Dialysis system with reduced valve noise

Abstract

Systems and methods for reducing noise in solenoid valve activation and deactivation in a peritoneal dialysis ("PD") system are disclosed. In at least one embodiment, the PD system operates with the solenoid valve under the control of the control unit. The control unit takes measures to control the movement of the solenoid valve to minimize the amount of sound occurring at the time of an impact during activation and deactivation of the valve. These measures include slowing down movement of the valve plunger within the valve coil. In one aspect, the valve plunger may be slowed down by applying a voltage to the valve coil via pulse width modulation ("PWM").

Description

Technical Field

[0001] The present disclosure generally relates to medical fluid treatment and, more particularly, to dialysis fluid treatment that uses valves for medical fluid control. Background Art

[0002] For various reasons, a person's renal system may fail. Renal failure produces several physiological disorders. It is no longer possible to balance water and minerals or excrete the daily metabolic load. Toxic metabolic end products, such as urea, creatinine, uric acid, etc., may accumulate in the patient's blood and tissues.

[0003] Dialysis treats reduced kidney function and, in particular, kidney failure. Dialysis removes waste products, toxins, and excess water that a normally functioning kidney would otherwise remove from the body. Dialysis treatment for replacing kidney function is critical for many people because the treatment is life-saving.

[0004] One type of kidney failure therapy is hemodialysis ("HD"), which typically uses diffusion to remove waste products from a patient's blood. A diffusion gradient occurs across a semipermeable dialyzer between the blood and an electrolyte solution called dialysate or dialysis fluid to cause diffusion.

[0005] Hemofiltration ("HF") is an alternative renal replacement therapy that relies on convective transport of toxins from a patient's blood. HF is achieved by adding replacement or substitution fluid to the extracorporeal circuit during treatment. The substitution fluid and the fluid that accumulates in the patient between treatments are ultrafiltered during the course of an HF treatment, providing a convective transport mechanism that is particularly beneficial for removing medium and large molecules.

[0006] Hemodiafiltration ("HDF") is a treatment modality that combines convective clearance and diffusive clearance. HDF uses dialysis fluid that flows through a dialyzer, similar to standard hemodialysis, to provide diffusive clearance. In addition, a substitution solution is provided directly to the extracorporeal circuit to provide convective clearance.

[0007] Most HD, HF, and HDF treatments are performed at a center. There is currently a trend towards home hemodialysis (“HHD”), in part because HHD can be performed daily, providing therapeutic benefits superior to those of center hemodialysis treatments, which are typically performed every two or three weeks. Studies have shown that more frequent treatments remove more toxins and wastes and result in less interdialytic fluid overload compared to patients receiving less frequent but potentially longer treatments. Patients receiving more frequent treatments do not experience as many down cycles (fluctuations in fluid and toxins) as center patients, who have accumulated toxins over two or three days prior to treatment. In some areas, the nearest dialysis center may be many miles from a patient's home, resulting in a door-to-door treatment time consuming most of a day. Treatments at a center near the patient's home may also consume most of a patient's day. HHD can be performed at night or during the day while the patient relaxes, works, or otherwise produces.

[0008] Another type of kidney failure therapy is peritoneal dialysis (“PD”), which injects a dialysis solution (also called dialysis fluid) into the peritoneal cavity of a patient via a catheter. The dialysis fluid contacts the peritoneum in the patient's peritoneal cavity. Wastes, toxins, and excess water pass from the patient's bloodstream through the capillaries in the peritoneum and enter the dialysis fluid due to diffusion and osmosis, i.e., an osmotic gradient occurs across the membrane. Osmotic agents in the PD dialysis fluid provide the osmotic gradient. The used or spent dialysis fluid is drained from the patient's body, removing wastes, toxins, and excess water from the patient's body. This cycle is repeated, for example, several times.

[0009] There are various types of peritoneal dialysis therapies, including continuous ambulatory peritoneal dialysis (“CAPD”), automated peritoneal dialysis (“APD”), tidal flow dialysis, and continuous flow peritoneal dialysis (“CFPD”). CAPD is a manual dialysis treatment. Here, the patient manually connects the implanted catheter to the drain outlet to allow the used or spent dialysis fluid to drain from the peritoneal cavity. The patient then switches the fluid connection so that the patient catheter is connected to a bag of fresh dialysis fluid to infuse the fresh dialysis fluid into the patient's body through the catheter. The patient disconnects the catheter from the fresh dialysis fluid bag and allows the dialysis fluid to remain in the peritoneal cavity, where the transfer of wastes, toxins, and excess water occurs. After the dwell period, the patient repeats the manual dialysis procedure, for example, four times a day. Manual peritoneal dialysis requires a significant amount of time and effort from the patient, leaving room for improvement.

[0010] Automated peritoneal dialysis (“APD”) is similar to CAPD in that the dialysis treatment involves drain, fill, and dwell cycles. However, the APD machine typically performs the cycles automatically while the patient is sleeping. The APD machine frees the patient from having to perform the treatment cycles manually and from having to transport supplies during the day. The APD machine is fluidly connected to an implanted catheter, a source or bag of fresh dialysis fluid, and a fluid drain outlet. The APD machine pumps fresh dialysis fluid from the dialysis fluid source through the catheter and into the patient's peritoneal cavity. The APD machine also allows the dialysis fluid to dwell in the cavity and allows the transfer of waste, toxins, and excess water to occur. The source can include multiple liters of dialysis fluid, which includes several solution bags.

[0011] The APD machine pumps used or spent dialysis fluid out from the patient's peritoneal cavity through the catheter. As with the manual process, several drain, fill, and dwell cycles occur during dialysis. A “last fill” can occur at the end of the APD treatment. The last fill fluid can be retained in the patient's peritoneal cavity until the next treatment begins, or can be manually drained at some point during the day.

[0012] Except for CAPD, which typically does not involve machinery, each of the above dialysis modalities uses automated valves to control whether dialysis fluid, blood, or other fluids can flow. The valves also control the direction of fluid flow, such as where the fluid comes from or the destination to which the fluid flows. Different types of valves are used in dialysis systems. One type of valve is typically used with a disposable cartridge that has a rigid plastic component that defines a fluid flow path and a valve seat, and one or more flexible membranes that cover one or more sides of the rigid plastic component. The disposable cartridge is typically loaded into a dialysis machine or cycler that is capable of closing a designated portion of one or more plastic sheets against the valve seat to block fluid flow and forcing or allowing the plastic to move away from the valve seat to allow fluid flow.

[0013] Another type of automatic valve is a pinch valve, which alternatively clamps shut a tube carrying dialysis fluid, blood, or other fluids to block fluid flow. Here, no hard plastic disposable cartridge is required, thus saving costs. There are generally two types of pinch valves, electromagnetic pinch valves and electric pinch valves. Another type of automatic valve is an electromagnetic plunger valve. The electromagnetic plunger valve uses a plunger to move a lever that is pressed against a seat to stop flow (or move the lever to press against the seat to cause flow). One problem with electromagnetic pinch valves and electromagnetic plunger valves (collectively referred to herein as "solenoid valves") is noise. For example, an electromagnetic plunger valve typically involves energizing a coil that moves a plunger within a housing. The plunger can move when the coil is energized to allow the tube to open for fluid flow. When energy is removed from the coil, a compression spring is allowed to push the plunger in the opposite direction against a stop or wall located at the opposite end of the tube to block the tube. The plunger moving in either direction encounters a travel end point that involves the plunger directly or in contact with a fixed surface using the tube therebetween. The end-of-travel contact generates noise. Especially for APD treatment (which typically occurs at night while the patient is sleeping), the noise from the solenoid valve may disturb the patient and is problematic.

[0014] Another problem with solenoid valves is how to know that the valve has opened upon energization. That is, knowing that the energization of the coil has actually moved the plunger (e.g., in an electromagnetic plunger valve) or actually removed the clamping of the tube (e.g., in an electromagnetic pinch valve) such that it no longer blocks the tube or fluid flow. Assuming the valve is open when it is not may result in undesirable situations.

[0015] For each of the above problems, an improved method of operating a solenoid valve is needed. SUMMARY OF THE INVENTION

[0016] The present disclosure describes methods for operating solenoid valves used in medical fluid systems (such as automated peritoneal dialysis ("PD") systems), which improve the usability of the valves. Although the system is mainly described in connection with PD, the improved solenoid valve operation of the present disclosure is applicable to machines for any dialysis modality described herein, such as online HD, HF, HDF, and acute HD, HF, HDF. The improved solenoid valve operation of the present disclosure is also applicable to any medical fluid system in which the flow of treatment fluid or patient fluid is controlled via one or more valves.

[0017] In the PD example, the system includes a PD machine or cycler. The PD machine is mainly described herein as a durable system that attempts to limit disposable waste as much as possible, for example, via the use of an electromechanical piston pump that pumps a medical fluid or PD fluid through the body of the pump. The PD fluid pump can also be an electromechanically driven gear, peristaltic pump, or centrifugal pump. In another alternative embodiment, a pneumatically driven PD fluid pump can be employed. Any of the above pumping schemes can be used in combination with the electromechanically actuated solenoid valves of the present disclosure. In one embodiment, the PD machine or cycler is capable of delivering fresh, heated PD fluid to a patient at a pressure of, for example, 14 kPa (2.0 psig) or higher. The PD machine is capable of removing used PD fluid or effluent from the patient at a negative pressure of, for example, -9 kPa (-1.3 psig) or even greater. The fresh PD fluid delivered to the patient can first be heated to body fluid temperature, for example, 37 °C.

[0018] The PD machine or cycler also includes a plurality of valves, any one or more or all of which can be solenoid valves. The solenoid valves discussed herein can be of any kind or type. For example, one type of solenoid valve uses an internal fluid path that opens or closes depending on whether the coil is energized. This type of solenoid valve is well suited for durable or reusable versions of the PD machine or cycler. Another type of solenoid valve operates by not closing or closing a flexible tube depending on whether the coil is energized. This type of solenoid valve is well suited for versions of the PD machine or cycler that operate with a disposable kit, but can also be used with durable versions of the PD machine or cycler that will have internal flexible tubing for operating with the solenoid valve.

