an optical signal having a reduced maximum acceptance angle β relative to the configuration shown in FIG. 8A where the symmetric lenses 810a, 810b are used (i.e., β < α). For example, if the focal length of the lens 810b is selected to be 7.8 and the focal length of the lens 810c is selected to be 5.5, the expansion factor of the lens 372 is 7.8 / 5.5 = 1.4. By reducing the maximum acceptance angle β, the contrast of the interferometer signal (e.g., peak-to-peak amplitude / average amplitude) is improved relative to when a larger maximum acceptance angle α is used.

[0053] Configuring the lens 372 to have a larger magnification reduces the maximum acceptance angle β, thereby improving the contrast of the signal. However, configuring the lens 372 to provide too large a magnification may have some undesirable results with respect to the signal captured by the sensor 376. FIG. 7A illustrates an example of an image of an interferogram signal captured by a two-dimensional image sensor (e.g., the image sensor 376 shown in FIG. 3) according to some embodiments in which the detector module includes a lens 372 configured using a set of symmetric lenses shown in FIG. 8A. FIG. 8A schematically illustrates an image 820 of a two-dimensional image sensor in which two lines corresponding to interferogram signals for a two-channel multi-channel optical pressure sensor are separated by a distance d1. FIG. 8B schematically illustrates an image 830 of a two-dimensional image sensor in which two lines corresponding to interferogram signals for two channels of a multi-channel optical pressure sensor enlarged using lenses 810b and 810c are separated by a distance d2. As can be observed by comparing image 820 and image 830, the magnification of the optical signal using the lens design of FIG. 8B results in more pixels being used to represent each of the interferogram signals on sensor 376 compared to using the lens design shown in FIG. 8A. By using additional pixels to represent the magnified interferogram signal, the processing resources required to process the captured signal (e.g., using the hardware processor 380 shown in FIG. 3) can be increased at higher magnifications compared to embodiments using smaller magnifications. Additionally, the distance between the two interferogram signals can also be increased (i.e., d2>d1), which can limit the number of additional channels of information that can be captured by sensor 376 without increasing its size. As should be understood, the selection of the optical components for the lens 372 to increase the magnification while reducing the spread of the detection signal on the sensor 376 and improving the contrast of the interferogram signal can be determined based on a particular application and / or Fizeau design.

[0054] The inventor has recognized that configuring the lens 372 to have a relatively small amount of magnification (e.g., 1.2x, 1.3x, 1.4x, 1.5x) can provide sufficient magnification to improve contrast while controlling the pixel spread of the interferogram signal on the sensor 376. For example, the pixel spread of the interferogram signal captured by the sensor 376 can be controlled within a reasonable range for several applications, including the multi-channel optical pressure sensor described herein, by selecting a suitable magnification factor for the lens 372. In some embodiments, the magnification factor of the lens 372 can be greater than 1.1, greater than 1.2, greater than 1.3, greater than 1.4, or greater than 1.5. In some embodiments, the magnification factor of the lens 372 can be less than 3, less than 2.5, less than 2, less than 1.5, less than 1.4, less than 1.3, or less than 1.2. In some embodiments, the magnification factor can be within any of the aforementioned ranges. For example, the magnification factor can be greater than 1.1 and less than 2, greater than 1.1 and less than 1.5, greater than 1.2 and less than 1.4, etc.

[0055] Some aspects and embodiments of the technology described in this disclosure have been thus described, so that it should be understood that various modifications, corrections, and improvements will readily occur to those skilled in the art. Such modifications, corrections, and improvements are intended to be within the spirit and scope of the technology described herein. For example, those skilled in the art can easily imagine various other means and / or structures for implementing the functions described herein and / or for obtaining one or more of the results and / or advantages described herein, and each such variation and / or correction is considered to be within the scope of the embodiments described herein. Those skilled in the art will be able to recognize or confirm many equivalents of the specific embodiments described herein using nothing more than routine experimentation. Accordingly, the foregoing embodiments are presented by way of example only, and it should be understood that within the scope of the appended claims and their equivalents, embodiments of the invention may be practiced otherwise than as specifically described. Additionally, any combination of two or more of the features, systems, articles, materials, kits, and / or methods described herein is included within the scope of the present disclosure if such features, systems, articles, materials, kits, and / or methods do not mutually conflict.