[0019] Noise reduction

[0020] The PD machine or cycler of the present system operates with the solenoid valve under the control of a control unit. In various embodiments, the control unit takes measures to control the movement of the solenoid valve to minimize the amount of sound that occurs during shock during valve enabling and disabling. These measures generally include slowing down the movement of the valve plunger within the valve coil. Any modification that slows down the movement of the valve will result in less shock with the valve housing and produce a lower level of shock sound.

[0021] One structure and method for slowing down solenoid valve actuation is to provide electronics for controlling the valve with a transistor ramp. The transistor can be used to linearly control the voltage applied to the coil of the solenoid valve. There are different variants of transistors that can be used to slow down solenoid valve actuation, including NPN-transistors and metal oxide semiconductor field effect transistors ("MOSFETs"). The two different types of transistors have different capabilities and advantages.

[0022] The system of the present disclosure provides a control unit for controlling the solenoid valve of the present disclosure, which has one or more processors and one or more memories. For example, the control unit can provide electrical control for using ON / OFF signals to control an NPN-transistor. In one embodiment, the control unit maintains the control signal at a low level, for example, in the non-saturation region of the transistor, where the voltage applied to the electromagnetic coil increases over time by increasing the input current to the transistor. The electrical result here is similar to that of a low-pass filter, without the need for large capacitors or resistors placed in series with the electromagnet. One disadvantage of using an NPN-transistor to slow down the power applied to the solenoid valve coil is that the NPN-transistor has a relatively high resistance that generates heat.

[0023] The control unit of the present disclosure can alternatively operate with one or more MOSFETs (such as P-channel MOSFETs). Here, the control unit provides a digital output control signal to the MOSFET. When the control signal from the control unit to the first MOSFET goes high via a ramp device, the output signal from the second MOSFET increases over time until it reaches the voltage Vin of the electromagnetic coil. When the control signal from the control unit to the first MOSFET goes low (e.g., the control signal is ramped via the associated device between the control unit and the first MOSFET), the output voltage from the second MOSFET slowly ramps down to 0V. The time for the voltage to ramp up and ramp down can be adjusted by changing the value of the associated capacitor. The ramp change of the electromagnetic voltage caused by using the MOSFET increases the undesirable turn-on and turn-off delays in the control of the solenoid valve. To shorten the delay, an initial ramp offset can be added to the circuit. In one embodiment, the offset value is set to a voltage close to the lowest voltage that causes the valve plunger to move. In one embodiment, the ramp offset voltage is set by adjusting the feedback resistor in the circuit. One benefit of using a MOSFET to slowly start and stop the valve from ramping is that there is less electromagnetic interference ("EMI") radiated and / or conducted due to the presence of reproducible and / or rapidly changing voltage flanks.

[0024] Another alternative structure and method for slowing solenoid valve actuation is to use Pulse Width Modulation (“PWM”). The advantage of PWM over simply reducing the supply voltage is that full voltage is ultimately applied to the electromagnetic coil, which substantially ensures the movement of the plunger of the solenoid valve. In one embodiment, the control unit applies PWM by pulsing the input voltage ON / OFF and increasing the voltage over time until the plunger of the solenoid valve moves to the valve open position (two-way valve) or the flow path switching position (three-way valve). This pulsing and ramped change allows for slower movement of the plunger and thus less shock to the valve housing during actuation and deactivation, thereby reducing noise. PWM is also available during normal operation (e.g., steady-state operation that requires a smaller voltage), which allows for a reduction in the total power demand during treatment, thus keeping the PD machine or cycler cooler. For example, during steady-state operation, a smaller voltage (e.g., 12 to 16 VDC) may be required to hold the plunger in the open position compared to the voltage typically required for valve actuation or valve deactivation (e.g., approximately 24 VDC). Thus, the PWM applied during steady-state operation will result in lower power consumption.

[0025] In a PWM example, the main processor of the control unit provides a command to the input / output driver of the control unit to energize one of the solenoid valves in the PD machine. The input / output driver sets the ON / OFF cycle for the PWM signal to the coil of the solenoid valve, e.g., 0 to 100% every 50 milliseconds (“ms”). After the plunger of the solenoid valve has reached its end-of-travel position, the input / output driver reduces the voltage level to, for example, 50% of the final actuation power level (e.g., to keep the valve energized in the open position), thereby reducing power consumption and heat generation. When it is time to close the two-way valve or switch the flow path of the three-way valve, the I / O driver causes the PWM voltage level to drop from the 50% plunger-holding level to zero, for example, within 50 ms.

[0026] The duration of the ramp-up or ramp-down of the voltage applied to the electromagnetic coil of the valve can be adjusted for any of the methods described herein for noise reduction. For example, resistors and / or capacitors can be arranged between the control unit and one of the NPN transistors, MOSFETs, or I / O nodes associated with the valve. The resistance value and / or capacitance value can be selected to set the duration of the ramp-up and / or ramp-down accordingly.

[0027] Evaluating functions enabled by solenoid valves

[0028] As discussed herein, solenoid valves are typically opened by energizing a coil that moves a plunger within the solenoid valve (e.g., as in an electromagnetic plunger valve) and / or releases a clamping state of a tube (e.g., as in an electromagnetic pinch valve). However, it is desirable and necessary to evaluate whether a solenoid valve of a medical fluid machine or a circulator (e.g., PD, HD, HF, HDF, and / or CRRT machines or circulators) has actually opened when energized, or has actually closed when de-energized or disabled. If not, the following may occur: the dialysis fluid does not flow when it should, or the dialysis fluid flows when it should not. Various embodiments of the systems and methods of the present disclosure are provided for evaluating valve enabling (e.g., whether the valve has opened correctly) or valve disabling (e.g., whether the valve has actually closed). In at least one embodiment, measurements of current values can be received from the solenoid valve at a predetermined sampling rate for a predetermined duration to generate a current curve of the solenoid valve. A polynomial model, such as a fifth-degree polynomial model, can be fit to the current curve and optimized. The optimized polynomial model can be applied to a trained classification model (e.g., a trained support vector machine (“SVM”)) to determine whether the current curve indicates that the corresponding solenoid valve has actually opened or closed.

[0029] A trained classification model, such as a trained SVM, can include a supervised learning model that analyzes training data (e.g., a plurality of current curves used as references (referred to herein as reference current curves), and knowledge of whether each reference current curve corresponds to a successful enabling or a failed enabling) in order to automatically learn (e.g., via an iterative error minimization process) the relationship between input data (e.g., various parameters of any given current curve) and two or more discrete outcomes (e.g., whether the current curve corresponds to a successful enabling or a failed enabling). The learned relationship can then be applied to test data with an unknown outcome (e.g., the current curve of a valve with an unknown valve enabling state) to determine the outcome (e.g., whether the valve has actually been successfully enabled). The SVM can be an example of a classification model, where the learned relationship is a decision boundary (e.g., separating the current curves of valves with successful valve enabling from the current curves of valves with failed valve enabling).

[0030] According to the disclosure set forth herein and without limiting the disclosure in any way, in a first aspect of the disclosure that can be combined with any other aspect or portion thereof, a medical fluid system includes: a control unit; a plurality of NPN transistors configured to control a plurality of valves in response to control signals received from the control unit; a plurality of valves, wherein each valve includes a housing, a coil, and a plunger, and wherein each valve is configured to allow medical fluid flow through a tube by applying a voltage to a corresponding coil via an associated NPN transistor to move a corresponding plunger within a corresponding housing; and wherein the control unit includes at least one processor and at least one memory, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the at least one processor to: send a control signal to one of the NPN transistors, the control signal being configured to cause a ramp-up of an input current to the NPN transistor, wherein the ramp-up of the input current to the NPN transistor causes a corresponding valve to ramp up the voltage applied to the corresponding coil, and wherein the ramp-up of the voltage applied to the corresponding coil causes the corresponding plunger to move in a manner that reduces the sound generated by the corresponding plunger as compared to operation without the NPN transistor.

[0031] In a second aspect of the disclosure that can be combined with any other aspect or portion thereof, the control signal is configured to place the NPN transistor in the non-saturation region.

[0032] In a third aspect of the disclosure that can be combined with any other aspect or portion thereof, each valve is configured to close the medical fluid flow through the tube by not applying the voltage caused by the corresponding NPN transistor to the corresponding coil such that the corresponding plunger moves in an opposite direction to occlude the corresponding tube.

[0033] In a fourth aspect of the disclosure that can be combined with any other aspect or portion thereof, the instructions, when executed by the at least one processor, further cause the at least one processor to: turn off a low control signal, wherein the turn-off causes a ramp-down of the input current to the NPN transistor, wherein the ramp-down of the input current to the NPN transistor causes a corresponding valve to ramp down the voltage applied to the corresponding coil, and wherein the ramp-down of the voltage applied to the corresponding coil causes the corresponding plunger to move in an opposite direction and in a manner that reduces the sound generated by the corresponding plunger as compared to operation without the NPN transistor.

[0034] In a fifth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, a medical fluid system includes: a control unit; a plurality of metal-oxide semiconductor field-effect transistors (“MOSFETs”) configured to control a plurality of valves in response to control signals received from the control unit; a plurality of valves, where each valve includes a housing, a coil, and a plunger, and where each valve is configured to allow medical fluid flow through a tube by applying a voltage to the corresponding coil via the associated MOSFET to move the corresponding plunger within the corresponding housing; the control unit includes at least one processor and at least one memory, where the at least one memory stores instructions that, when executed by the at least one processor, cause the at least one processor to: send a high digital control signal to one of the MOSFETs, where in response to the high digital control signal, the MOSFET ramps up the voltage applied to the corresponding coil until the voltage reaches a predetermined input voltage Vin, and where the ramping up of the voltage applied to the corresponding coil causes the corresponding plunger to move in a manner that reduces the sound generated by the corresponding plunger compared to operation without the MOSFET.

[0035] In a sixth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, each valve is configured to close the medical fluid flow through the tube by not applying a voltage to the corresponding coil via the corresponding MOSFET such that the corresponding plunger moves in the opposite direction to block the corresponding tube.

[0036] In a seventh aspect of the present disclosure, which can be combined with any other aspect or parts thereof, the instructions, when executed by the at least one processor, further cause the at least one processor to: send a low digital control signal to the MOSFETs among the plurality of MOSFETs, where in response to the low digital control signal, the MOSFET causes the corresponding valve to ramp down the voltage applied to the corresponding coil until the voltage reaches 0 volts, and where the ramping down of the voltage applied to the corresponding coil causes the corresponding plunger to move in the opposite direction and in a manner that reduces the sound generated by the corresponding plunger compared to operation without the MOSFET.

[0037] In an eighth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, the medical fluid system further includes at least one resistor arranged in series between the control unit and the MOSFETs; where the duration of the ramping up of the voltage applied to the corresponding coil is based on at least one resistance value of the corresponding at least one resistor; and where the duration of the ramping down of the voltage applied to the corresponding coil is based on at least one resistance value of the corresponding at least one resistor.

[0038] In a ninth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, the medical fluid system further includes at least one capacitor arranged in series between the control unit and the MOSFET; wherein the duration of the ramp-up of the voltage applied to the corresponding coil is further based on the capacitance value of the corresponding at least one capacitor; and wherein the duration of the ramp-down of the voltage applied to the corresponding coil is further based on the capacitance value of the corresponding at least one capacitor.

[0039] In a tenth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, the medical fluid system further includes an initial ramp offset circuit, and the initial ramp offset circuit includes a feedback resistor.

[0040] In an eleventh aspect of the present disclosure, which can be combined with any other aspect or parts thereof, the instructions, when executed, further cause the processor: to apply an offset voltage via the initial ramp offset circuit, and the offset voltage is set to be lower than the voltage applied to the corresponding coil when ramping up the input current to the MOSFET.

[0041] In a twelfth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, a medical fluid system includes: a control unit; a plurality of input / output ("I / O") nodes configured to control a plurality of valves via pulse width modulation ("PWM") signals in response to control signals received from the control unit; a plurality of valves, wherein each valve includes a housing, a coil, and a plunger, and wherein each valve is configured to allow the flow of medical fluid through a tube by applying a voltage to the corresponding coil via the associated I / O node to move the corresponding plunger within the corresponding housing; and the control unit includes at least one processor and at least one memory, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the at least one processor: to send a control signal to one of the plurality of I / O nodes, the control signal causing the one I / O node to apply a PWM signal to the corresponding coil and cause the PWM signal to ramp up, and wherein the ramp-up of the PWM signal causes the corresponding plunger to move in a manner that reduces the sound generated by the corresponding plunger compared to the operation without the PWM signal.

[0042] In a thirteenth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, the ramp-up of the PWM signal includes ramping up the duty cycle of the pulsed voltage applied to the corresponding coil from 0% to 100% during 50 ms.

[0043] In a fourteenth aspect of the present disclosure, which can be combined with any other aspect or part thereof, the instructions, when executed, further cause the processor to: after the plunger reaches the end position, send a second control signal to the I / O node, the second control signal causing the I / O node to ramp down the PWM signal to the corresponding coil to a duty cycle of at least 25%.

[0044] In a fifteenth aspect of the present disclosure, which can be combined with any other aspect or part thereof, the second control signal causes the I / O node to ramp down the PWM signal to the corresponding coil to a duty cycle of at least 50%.

[0045] In a sixteenth aspect of the present disclosure, which can be combined with any other aspect or part thereof, each valve is configured to close the flow of medical fluid through the tube by moving the corresponding plunger in the opposite direction to block the corresponding tube by not applying voltage to the corresponding coil via the corresponding I / O node.

[0046] In a seventeenth aspect of the present disclosure, which can be combined with any other aspect or part thereof, the instructions, when executed by at least one processor, further cause the at least one processor to: send a third control signal to the I / O node, the third control signal causing the I / O node to ramp down the PWM signal to the corresponding coil to a duty cycle of 0%, wherein the ramp down of the PWM signal to the corresponding coil causes the corresponding plunger to move in the opposite direction and in a manner that reduces the sound generated by the corresponding plunger compared to operation without a PWM signal.

[0047] In an eighteenth aspect of the present disclosure, which can be combined with any other aspect or part thereof, the ramping down of the PWM signal to the corresponding coil to a duty cycle of 0% occurs between 25 ms and 75 ms.

[0048] In a nineteenth aspect of the present disclosure, which can be combined with any other aspect or part thereof, the medical fluid system further includes at least one resistor arranged in series between the control unit and the I / O node; wherein the duration of the ramp up of the PWM signal is based on the resistance value of the corresponding at least one resistor; and wherein the duration of the ramp down of the PWM signal is based on the resistance value of the corresponding at least one resistor.

[0049] In a twentieth aspect of the present disclosure, which can be combined with any other aspect or part thereof, the medical fluid system further includes at least one capacitor arranged in series between the control unit and the I / O node; wherein the duration of the ramp up of the PWM signal is further based on the capacitance value of the corresponding at least one capacitor; and wherein the duration of the ramp down of the PWM signal is further based on the capacitance value of the corresponding at least one capacitor.

[0050] In a twenty - first aspect of the present disclosure that can be combined with any other aspect or parts thereof, a medical fluid system includes a plurality of valves, where each valve includes a housing, a coil, and a plunger. Each valve is configured to allow the flow of medical fluid through a tube by energizing a corresponding coil to move a corresponding plunger within a corresponding housing, and each valve is configured to close the flow of medical fluid through the tube by de - energizing the corresponding coil to move the corresponding plunger in the opposite direction within the corresponding housing to block the corresponding tube; at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the at least one processor to: receive current values measured at a predetermined sampling rate over a predetermined duration during the enabling of at least one valve among the plurality of valves, generate a current curve for the at least one valve based on the corresponding measured current values of the at least one valve, generate a polynomial model for the at least one valve based on the corresponding current curve of the at least one valve, and apply the corresponding polynomial model to a trained classification model for the at least one valve to evaluate the enabling state of the valve.

[0051] In a twenty - second aspect of the present disclosure that can be combined with any other aspect or parts thereof, the enabling state indicates one of a successful enabling or a failed enabling, and where the instructions, when executed, further cause the system to: generate an alert indicating a fault of the valve associated with the failed enabling based on the enabling state indicating a failed enabling.

[0052] In a twenty - third aspect of the present disclosure that can be combined with any other aspect or parts thereof, the instructions, when executed, cause the system to generate the polynomial model by: applying a fifth - degree polynomial model with initialized parameters to the current curve of the at least one valve; and optimizing the parameters of the fifth - degree polynomial model via least - mean - square estimation.

[0053] In a twenty - fourth aspect of the present disclosure that can be combined with any other aspect or parts thereof, the instructions, when executed, cause the system to generate a current curve for at least one valve by: normalizing the measured current values of at least one valve using the maximum current value.

[0054] In a twenty - fifth aspect of the present disclosure that can be combined with any other aspect or parts thereof, the instructions, when executed, cause the system to normalize the measured current values by: identifying the current rise time of the at least one valve based on the measured current values of the at least one valve; and determining the maximum current for normalizing the measured current values of the at least one valve based on the current rise time of the at least one valve.

[0055] In a twenty-sixth aspect of the present disclosure, which may be combined with any other aspect or portions thereof, the trained classification model is one or more of the following: a support vector machine trained using a reference data set including a plurality of reference current curves having known enabled states; or a logistic regression model trained using a reference data set including a plurality of reference current curves having known enabled states.

[0056] In a twenty-seventh aspect of the present disclosure, which may be combined with any other aspect or portions thereof, the instructions, when executed, further cause the system to: receive a first reference data set including a plurality of reference current curves indicating successful enabling before applying the corresponding polynomial model to the trained classification model; receive a second reference data set including a plurality of reference current curves indicating failed enabling; label the first reference data set and the second reference data set with positive and negative outputs, respectively; iteratively test one or more decision boundaries separating the first reference data set and the second reference data set; and generate a trained classification model after convergence of an optimized decision boundary.

[0057] In a twenty-eighth aspect of the present disclosure, which may be combined with any other aspect or portions thereof, a medical fluid system includes a plurality of valves, where each valve includes a housing, a coil, and a plunger, where each valve is configured to allow medical fluid flow through a tube by energizing a corresponding coil to move a corresponding plunger within a corresponding housing, and where each valve is configured to close the medical fluid flow through the tube by de-energizing the corresponding coil to move the corresponding plunger in an opposite direction within the corresponding housing to occlude the corresponding tube; at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the at least one processor to: receive current values measured at a predetermined sampling rate for a predetermined duration during deactivation of at least one of the plurality of valves, generate a current curve for the at least one valve based on the corresponding measured current values of the at least one valve, generate a polynomial model for the at least one valve based on the corresponding current curve of the at least one valve, and apply the corresponding polynomial model to a trained classification model for the at least one valve to evaluate the deactivation state of the at least one valve.

[0058] In a twenty-ninth aspect of the present disclosure, which may be combined with any other aspect or portions thereof, the deactivation state indicates one of successful deactivation or failed deactivation, where the instructions, when executed, further cause the system to: generate an alert indicating a fault of a valve associated with the failed deactivation based on the deactivation state indicating failed deactivation.

[0059] In a thirtieth aspect of the present disclosure, which can be combined with any other aspect or part thereof, there is provided a method for evaluating a function enabled by a solenoid valve, the method comprising: receiving, by a control unit of a medical fluid system having at least one processor and during the enabling of at least one valve among a plurality of valves controlled by the control unit, current values measured at a predetermined sampling rate over a predetermined duration, wherein each valve comprises a housing, a coil, and a plunger, wherein each valve is configured to enable a flow of medical fluid through a tube by energizing a corresponding coil to move a corresponding plunger within a corresponding housing, and wherein each valve is configured to close the flow of medical fluid through the tube by de-energizing the corresponding coil to move the corresponding plunger in an opposite direction within the corresponding housing to block the corresponding tube; generating, based on the respective measured current values of the at least one valve, a current curve of the at least one valve; generating, based on the respective current curves of the at least one valve, a polynomial model of the at least one valve; and applying, for the at least one valve, the respective polynomial model to a trained classification model to evaluate the enabling state of the valve.