[0056] The above-described embodiments can be implemented in any of a number of ways. One or more aspects and embodiments of the present disclosure involving the implementation of a process or method can utilize program instructions executable by a device (e.g., a computer, a processor, or other device) to implement or control the implementation of the process or method. In this regard, various concepts of the present invention are embodied as a computer-readable storage medium (or multiple computer-readable storage media) (e.g., computer memory, one or more floppy (registered trademark) disks, compact disks, optical disks, magnetic tapes, flash memory, circuit configurations within a field programmable gate array or other semiconductor device, or other tangible computer storage media) encoded with one or more programs that, when executed on one or more computers or other processors, implement a method of implementing one or more of the above-described embodiments. The computer-readable medium or media can be transportable such that the program or programs stored thereon can be loaded onto one or more different computers or other processors to implement various ones of the above aspects. In some embodiments, the computer-readable medium can be a non-transitory medium.

[0057] The above-described embodiments of the present technology can be implemented in any of a number of ways. For example, an embodiment can be implemented using hardware, software, or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or set of processors, whether provided on a single computer or distributed among multiple computers. It should be understood that any component or set of components that perform the above functions can generally be regarded as a controller that controls the above functions. The controller can be implemented in a number of ways, such as using dedicated hardware or using general-purpose hardware (e.g., one or more processors) programmed with microcode or software to perform the functions listed above. When the controller corresponds to multiple components of the system, it can be implemented in a combination of ways.

[0058] Furthermore, it should be understood that the computer can be embodied in any of several forms, such as, by way of non-limiting example, a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, the computer can be incorporated within a device that is not generally regarded as a computer but has suitable processing capabilities, including, for example, a personal digital assistant (PDA), a smartphone, or any other suitable portable or fixed electronic device.

[0059] In addition, a computer may have one or more input and output devices. These devices can be used, among other things, to present a user interface. Examples of output devices that can be used to provide a user interface include a printer or display screen for visual presentation of output, and a speaker or other audio generating device for audible presentation of output. Examples of input devices that can be used for a user interface include a keyboard and pointing devices such as a mouse, touch pad, and digitizing tablet. As another example, a computer can receive input information through speech recognition or in other audible formats.

[0060] Such computers can be interconnected by one or more networks in any suitable form, including a local area network or wide area network (such as a corporate network, etc.) and an intelligent network (IN) or the Internet. Such networks can be based on any suitable technology, can operate according to any suitable protocol, and can include wireless networks, wired networks, or fiber optic networks.

[0061] Also, as described, some aspects can be embodied in one or more ways. The acts performed as part of a method can be ordered in any suitable way. Accordingly, embodiments can be constructed in which the acts are performed in an order different from that illustrated, which can include performing some acts simultaneously, even if they are shown as sequential acts in the illustrative embodiments.

[0062] All definitions as defined and used herein are to be understood as being preferred over dictionary definitions, definitions in incorporated documents by reference, and / or the ordinary meaning of the defined terms.

[0063] In the specification and claims, the indefinite articles "a" and "an" as used herein should be understood to mean "at least one" unless the contrary is clearly indicated.

[0064] In the specification and claims, the phrase "and / or" as used herein should be understood to mean "one or both" of the elements so combined, i.e., elements that exist conjunctively in some cases and disjunctively in other cases. The plurality of elements listed using "and / or" should be construed in the same manner, i.e., as "one or more" of the elements so combined. Other elements may optionally exist, whether or not they are related to those specifically identified elements, in addition to the elements specifically identified by the "and / or" clause. Thus, by way of non-limiting example, reference to "A and / or B", when used in combination with open-ended language such as "comprising", may refer in one embodiment to only A (optionally including elements other than B), in another embodiment to only B (optionally including elements other than A), or in yet another embodiment to both A and B (optionally including other elements).

[0065] As used in the specification and claims herein, the phrase "at least one" with respect to a list of one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but does not necessarily include at least one of every element specifically recited in the list of elements, nor does it exclude any combination of elements in the list of elements. This definition also allows for the possibility that there may optionally be elements other than those specifically identified in the list of elements that the phrase "at least one" refers to, whether or not they are related to those specifically identified elements. Thus, by way of non-limiting example, "at least one of A and B" (or equivalently "at least one of A or B", or equivalently "at least one of A and / or B") can, in one embodiment, refer to at least one A (optionally including elements other than B) that optionally includes more than one, and in the absence of any B; in another embodiment, refer to at least one B (optionally including elements other than A) that optionally includes more than one, and in the absence of any A; and in yet another embodiment, refer to at least one A that optionally includes more than one, and at least one B that optionally includes more than one (and optionally includes other elements).

[0066] Also, the terminology and expressions used herein are for the purpose of description and should not be regarded as limiting. The use of "including", "comprising", "having", "containing", "accompanied by" and their variations herein is intended to encompass the items listed hereinafter and their equivalents and additional items.

[0067] In the claims and the above specification, all transitional phrases such as "comprising", "including", "carrying", "having", "containing", "accompanying", "holding", "consisting of", etc. are open-ended, that is, they are understood to mean "including but not limited to". Only the transitional phrases "consisting of" and "consisting essentially of" are to be closed or semi-closed transitional phrases, respectively.