[0060] In a thirty-first aspect of the present disclosure, which can be combined with any other aspect or part thereof, the enabling state indicates one of a successful enabling or a failed enabling, and the method further comprises: generating, based on the enabling state indicating a failed enabling, an alert indicating a fault of the valve associated with the failed enabling.

[0061] In a thirty-second aspect of the present disclosure, which can be combined with any other aspect or part thereof, generating the polynomial model comprises: applying a fifth-degree polynomial model with initialized parameters to the current curves of at least one valve; and optimizing the parameters of the fifth-degree polynomial model via least mean square estimation.

[0062] In a thirty-third aspect of the present disclosure, which can be combined with any other aspect or part thereof, generating the current curve of at least one valve comprises: normalizing the measured current values of at least one valve using a maximum current value.

[0063] In a thirty-fourth aspect of the present disclosure, which can be combined with any other aspect or part thereof, normalizing the measured current values of at least one valve comprises: identifying, based on the measured current values of at least one valve, a current rise time of at least one valve; and determining, based on the current rise time of at least one valve, a maximum current for normalizing the measured current values of at least one valve.

[0064] In a thirty-fifth aspect of the present disclosure, which can be combined with any other aspect or part thereof, the trained classification model is one or more of the following: a support vector machine trained using a reference data set comprising a plurality of reference current curves having known enabling states; or a logistic regression model trained using a reference data set comprising a plurality of reference current curves having known enabling states.

[0065] In a thirty-sixth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, the method further includes, before applying the corresponding polynomial model to the trained classification model: receiving a first reference data set including a plurality of reference current curves indicating successful enabling; receiving a second reference data set including a plurality of reference current curves indicating failed enabling; respectively labeling the first reference data set and the second reference data set with positive and negative outputs; iteratively testing one or more decision boundaries separating the first reference data set and the second reference data set; and generating a trained classification model after convergence based on the optimized decision boundary.

[0066] In a thirty-seventh aspect of the present disclosure, which can be combined with any other aspect or parts thereof, a method for evaluating the functionality of solenoid valve deactivation includes, during deactivation of at least one valve of a medical fluid system having at least one processor and controlled by the control unit, receiving current values measured at a predetermined sampling rate over a predetermined duration, wherein each valve includes a housing, a coil, and a plunger, wherein each valve is configured to enable the flow of medical fluid through a tube by energizing a corresponding coil to move a corresponding plunger within a corresponding housing, and wherein each valve is configured to close the flow of medical fluid through the tube by de-energizing the corresponding coil to move the corresponding plunger in the opposite direction within the corresponding housing to block the corresponding tube; generating a current curve of the at least one valve based on the corresponding measured current values of the at least one valve; generating a polynomial model of the at least one valve based on the corresponding current curve of the at least one valve; and applying the corresponding polynomial model to a trained classification model for the at least one valve to evaluate the deactivation state of the valve.

[0067] In a thirty-eighth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, the deactivation state indicates one of successful deactivation or failed deactivation, and the method further includes: generating an alert indicating a fault of the valve associated with the failed deactivation based on the deactivation state indicating failed deactivation.

[0068] In a thirty-ninth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, one or more non-transitory computer-readable media are provided that store instructions which, when executed by at least one processor, cause the at least one processor to: receive current values measured at a predetermined sampling rate for a predetermined duration during the enabling of at least one valve among a plurality of valves controlled by a control unit of a medical fluid system, where each valve includes a corresponding housing, a corresponding coil, and a corresponding plunger, where each valve is configured to enable the flow of medical fluid through a tube by energizing the corresponding coil to move the corresponding plunger within the corresponding housing, and where each valve is configured to close the flow of medical fluid through the tube by de-energizing the corresponding coil to move the corresponding plunger in the opposite direction within the corresponding housing to block the corresponding tube; generate a current curve for the at least one valve based on the corresponding measured current values of the at least one valve; generate a polynomial model for the at least one valve based on the corresponding current curve of the at least one valve; and apply the corresponding polynomial model to a trained classification model for the at least one valve to evaluate the enabling state of the at least one valve.

[0069] In a fortieth aspect of the present disclosure, which can be combined with any other aspect or parts thereof, the enabling state indicates one of successful enabling or failed enabling, and the non-transitory computer-readable media are further configured to: generate an alert indicating a fault of the valve associated with the failed enabling based on the enabling state indicating failed enabling.

[0070] In a forty-first aspect of the present disclosure, which can be combined with any other aspect or parts thereof, any features, functions, and alternatives described in Figures 1 to 14 any one or more of the figures can be combined with any features, functions, and alternatives described in Figures 1 to 14 any other figure.

[0071] According to the above aspects and the present disclosure set forth herein, an advantage of the present disclosure is to provide a medical fluid system with improved solenoid valve operation.

[0072] Another advantage of the present disclosure is to provide a medical fluid system having a solenoid valve method for reducing noise generated by valve operation.

[0073] Another advantage of the present disclosure is to provide a medical fluid system having a solenoid valve method for reducing noise without the need for additional equipment.

[0074] Yet another advantage of the present disclosure is to provide a medical fluid system having a solenoid valve method for ensuring proper opening and closing of the solenoid valve.

[0075] Another advantage of the present disclosure is to provide a medical fluid system having a solenoid valve method that ensures proper opening and closing of a solenoid valve without the need for additional equipment.

[0076] Additional features and advantages are described in the following detailed description and the drawings, and will be apparent from the following detailed description and the drawings. The features and advantages described herein are not all-inclusive, and in particular, given the drawings and description, many additional features and advantages will be apparent to those of ordinary skill in the art. Moreover, any particular embodiment need not have all of the advantages listed herein, and it is expressly contemplated to claim separately each advantageous embodiment. Additionally, it should be noted that the language used in this specification has been selected primarily for readability and guidance purposes, rather than to limit the scope of the inventive subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 is a cross-sectional schematic view of an embodiment of an automated PD system having solenoid valve operation of the present disclosure.

[0078] Figure 2 is a cross-sectional front view of an embodiment of a two-way valve that can be used with the system and related methods of the present disclosure.

[0079] Figure 3 is a cross-sectional front view of an embodiment of a three-way valve that can be used with the system and related methods of the present disclosure.

[0080] Figure 4 is a simulation diagram of a circuit of a system for reducing noise generated by solenoid valve operation in a medical fluid system using an NPN transistor according to a non-limiting embodiment of the present disclosure.

[0081] Figure 5 is a block diagram showing a system and method for reducing noise generated by solenoid valve operation in a medical fluid system using an NPN transistor according to a non-limiting embodiment of the present disclosure.

[0082] Figure 6 is a circuit diagram showing a system for reducing noise generated by solenoid valve operation in a medical fluid system using a MOSFET according to a non-limiting embodiment of the present disclosure.

[0083] Figure 7A is a graph showing control signals and applied voltages for a system for reducing noise generated by solenoid valve operation in a medical fluid system using a MOSFET according to a non-limiting embodiment of the present disclosure.

[0084] Figure 7BIs a graph showing the applied voltage for reducing the noise generated by the operation of a solenoid valve in a medical fluid system using pulse width modulation ("PWM") according to a non - limiting embodiment of the present disclosure.

[0085] Figure 8 Is a block diagram showing a system and method for reducing the noise generated by the operation of a solenoid valve in a medical fluid system using a MOSFET according to a non - limiting embodiment of the present disclosure.

[0086] Figure 9 Is a block diagram showing a system and method for reducing the noise generated by the operation of a solenoid valve in a medical fluid system using pulse width modulation ("PWM") according to a non - limiting embodiment of the present disclosure.

[0087] Figure 10A Is a current curve of a solenoid valve with successful enabling according to an exemplary embodiment of the present disclosure.

[0088] Figure 10B Is another current curve of a solenoid valve with successful enabling according to an exemplary embodiment of the present disclosure.

[0089] Figure 10C Is a current curve of a solenoid valve with successful disabling according to an exemplary embodiment of the present disclosure.

[0090] Figure 11 Is a flowchart of an example process for evaluating the function of solenoid valve enabling according to an exemplary embodiment of the present disclosure.

[0091] Figure 12 Is a sampled and normalized current curve of a solenoid valve with successful enabling according to an exemplary embodiment of the present disclosure.

[0092] Figure 13 Is a sampled and normalized current curve of a solenoid valve with failed enabling according to an exemplary embodiment of the present disclosure.

[0093] Figure 14 Is a flowchart of an example process for training a classification model for evaluating the function of solenoid valve enabling according to an exemplary embodiment of the present disclosure. Detailed Description

[0094] System overview

[0095] Now referring to the drawings and in particular Figure 1, shows an example system 10 incorporating the solenoid valve operation of the present disclosure. System 10 includes a dialysis machine 20, such as an automated peritoneal dialysis (“PD”) machine, and a control unit 100 having one or more processors 102, one or more memories 104, a video controller 106, and a user interface 108. The control unit 100 controls all of the current fluid flows and heating components of system 10 and receives the outputs from all of the sensors of system 10. The system 10 in the illustrated embodiment includes durable and reusable components that contact medical fluids, such as PD fluid, which requires the PD machine or cycler 20 to be disinfected, such as via heat disinfection, between treatments.

[0096] Figure 1 The system 10 in includes an in-line resistance heater 56, reusable supply lines or conduits 52a1 to 52a4 and 52b, a gas trap 60 operating with respective upper liquid level sensors 62a and lower liquid level sensors 62b, a gas trap valve 54d, an exhaust valve 54e positioned along the drain line 52e, a reusable line or conduit 52c, a dialysis fluid pump 70, temperature sensors 58a and 58b, pressure sensors 78a, 78b1, 78b2, a conduit or line 78c, reusable patient lines or conduits 52f and 52g having respective valves 54f and 54g, a double-lumen reusable patient line 28, a hose reel 80 for retracting the patient line 28, a reusable drain conduit or line 52i extending to the drain line connector 34 and having a drain line valve 54i, and reusable recirculation disinfection conduits or lines 52r1 and 52r2 operating with respective disinfection valves 54r1 and 54r2. A third recirculation or disinfection conduit or line 52r3 extends between disinfection connectors 30a and 30b for use during disinfection. A fourth recirculation or disinfection conduit or line 52r4 extends between disinfection connectors 30c and 30d for use during disinfection.

[0097] The system 10 also includes PD fluid containers or bags 38a to 38c (e.g., holding the same or different PD fluid formulations), which are respectively connected to the distal ends 24d of reusable PD fluid lines 24a to 24c. The system 10d also includes a fourth PD fluid container or bag 38d, which is connected to the distal end 24d of a reusable PD fluid line 24e. The fourth PD fluid container or bag 38d may contain the same or different types of PD fluid (e.g., icodextrin) as the PD fluid provided in the PD fluid containers or bags 38a to 38c. In one embodiment, the reusable PD fluid lines 24a to 24c and 24e extend through holes (not shown) defined or provided by the housing 22 of the cycler 20.

[0098] The system 10 in the illustrated embodiment includes four disinfection connectors 30a through 30d for connecting to the distal ends 24d of the reusable PD fluid lines 24a through 24c and 24e, respectively, during disinfection. The system 10 also provides a patient line connector 32 that includes a lumen, such as a U-shaped lumen, that directs fresh or used dialysis fluid from one PD fluid chamber of the dual-lumen reusable patient line 28 into the other PD fluid chamber. The reusable supply conduits or lines 52a1 through 52a4 are in fluid communication with the reusable supply lines 24a through 24c and 24e, respectively. The reusable supply conduits or lines 52a1 through 52a3 operate with valves 54a through 54c, respectively, to allow PD fluid from a desired PD fluid container or bag 38a through 38c to be drawn into the cycler 20. The three-way valve 94a in the illustrated example allows the control unit 100 to select between (i) 2.27% (or other) glucose dialysis fluid from container or bag 38b or 38c and (ii) icodextrin from container or bag 38d. In the illustrated embodiment, the icodextrin from container or bag 38d is connected to the normally closed port of the three-way valve 94a.

[0099] Figure 1 The system 10 is also shown to include and use a disposable filter kit 40 that is in fluid communication with the fresh and used PD fluid chambers of the dual-lumen reusable patient line 28. The disposable filter kit 40 includes a disposable connector 42 that connects to the distal end 28d of the reusable patient line 28. The disposable filter kit 40 includes a connector 48 that connects to the patient transfer kit. The disposable filter kit 40 also includes a sterilization-grade filter membrane 46 that further filters the fresh PD fluid.

[0100] In one embodiment, the system 10 is configured such that the drain line 52i is fluidly connected downstream of the dialysis fluid pump 70 during filling. In this way, if the drain valve 54i fails or leaks in some way during patient fill of patient P, the fresh PD fluid is pushed down the disposable drain line 36 rather than the used PD fluid potentially being drawn into the pump 70. In one embodiment, the disposable drain line 36 is removed for disinfection and the drain line connector 34 is capped via the cap 34c.

[0101] System 10 also includes a leak detection pan 82 located at the bottom of the housing 22 of the cycler 20 and a corresponding leak detection sensor 84 output to the control unit 100. In the example shown, system 10 is provided with an additional pressure sensor 78c upstream of the dialysate fluid pump 70, which allows measurement of the suction pressure of the pump 70 to assist the control unit 100 in more accurately determining the pump volume. The additional pressure sensor 78c in the illustrated embodiment is positioned along the exhaust line 52e, which may be filled with air or a mixture of air and PD fluid, but should still be at the same negative pressure as the PD fluid located within the PD fluid line 52c.

[0102] Figure 1 System 10 in the example includes redundant pressure sensors 78b1 and 78b2, where the output of one pressure sensor is used for pump control, as discussed herein, while the output of the other pressure sensor is a safety or watchdog output to ensure that the control pressure sensor is reading accurately. The pressure sensors 78b1 and 78b2 are positioned along a line that includes the third recirculation valve 54r3. In yet another example, system 10 may employ one or more intersections marked with an X in Figure 1 which may (i) reduce the total amount and volume of internal reusable tubing, (ii) reduce the number of valves required, and (iii) minimize the portion of the fluid circuit that is shared by fresh and used PD fluid.

[0103] Figure 1 System 10 in the example also includes an acid source, such as a citric acid container or bag 66. The citric acid container or bag 66 is selectively in fluid communication with the second three-way valve 94b via a citric acid valve 54m positioned along the citric acid line 52m. In one embodiment, the citric acid line 52m is connected to a normally closed port of the second three-way valve 94b to provide a redundant valve between the citric acid container or bag 66 and the PD fluid circuit during treatment. The redundant valve ensures that no citric acid (or other) reaches the treatment fluid line during treatment. Citric (or other) acid is alternatively used during disinfection.

[0104] It should be understood that system 10 does not need to (i) be a dialysis system, or (ii) use redundant or durable components that are disinfected between uses to employ the sensor thermoelectric heating of the present disclosure. System 10 may alternatively be any type of medical fluid system and may employ a disposable kit having a disposable pumping portion that contacts the corresponding medical fluid. In the main example described herein, solenoid valves are described as operating with a PD machine or cycler 20.

[0105] Any one or more or all of valves 54a to 54h, 54m and 54r1 to 54r4, 94a and 94b can be solenoid valves, which can be of the type that uses an internal fluid path that opens or closes depending on whether the coil is energized. This type of solenoid valve is well-suited for durable or reusable versions of PD machines or cyclers. Another type of solenoid valve for valves 54a to 54h, 54m and 54r1 to 54r4 operates by not closing or closing a flexible tube depending on whether the coil is energized. This type of solenoid valve is well-suited for versions of PD machines or cyclers that operate with a disposable kit, but can also be used with durable versions of PD machines or cyclers, which will have internal flexible tubing for operating with the solenoid valve.

[0106] Now referring to Figure 2 , a suitable two-way solenoid valve 154 for two-way valves 54a to 54h, 54m and 54r1 to 54r4 is shown. Figure 2 The valve 154 is of the type that uses an internal fluid passage that opens or closes depending on whether the coil is energized. The valve 154 includes two main sections, namely an electromagnetic section 160 and a valve section 180. The electromagnetic section 160 includes an electromagnetic housing 162. The electromagnetic housing 162 supports a coil 164 that extends around the inner wall 162i of the housing 162 and is energized to move or translate an electromagnetic plunger 166. A compression spring 168 is provided and positioned to bias the plunger 166 to a closed position when energy is removed from the coil 164.

[0107] Figure 2 It is shown that the plunger 166 has a contact end 166e. Also, a stop 162s is provided on the core 162c of the electromagnetic housing 162. When the coil 164 is energized, a magnetic field is induced, causing the electromagnetic plunger 166 to translate from right to left within the inner wall 162i of the housing 162 such that the contact end 166e of the plunger 166 abuts the stop 162s to provide a travel end point for the plunger 166 in the valve open position. The abutting contact of the end 166e with the stop 162s causes noise, which can be a problem for PD patients, especially when the patient is trying to sleep. Structures and related methods that help reduce the noise caused by the abutting contact of the end 166e with the stop 162s are described herein.

[0108] Figure 2Shows a two-way solenoid valve 154 in a closed state or a state without fluid flow. Here, the coil 164 is de-energized, such that the compression spring 168 pushes the contact end 166e of the plunger 166 away from the stop 162s provided at the core 162c of the solenoid housing 162. The lever end 166l of the plunger 166 translates, such that the lever 170 rotatably held at the lever end 166l of the plunger 166 tilts to close the fluid path located within the valve section 180 of the valve 154.

[0109] The valve section 180 of the valve 154 includes a valve housing 182. The valve housing 182 defines a fluid inlet 184 and a fluid outlet 186. The portion of the lever 170 extending into the valve housing 182 is fitted with a membrane or a plug 188, which may be made of a medically safe compressible (sealable) rubber such as silicone. In Figure 2 the closed position, where the coil 164 is de-energized and the compression spring 168 is extended, the lever 170 pivots the diaphragm or the plug 188 to contact and seal, for example, the inclined port 186p inside the outlet 186 to prevent fluid flow. When the coil 164 is energized, the plunger 166 moves leftward to compress the spring 168 and pivot the lever 170, such that the membrane or the plug 188 moves away from the inclined port 186p of the outlet 186 and stops in a substantially vertical position. Here, a fluid such as water or PD fluid can flow from the fluid inlet 184 around the membrane or the plug 188 and through the fluid outlet 186.

[0110] When the valve 154 is closed and the membrane or the plug 188 is sealed against the inclined port 186p of the fluid outlet 186, the fluid pressure downstream of the outlet 186 is less than the fluid pressure upstream of the fluid inlet 184. The pressure increment helps to seal the membrane or the plug 188 against the inclined port 186p, such that the compression spring 168 does not need to provide the force (or all of the required forces) required to keep the membrane or the plug sealed against the inclined port. The main function of the compression spring 168 is to translate the plunger 166 when the coil 164 is de-energized. However, it should be understood that the pressure increment that helps to seal the membrane or the plug 188 against the inclined port 186p when the valve 154 is closed also resists the magnetic force generated when the coil 164 is energized. Structures and related functions for ensuring that the valve 154 opens correctly when it is supposed to be opened are described herein.