[0068] The use of ordinal terms such as "first", "second", "third", etc. in the claims to modify claim elements does not in itself imply any priority, precedence, or order of one claim element over another, or the chronological order in which acts of a method are performed, but is merely used as a label to distinguish one claim element having a certain name from another element having the same name (in the absence of the use of ordinal terms) for the purpose of distinguishing claim elements.

Claims

1. A multi-channel optical pressure sensor, wherein the multi-channel optical pressure sensor comprises: at least one light emitting diode (LED); a plurality of sensors, comprising a first sensor coupled to the at least one LED via at least one first optical fiber and a second sensor coupled to the at least one LED via at least one second optical fiber; a detector module coupled to the first sensor and the second sensor, the detector module comprising: at least one lens; an image sensor configured to detect light received from the at least one lens; and a detector module; at least one hardware processor configured to determine a first pressure measured by the first sensor and a second pressure measured by the second sensor based at least in part on light detected by the image sensor; A multi-channel optical pressure sensor.

2. The at least one LED comprises: a first LED configured to generate first light having a first spectrum; a second LED configured to generate second light having a second spectrum; The sensor according to claim 1.

3. The first spectrum has a peak wavelength in the range of 550 - 670 nm, and the second spectrum has a peak wavelength in the range of 800 - 900 nm. The sensor according to claim 2.

4. The first spectrum has a peak wavelength in the range of 550 - 600 nm. The sensor according to claim 3.

5. The first spectrum has a peak wavelength that is 4 / 5 of the peak wavelength of the second spectrum. The sensor according to claim 2.

6. The first LED and / or the second LED is smaller than 1 mm. The sensor according to claim 2.

7. The first LED and / or the second LED is a phosphor-converted LED. The sensor according to claim 2.

8. The at least one LED comprises a single LED having a wide spectrum. The sensor according to claim 1.

9. A first optical element arranged between the at least one LED and the plurality of sensors, the first optical element comprising: Receiving the first light and the second light; Outputting third light and fourth light, each of the third light and the fourth light having a third spectrum; A first optical element configured to perform the above; The sensor according to claim 2, further comprising the above.

10. The first optical element, the first sensor, and a second optical element coupled to the detector module; The first optical element, the second sensor, and a third optical element coupled to the detector module; The sensor according to claim 9, further comprising the above.

11. The second optical element is configured to provide first reflected light from the first sensor to the detector module; The sensor according to claim 10, wherein the third optical element is configured to provide second reflected light from the second sensor to the detector module.

12. The sensor according to claim 1, wherein the at least one lens is a plano lens.

13. The sensor according to claim 12, wherein the plano lens includes a set of D-shaped lenses having curved edges facing each other.

14. The sensor according to claim 12, wherein the at least one lens is configured to reduce spherical aberration in the light received from the first sensor and the second sensor.

15. The sensor according to claim 1, wherein the at least one lens is configured to expand light signal incidence on the at least one lens.

16. The sensor according to claim 15, wherein an expansion coefficient of the at least one lens is at least 1.1 and less than 3.

17. The sensor according to claim 16, wherein the expansion coefficient is less than 1.

5.

18. The sensor according to claim 17, wherein the expansion coefficient is less than 1.

3.

19. The sensor according to claim 15, wherein the at least one lens includes at least two lenses that collectively expand the light signal incidence on the at least one lens.

20. The sensor according to claim 19, wherein the at least two lenses include a first lens having a first focal length and a second lens having a second focal length different from the first focal length.

21. Each of the first lens and the second lens is a D-shaped lens having a curved edge. The sensor according to claim 20, wherein the curved edges of the first lens and the second lens are arranged to face each other.

22. The sensor according to claim 1, wherein the detector module further includes a Fresnel arranged between the at least one lens and the image sensor.

23. The sensor according to claim 22, wherein the image sensor includes a two-dimensional image sensor.

24. The sensor according to claim 23, wherein the at least one lens and the Fresnel are configured to collectively project the light received from the first sensor and the second sensor as two lines on the two-dimensional image sensor.

25. The sensor according to claim 24, wherein the two lines are two parallel lines.

26. Each of the two lines on the two-dimensional image sensor includes an interferogram, and determining the first pressure measured by the first sensor and the second pressure measured by the second sensor based at least in part on the light detected by the image sensor includes determining the first pressure and the second pressure based on the corresponding interferogram. The sensor according to claim 24.

27. A circulatory support device, the circulatory support device comprising a rotor, a motor configured to drive the rotation of the rotor at one or more speeds, a first optical pressure sensor configured to detect a first pressure signal, a second optical pressure sensor configured to detect a second pressure signal, at least one hardware processor, the at least one hardware processor configured to determine a differential pressure signal based at least in part on the first pressure signal and the second pressure signal at least one hardware processor and A circulatory support device comprising.