[0111] Now referring to Figure 3 , shows a suitable three-way solenoid valve 194 for three-way valves 94a, 94b. Figure 3The valve 194 is of the type that uses an internal fluid passageway that opens or closes depending on whether the coil is energized. Similar to valve 154, valve 194 includes two main sections, namely an electromagnetic section 200 and a valve section 220. The electromagnetic section 200 is substantially the same as the electromagnetic section 160 of valve 154. The electromagnetic section includes an electromagnetic housing 202 that supports a coil 204, and the coil 204 is energized to move or translate an electromagnetic plunger 206. A compression spring 208 is provided and positioned to bias the plunger 206 to a closed position when energy is removed from the coil 164. The plunger 206 has a contact end 206e that abuts a stop 202s disposed at the core 202c of the electromagnetic housing 202 when the coil 204 is energized. The abutting contact of the end 206e with the stop 202s causes noise, which can be a problem for PD patients, especially when the patient is trying to sleep. Structures and related methods are described herein that help reduce the noise caused by the abutting contact of the end 206e with the stop 202s.

[0112] Figure 3 Shown is a three-way solenoid valve 194 in a normally closed state. Here, the coil 204 is not energized, such that the compression spring 208 pushes the contact end 206e of the plunger 206 away from the stop 202s disposed at the core 202c of the electromagnetic housing 202. The lever end 206l of the plunger 206 translates such that a lever 210 rotatably held at the lever end 206l of the plunger 206 tilts to close a fluid path located within the valve section 220 of the valve 194.

[0113] The valve section 220 is where the three-way valve 194 differs from the two-way valve 154. The valve section 220 includes a valve housing 222 that defines a fluid inlet 224, a normally closed fluid outlet 226, and a normally open fluid outlet 228. The portion of the lever 210 that extends into the valve housing 222 is fitted with a membrane or plug 230, which can again be made of a medically safe compressible (sealable) rubber such as silicone. Figure 2its normally-closed position, where the coil 204 is de-energized and the compression spring 208 is extended, and the lever 210 pivots the diaphragm or plug 230 to contact and seal the internal (e.g., inclined) port 226p of the normally-closed fluid outlet 226, thereby preventing fluid from flowing through the normally-closed outlet. When the coil 204 is energized, the plunger 206 moves leftward to compress the spring 208 and pivot the lever 210 such that the diaphragm or plug 230 moves away from the inclined port 226p of the normally-closed fluid outlet 226 and instead contacts and seals the internal (e.g., inclined) port 228p of the normally-open fluid outlet 228, thereby preventing fluid from flowing through the normally-open outlet. In the normally-closed state, the three-way valve 194 allows fluid such as water or PD fluid to flow from the fluid inlet 224 through the normally-open fluid outlet 228. In the normally-open state, the three-way valve 194 allows fluid such as water or PD fluid to flow from the fluid inlet 224 through the normally-closed fluid outlet 228.

[0114] The higher fluid pressure through the fluid inlet 224 helps to seal the diaphragm or plug 230 against both the normally-closed port 226p and the normally-open port 228p, where the pressure in the normally-closed fluid outlet 226 and the normally-open fluid outlet 228 is less. However, it should be understood that the pressure increment that helps to seal the diaphragm or plug 230 against the inclined ports 226p, 228p also counteracts (i) the magnetic force induced when the coil 164 is energized to open the normally-closed fluid outlet 226, and (ii) the force of the compression spring 208 when the coil 164 is de-energized to open the normally-open fluid outlet 226. Structures and related functions for ensuring that the normally-closed fluid outlet 226 opens correctly when it should be are described herein.

[0115] Solenoid valve method for noise reduction

[0116] As previously discussed, reliable methods for reducing the noise caused by solenoid valves in medical fluid delivery operations are desirable and needed. Noise reduction is particularly relevant for peritoneal dialysis systems, which operate close to the patient and may occur during the night when the patient is sleeping, and reduced noise is crucial. A desirable PD system is one in which the noise level is kept below 33 decibels. Various embodiments of the present disclosure describe systems and methods for using solenoid valves to reduce noise in PD systems. In particular, various embodiments describe systems and methods for controlling the movement of the solenoid valve to minimize the amount of sound (noise) that occurs upon impact during the activation and deactivation of the valve. The system and method generally include slowing the movement of the valve plunger within the valve coil. Any modification that slows the movement of the valve will result in a smaller impact with the valve housing and produce a lower level of impact sound. Various embodiments discussed herein include the use of low-pass filtering, NPN transistors, MOSFETs, and pulse width modulation, among others.

[0117] In at least one embodiment, a method of slowing the movement of a valve plunger involves ramping up the voltage applied to an electromagnetic coil (e.g., during valve actuation) and / or ramping down the voltage applied to the electromagnetic coil (e.g., during valve deactuation). In one aspect, a low-pass filter can be applied to an existing application of voltage to provide the ramping up and / or ramping down effect. Since the steady-state operation of the valve typically uses about 0.3 A in one example, the resistor may need to be small and the capacitor may need to be large. For example, if a 1-ohm resistor is selected, the size of the capacitor to obtain a time constant of about 25 ms can be about 25 mF.

[0118] In at least one embodiment, a transistor can be used to ramp up and / or ramp down the voltage applied to the electromagnetic coil of a valve in order to slow the movement of the plunger and reduce noise. In some aspects, the transistor can provide linear control of the voltage applied to the coil. Different variants of the transistor (e.g., NPN-transistor, MOSFET-transistor, etc.) can provide different capabilities and advantages to effectively reduce the noise of the solenoid valve, which will be discussed in conjunction with Figures 4 to 8 below.

[0119] Figure 4 is a simulation diagram of a circuit of a system for reducing noise generated by the operation of a solenoid valve in a medical fluid system according to a non-limiting embodiment of the present disclosure. The system can include a valve 414 of a PD system (e.g., valve 154 or valve 194 discussed above) electrically controlled by an NPN transistor 412. For example, as Figure 4As shown, a power supply 406 (e.g., of an NPU) can control an NPN - transistor 412 via a control signal (e.g., an ON / OFF signal). The control signal can be generated based on a power - voltage setting 404. The control signal sent to the NPN - transistor can include and / or generate an input current to the NPN - transistor (e.g., as shown by current - ramp curve 402). The input current can cause the NPN transistor to switch valve 414 to apply a voltage to an electromagnetic coil. If the input current remains low (e.g., such that the input current does not exceed the non - saturation region of NPN transistor 412), the voltage applied to the electromagnetic coil can ramp up with the current of NPN transistor 412 (e.g., as shown by current - ramp curve 402). This behavior is similar to a low - pass filter without the need to provide significant capacitance or resistance for the electromagnetic coil. In some embodiments, the system can further include a solver device 408 that is configured to determine when to provide the necessary signal to NPN transistor 412 to ramp up or ramp down the voltage applied to the electromagnetic coil. Simulation of the circuit can result in effects in the physical domain (e.g., via valve 414). For example, NPN - transistor 412 can cause valve 414 to apply a force on a plunger and cause movement of the plunger.

[0120] Figure 5 is a block diagram showing a system and method for using an NPN transistor to reduce noise generated by solenoid - valve operation in a medical fluid system according to non - limiting embodiments of the present disclosure. As described above, the system can include a control unit 100 of the PD system 10, which can further include a memory 102 and a processor 104. The system can also include a plurality of NPN transistors 504 that are configured to control a plurality of valves 510 (e.g., valve 154 or valve 194 discussed above) in response to control signals received from the control unit 100. As described above, the plurality of valves 510 can include solenoid valves (e.g., valve 154 or valve 194) used by the PD system to control the flow of fluids such as fresh and used PD fluids. Thus, each valve 510 can include a corresponding housing 514, a corresponding electromagnetic coil 512, and a corresponding plunger 516. Each valve 510 can be configured to enable fluid flow through a tube of the PD system by applying a voltage to the corresponding electromagnetic coil 512 via the corresponding NPN transistor 504 to move the corresponding plunger 516 within the corresponding housing 514. Each valve can also be configured to close the fluid flow through the tube by not applying (e.g., reducing) the voltage to the corresponding coil 512 via the corresponding NPN transistor 504 to move the corresponding plunger 516 in an opposite direction to the corresponding housing 514 (e.g., to block the corresponding tube).

[0121] To reduce the noise associated with the actuation of a given valve (e.g., opening of the valve), the control unit 100 can be configured to send a low control signal to the NPN transistor 504 associated with the valve 510 (block 502) (e.g., by processing computer-executable instructions stored in the memory 102 via the processor 104). The low control signal can cause the input current to the NPN transistor 504 to ramp up (block 506). The ramp up of the input current to the NPN transistor 504 can cause a corresponding ramp up in the voltage applied to the coil 512 of the valve 510 (block 508). As previously described, the ramp up in the voltage applied to the electromagnetic coil 512 (e.g., as opposed to a sudden voltage application) causes the plunger 516 to move more slowly during actuation. Thus, the slower movement can reduce the sound generated by the corresponding plunger of the valve 510 (block 518).

[0122] To reduce the noise associated with the deactuation of a given valve (e.g., closing of the valve), the control unit 100 can be configured to turn off the low control signal to the NPN transistor 504 associated with the valve (block 520). The turn off of the control signal can cause a ramp down in the input current supplied to the NPN transistor 504 (block 522). The ramp down in the input current to the NPN transistor 504 can cause a corresponding ramp down in the voltage applied to the coil 512 of the valve 510 (block 524). As previously described, the ramp down in the voltage applied to the electromagnetic coil 512 (e.g., as opposed to a sudden termination of the voltage) causes the plunger 516 to move more slowly in the opposite direction during deactuation. Thus, the slower movement can reduce the sound generated by the corresponding plunger of the valve 510 (block 526).

[0123] A MOSFET is another type of transistor that can be used to slow down the movement of the plunger in a solenoid valve, thereby reducing noise. Additionally, using a MOSFET to control the voltage applied to the electromagnetic coil can overcome the unwanted heat caused by the relatively high resistance in an NPN transistor.

[0124] Figure 6A circuit diagram of a system for reducing noise generated by the operation of a solenoid valve in a medical fluid system using MOSFETs according to a non - limiting embodiment of the present disclosure. Using P - channel MOSFETs 614a and 614b, the circuit of the system can facilitate a slow application of voltage (e.g., by ramping up) to the electromagnetic coil 605 of the valve 604, and a slow removal of voltage (e.g., by ramping down) from the electromagnetic coil 605 of the valve 604. The control signal 602 can include a simple digital output from the control unit 100 and / or other digital circuits. When the digital control signal is high (e.g., “1” and / or “true”), one or both of the MOSFETs 614a and 614b can cause a ramp - up of the voltage applied to the electromagnetic coil 605 until the applied voltage reaches the same voltage as the input voltage V in of the valve 604. In some aspects, the voltage V in can refer to the threshold voltage required for the valve to be fully enabled (e.g., by moving the plunger completely to the end point within the housing). If the digital control signal generated by the control unit 100 goes low (e.g., “0” or “false”), the applied voltage can slowly ramp down towards a voltage of 0V. The ramp - up and ramp - down times can be adjusted by changing the values of one or more resistors and capacitors in the circuit (e.g., resistors R2 606, R4 608, and R5 610, and capacitor C1 612). In some aspects, one or more resistors and / or one or more capacitors can be arranged in series, for example, as shown in the circuit of Figure 6 . The ramp - up and ramp - down of the voltage applied to the electromagnetic coil 605 can add turn - on and turn - off delays, respectively, to the control of the electromagnetic coil 605. To shorten this delay, an initial ramp - offset circuit can be added to the circuit to generate an additional voltage of an offset value to be applied to the coil 605. The offset value can be set to a voltage close to the lowest voltage applied to the electromagnetic coil 605 by one or more of the MOSFETs 614a, 614b. In one embodiment, the offset value of the ramp - offset voltage can be set by adjusting the feedback resistor R5 610 relative to the resistors R2 606 and R4 608. Example control signals sent to MOSFET 614b and example voltages applied to the electromagnetic coil 605 can be seen in Figure 7A .

[0125] Figure 7Ais a graph showing a control signal 704 and an applied voltage 702 according to a non - limiting embodiment of the present disclosure, the control signal 704 and the applied voltage 702 being used to reduce the noise generated by the operation of the solenoid valve of the medical fluid system 10 using a MOSFET. As previously described, the control signal 704 can be a digital signal generated by the control unit 100 and can be sent to the MOSFET to cause the MOSFET to generate the applied voltage 704. As Figure 7A shown, the high level (i.e., the power level) of the digital control signal 704 is 3V, while the low level (i.e., the reference level) of the digital control signal is 0V. In response to the high digital control signal 704, the MOSFET allows the applied voltage 702 to ramp up (as shown by the positive slope from approximately 0 ms to approximately 210 ms). However, when the digital control signal 704 is set to the low level (e.g., 0V), the MOSFET causes the applied voltage 702 to ramp down (as shown by the negative slope from approximately 500 ms to 650 ms). The relatively vertical increase and decrease of the applied voltage 702 (at 0 ms and 500 ms respectively) can be caused by an offset voltage applied to the electromagnetic coil to overcome the delays caused by the ramp - up and ramp - down respectively.

[0126] Figure 7B is a graph showing an applied voltage for reducing the noise generated by the operation of a solenoid valve in a medical fluid system using pulse - width modulation ("PWM") according to a non - limiting embodiment of the present disclosure. The applied voltage can respond to a control signal (e.g., control signal 705) generated by the control unit 100 and received by an input / output (I / O) driver associated with the solenoid valve to energize (e.g., enable) the solenoid valve. In response to this command, the I / O driver can apply a PWM voltage to the electromagnetic coil associated with the valve and cause the PWM voltage to ramp up 706. For example, the I / O driver can ramp the PWM voltage from approximately 6V to 24V within 2 ms to 400 ms. The applied voltage can cause the plunger of the valve to move towards the housing. After the plunger in the valve has reached its end point (e.g., within the housing) (e.g., as may occur at or before the stage indicated as "impact" 708), the PWM duty cycle can be reduced, which reduces the power consumption and heat generation in the PD system 10. For example, the control unit 100 can command (e.g., via a second control signal) the I / O driver to cause the PWM signal applied to the corresponding coil to ramp down until a predetermined voltage is reached. For example, the I / O driver can maintain the PWM signal at 12V (e.g., as Figure 7B shown by the "hold" 710 from 600 ms to 1200 ms). When the valve is to be de - energized (e.g., closed and / or shut off), the I / O driver can ramp the PWM down 712 to 0V (e.g., as Figure 7BAs shown, between 1200 ms and 1400 ms). In some embodiments, if the I / O driver ramps up the PWM voltage as indicated, the plunger in the valve can reach its end point within the housing during the ramp-up phase 706. Since the plunger may hit the end point due to the lower power applied to the solenoid valve, the sound level associated with hitting the end point may be low. Additionally, the full power level of the phase indicated as "impact" 708 can ensure that the plunger hits the seal, even if the load has increased. After this phase, the power consumption can be reduced (e.g., as in the "hold" phase 710).

[0127] Figure 8 is a block diagram showing a system and method for reducing noise generated by the operation of solenoid valves in a medical fluid system using MOSFETs according to non-limiting embodiments of the present disclosure. As described above, the system can include a control unit 100 of the PD system 10, which can further include a memory 102 and a processor 104. The system can also include a plurality of MOSFETs 804 configured to control a plurality of valves 510 in response to digital control signals received from the control unit 100. As described above, the plurality of valves 510 can include solenoid valves 154, 194 ( Figure 2 and Figure 3 ) used by the PD system 10 to control fresh and used PD fluid flow. Thus, each valve 510 can include a corresponding housing 514, a corresponding electromagnetic coil 512, and a corresponding plunger 516. Each valve 510 can be configured to enable fluid flow through the tubing of the PD system 10 by applying a voltage to the corresponding electromagnetic coil 512 via the corresponding MOSFET 804 to move the corresponding plunger 516 within the corresponding housing 514. Each valve can also be configured to close the fluid flow through the tubing by not applying (e.g., reducing) the voltage to the corresponding coil 512 via the corresponding MOSFET 804 to move the corresponding plunger 516 in a direction opposite to the corresponding housing 514 (e.g., to occlude the corresponding tubing).

[0128] To reduce the noise associated with the valve actuation (e.g., opening of the valve) of a given valve, the control unit 100 may be configured to (e.g., by the processor 104 processing computer-executable instructions stored in the memory 102) send a high digital control signal (e.g., a digital signal corresponding to a “high” level, a power supply voltage, and / or a binary output of “1”) to the MOSFET 804 associated with the valve 510 (block 802). It should be understood that, unlike an NPN transistor, a MOSFET requires less power to operate the gate (e.g., actuate the MOSFET), and thus may not require the input current to ramp up as in the case of an NPN transistor. The high control signal may cause the MOSFET 804 to apply and ramp up a voltage to the corresponding coil 512 of the valve 510 (block 806). As previously described, the ramping up of the voltage applied to the electromagnetic coil 512 (e.g., as opposed to a sudden voltage application) causes the plunger 516 to move more slowly during actuation. Thus, the slower movement can reduce the sound generated by the corresponding plunger of the valve 510 (block 810). In some embodiments, the slow ramping up of the voltage applied to the coil may result in an undesirable delay in the actuation of the valve. Thus, an offset voltage may also be applied to the electromagnetic coil 512 via a ramp offset circuit (block 808).

[0129] To reduce the noise associated with the valve de-actuation (e.g., closing of the valve) of a given valve, the control unit 100 may be configured to send a low digital control signal (e.g., a digital signal corresponding to a “low” level, a reference or ground voltage, and / or a binary output of “0”) to the MOSFET 804 associated with the valve (block 812). The low control signal may cause the MOSFET 804 to apply a ramping down voltage to the corresponding coil 512 of the valve 510 (block 814). As previously described, the ramping down of the voltage applied to the electromagnetic coil 512 (e.g., as opposed to a sudden removal of the voltage) causes the plunger 516 to move more slowly during de-actuation. Thus, the slower movement can reduce the sound generated by the corresponding plunger of the valve 510 (block 818). In some embodiments, the slow ramping down of the voltage applied to the coil may result in an undesirable delay in the de-actuation of the valve. Thus, the offset voltage may also be released from the electromagnetic coil 512 via a ramp offset circuit (block 816).

[0130] In at least one embodiment, pulse width modulation (“PWM”) can be used to ramp up and / or ramp down the voltage applied to the solenoid coil of the valve in order to slow down the movement of the plunger and reduce noise. Additionally, techniques employing PWM can overcome problems caused by relying on a transistor to gradually lower (e.g., ramp down) the voltage applied to the solenoid coil during deactivation. For example, reducing the applied voltage can induce a lower magnetic field in the solenoid coil, resulting in a smaller force acting on the plunger. Since the valve can operate against low or high pressures, the valve may need full force to go from closed to open during activation, or from open to closed during deactivation. Systems and methods that rely on PWM signals for valve activation and deactivation can overcome these problems. Additionally, as discussed herein, controlling the activation and / or deactivation of the valve by relying on a pulse width modulation method can also involve ramping up and / or ramping down the voltage applied to the solenoid coil, but only during the transition period. After the transition period (e.g., during the start of valve activation or deactivation), the pulse width modulation technique can involve finally applying the full input voltage V in for a duration to ensure that the plunger moves properly to the desired end point (e.g., inside the housing during activation and towards the position blocking the valve during deactivation).

[0131] The application of PWM for valve activation can involve applying a pulsed voltage (rapidly switching on / off) to the solenoid coil while ramping up the application until the plunger has moved. The application of PWM for valve deactivation may involve reducing the pulsed voltage applied to the solenoid coil while ramping down the application until the plunger has moved. This can allow for slower movement of the plunger, lower shock during valve activation / deactivation, and thus reduced noise. Another benefit of this method is that PWM is also available during normal operation. Thus, using PWM for valve activation and / or deactivation can reduce the total power requirement and keep the PD system 10 cooler during operation.