28. The circulatory support device according to claim 27, wherein the at least one hardware processor is further configured to determine a flow rate through the circulatory support device based at least in part on the differential pressure signal.

29. A first light emitting diode (LED) coupled to the first optical pressure sensor and the second optical pressure sensor, the first LED being configured to generate first light having a first spectrum, the first LED; A second LED coupled to the first optical pressure sensor and the second optical pressure sensor, the second LED being configured to generate second light having a second spectrum, the second LED The circulatory assist device according to claim 27, further comprising.

30. The circulatory assist device according to claim 29, wherein the first spectrum has a peak wavelength in the range of 550 to 670 nm, and the second spectrum has a peak wavelength in the range of 800 to 900 nm.

31. The circulatory assist device according to claim 30, wherein the first spectrum has a peak wavelength in the range of 550 to 600 nm.

32. The circulatory assist device according to claim 29, wherein the first spectrum has a peak wavelength that is 4 / 5 of the peak wavelength of the second spectrum.

33. The circulatory assist device according to claim 29, wherein the first LED and / or the second LED is smaller than 1 mm.

34. The circulatory assist device according to claim 29, wherein the first LED and / or the second LED is a phosphor-converted LED.

35. A first optical element, the first optical element Receiving the first light and the second light; Outputting third light and fourth light, each of the third light having a third spectrum, the third light being provided to the first optical pressure sensor, and the fourth light being provided to the second optical pressure sensor; The first optical element arranged to perform The circulatory assist device according to claim 29, further comprising.

36. A second optical element coupled to the first optical element and the first optical pressure sensor; A third optical element coupled to the first optical element and the second optical pressure sensor The circulatory assist device according to claim 35, further comprising.

37. Further comprising a detector module, The second optical element is configured to provide first reflected light from the first optical pressure sensor to the detector module. The circulatory assist device according to claim 36, wherein the third optical element is configured to provide second reflected light from the second optical pressure sensor to the detector module.

38. A detector module coupled to the first optical pressure sensor and the second optical pressure sensor, the detector module comprising: at least one lens; an image sensor configured to detect light received from the at least one lens and a detector module The circulatory assist device according to claim 29, further comprising.

39. The circulatory assist device according to claim 38, wherein the at least one lens includes a plano lens.

40. The circulatory assist device according to claim 39, wherein the plano lens includes a pair of D-shaped lenses having curved edges facing each other.

41. The circulatory assist device according to claim 38, wherein the at least one lens is configured to reduce spherical aberration in the light received from the first optical pressure sensor and the second optical pressure sensor.

42. The circulatory assist device according to claim 27, wherein the at least one lens is configured to expand light signal incidence on the at least one lens.

43. The circulatory assist device according to claim 42, wherein the magnification factor of the at least one lens is at least 1.1 and less than 3.

44. The circulatory assist device according to claim 43, wherein the magnification factor is less than 1.

5.

45. The circulatory assist device according to claim 44, wherein the magnification factor is less than 1.

3.

46. The circulatory assist device according to claim 42, wherein the at least one lens includes at least two lenses that collectively expand the light signal incidence on the at least one lens.

47. The circulatory assist device according to claim 46, wherein the at least two lenses include a first lens having a first focal length and a second lens having a second focal length different from the first focal length.

48. Each of the first lens and the second lens is a D-shaped lens having a curved edge, and the curved edges of the first lens and the second lens are arranged to face each other. The circulatory assist device according to claim 47.

49. The detector module further includes a Fresnel arranged between the at least one lens and the image sensor, the circulatory assistance device according to claim 27.

50. The detector module further includes a Fresnel arranged between the at least one lens and the image sensor, the circulatory assistance device according to claim 38.

51. The image sensor includes a two-dimensional image sensor, the circulatory assistance device according to claim 50.

52. The at least one lens and the Fresnel are configured to collectively project the light received from the first optical pressure sensor and the second optical pressure sensor as two lines on the two-dimensional image sensor, the circulatory assistance device according to claim 51.

53. The two lines are two parallel lines, the circulatory assistance device according to claim 52.

54. Each of the two lines on the two-dimensional image sensor includes an interferogram, The at least one hardware processor is further configured to determine the first pressure and the second pressure based on the corresponding interferogram, and thus, based at least in part on the light detected by the image sensor, determine the first pressure measured by the first optical pressure sensor and the second pressure measured by the second optical pressure sensor, Determining the differential pressure signal based at least in part on the first pressure signal and the second pressure signal includes determining the differential pressure signal based on the first pressure and the second pressure, the circulatory assistance device according to claim 52.

Images