[0132] In at least one embodiment, an example power-on / off cycle for a solenoid valve utilizing PWM involves the control unit 100 sending a command (e.g., via a control signal) to an input / output (I / O) driver associated with the valve to power on (e.g., enable) the valve. In response to the command, the I / O driver can apply and ramp up a PWM voltage to the electromagnetic coil associated with the valve. For example, the I / O driver can ramp up the PWM voltage from 0% to 100% within 2 ms to 75 ms (e.g., 2 ms to 10 ms). Applying the voltage can cause the plunger of the valve to move towards the housing. After the plunger in the valve has reached its end point (e.g., within the housing), the PWM duty cycle can be decreased, which can reduce power consumption and heat generation in the PD system 10. For example, the control unit 100 can command (e.g., via a second control signal) the I / O driver to ramp down the PWM signal applied to the corresponding coil to a duty cycle of 25% or higher (e.g., 50% or higher). When the valve is to be deactivated (e.g., closed and / or shut off), the I / O driver can ramp down the PWM (e.g., from 50%) to 0% within 25 ms to 75 ms (e.g., approximately 50 ms).

[0133] Figure 9 is a block diagram showing a system and method for reducing noise generated by the operation of solenoid valves in a medical fluid system using pulse width modulation (“PWM”) in accordance with non-limiting embodiments of the present disclosure.

[0134] As described above, the system can include a control unit 100 of the PD system 10, which can further include a memory 102 and a processor 104. The system can also include a plurality of input / output (“I / O”) nodes 904 (also referred to as I / O drivers), which are configured to control a plurality of valves 510 in response to control signals received from the control unit 100. As described above, the plurality of valves 510 can include solenoid valves 154, 194( Figure 2 and 3 ), which are used by the PD system 10 to control fresh and used PD fluid flow. Thus, each valve 510 can include a corresponding housing 514, a corresponding electromagnetic coil 512, and a corresponding plunger 516. Each valve 510 can be configured to enable fluid flow through the tubing of the PD system 10 by applying a voltage to the corresponding electromagnetic coil 512 via the corresponding I / O node 904 to move the corresponding plunger 516 within the corresponding housing 514. Each valve can also be configured to close the fluid flow through the tubing by not applying (e.g., reducing) the voltage to the corresponding coil 512 via the corresponding I / O node 904 to move the corresponding plunger 516 in a direction opposite to the corresponding housing 514 (e.g., to occlude the corresponding tubing).

[0135] To reduce the noise associated with the valve actuation (e.g., opening of the valve) of a given valve, the control unit 100 may be configured to (e.g., by the processor 104 processing computer-executable instructions stored in the memory 102) send a control signal to the I / O node associated with the valve (block 902). The control signal may be a digital or an analog signal. The control signal (referred to as the first control signal to distinguish it from subsequent control signals discussed herein) may command the I / O node 904 to apply and ramp up a PWM signal (e.g., voltage) to the electromagnetic coil 512 of the valve 510 (block 906). For example, the I / O node may ramp up the duty cycle of the pulsed voltage applied to the corresponding coil from 0% to 100% in about 50 ms. The ramp up of the voltage applied to the electromagnetic coil 512 (e.g., as opposed to a sudden voltage application) causes the plunger 516 of the valve 510 to move more slowly during actuation. Thus, the slower movement may reduce the sound generated by the corresponding plunger of the valve 510 (block 908). After the plunger 516 reaches the end position (e.g., within the housing 514) during valve actuation, the control unit 100 may send a second control signal to the I / O node 904 (block 910). The second control signal may cause the I / O node to ramp down the PWM signal to the corresponding coil (block 912). For example, the duty cycle may be ramped down (e.g., from 100%) to a duty cycle of at least 25% (e.g., about 50%) of V in The ramp down at block 912 may help save power in the PD system 10.

[0136] To reduce the noise associated with the deactivation of a given valve (e.g., closing of the valve), the control unit 100 may be configured to send a third control signal to the I / O node 904 associated with the valve (block 914). The third control signal, which may include a digital or analog signal, may cause the I / O node 904 to cause a ramp-down of a PWM signal (e.g., voltage) applied to the corresponding coil 512 of the valve 510 (block 814). For example, the ramp-down of the PWM duty cycle may reduce the duty cycle to 0%. In some embodiments, the ramp-down to 0% may occur between 25 and 75 ms (e.g., within about 50 ms). The ramp-down of the voltage applied to the electromagnetic coil 512 (e.g., as opposed to a sudden removal of the voltage) causes the plunger 516 to move more slowly during deactivation. Thus, the slower movement may reduce the sound generated by the corresponding plunger of the valve 510 (block 918). In some embodiments, one or more capacitors may be arranged in series between the control unit 100 and the I / O node 904. The duration of the ramp-up and / or ramp-down of the PWM signal may be based on the capacitance value of the corresponding one or more capacitors. Additionally or alternatively, one or more resistors may be arranged in series between the control unit 100 and the I / O node 904. The duration of the ramp-up and / or ramp-down of the PWM signal may be based on the resistance value of the corresponding one or more resistors.

[0137] Evaluating functions enabled by solenoid valves

[0138] As previously discussed, there is a desire and need for a reliable method to verify whether solenoid valves used in PD systems and cyclers (as well as other medical fluid systems and machines), such as valves 154, 194 ( Figure 2 and Figure 3 ) are functionally enabled (e.g., properly opened when powered on). In the absence of such verification systems and methods, dangerous situations may occur. For example, if the machine is operating in one mode (e.g., with valves 154, 194 open and fluid flowing) while the valves are configured in another mode (e.g., valves 154, 194 actually closed and no fluid flowing), the PD system 10 may malfunction, resulting in the cessation of treatment. As discussed herein, the functionality of the solenoid valves 154, 194 (e.g., whether the valves are properly enabled) can be determined by analyzing the current drawn by the electromagnets operating the valves when enabled. A trained classification model may be applied to the current curve to distinguish between solenoid valves 154, 194 that are properly powered on and thus successfully enabled and those that are unsuccessfully enabled.

[0139] In some embodiments, the same methods discussed for ensuring that valves 154, 194 are being properly enabled or opened can be used to verify that solenoid valves are being functionally deactivated (e.g., properly closed when power is removed). For example, a current profile of the electromagnet operating the valves 154, 194 when commanded to deactivate can be received. A classification model can be trained to identify current profiles associated with successful valve deactivation from current profiles associated with unsuccessful valve deactivation. The trained classification model can be applied to the current profile of the electromagnet commanded to deactivate to determine whether solenoid valves 154, 194 have been functionally deactivated or closed.

[0140] Figure 10A is a current profile of a solenoid valve, such as valves 154, 194 ( Figure 2 and Figure 3 ) with successful enabling according to an exemplary embodiment of the present disclosure. Additionally, Figure 10A plots the current over time of the electromagnetic coils 164, 204 in the solenoid valves when the electromagnetic coils are energized during the enabling of solenoid valves 154, 194 (e.g., for opening of the solenoid valves). This plot indicates current measurements taken at frequent intervals (e.g., at a frequency of approximately 5 kHz). As Figure 10A shows, successful enabling of solenoid valves 154, 194 causes the current to initially peak (e.g., at position 1002a) before starting to decline. The initial peak and subsequent decline are due to the plungers 166, 206 of solenoid valves 154, 194 entering the magnetic field of the electromagnetic coils 164, 204 as the plungers move in the direction towards the housing of the solenoid valves. The movement of the plungers 166, 206 through the magnetic field of the electromagnetic coils 164, 204 generates an opposing voltage that "interrupts" the rise of the current through the electromagnetic coils, causing the current to decline after the initial peak 1002a. The plungers 166, 206 hit the end point of their movement (e.g., by resting against the housing of the solenoid valves) at approximately 22 ms, as shown by position 1004a in Figure 10A . The stopping of the movement of the plungers 166, 206 causes the earlier generated opposing voltage to stop, causing the current to rise again, as shown by the rise 1006a in Figure 10A . Thus, to verify that the plungers 166, 206 have moved and, therefore, that the solenoid valves 154, 194 have indeed opened when enabled, the current profile needs to indicate a "low point" 1004a at approximately 22 milliseconds, for example. If the plungers 166, 206 do not move, the current profile can resemble a regular "RC - curve", i.e., where no low point appears.

[0141] Figure 10B is a current profile of a solenoid valve (e.g., valves 154, 194 ( Figure 2 and Figure 3)) second different current curve. Similar to Figure 10A , Figure 10B 's graph plots the variation of the current in the electromagnetic coils 164, 204 in the solenoid valves 154, 194 over time when the electromagnetic coils are energized during the actuation of the solenoid valves (e.g., for opening the solenoid valves). As previously described, the successful actuation of the solenoid valves 154, 194 causes the current to initially reach a peak (e.g., at position 1002b) before starting to decline. The initial peak and subsequent decline are due to the fact that when the plungers 166, 206 of the solenoid valves 154, 194 move in the direction towards the housing of the solenoid valves, the plungers 166, 206 of the solenoid valves 154, 194 enter the magnetic field of the electromagnetic coils 164, 204. The movement of the plungers 166, 206 through the magnetic field of the electromagnetic coils 164, 204 generates an opposing voltage that "interrupts" the rise of the current through the electromagnetic coils, causing the current to decline after the initial peak 1002b. Here, the plungers 166, 206 hit the end point of their movement at approximately 60 ms (e.g., by resting against the housing of the solenoid valves 154, 194), as shown at Figure 10B 's position 1004b. The stop of the movement of the plungers 166, 206 causes the earlier generated opposing voltage to stop, resulting in the current rising again, as shown by the rise 1006b in Figure 10B . Figure 10A and 10B The difference in the current curves between the graphs can be based on the type of sensor used, and / or on one or more parameters, configurations, and / or characteristics of the sensor used.

[0142] Figure 10C is the current curve of a solenoid valve with successful deactivation according to an exemplary embodiment of the present disclosure (e.g., valves 154, 194 ( Figure 2 and Figure 3 ))). Figure 10C 's graph plots the variation of the current in the electromagnetic coils 164, 204 in the solenoid valves 154, 194 over time when the electromagnetic coils are de-energized during the deactivation of the solenoid valves (e.g., for closing the solenoid valves). As Figure 10CAs shown, the successful deactivation of solenoid valves 154, 194 causes the current to initially reach a local minimum (e.g., at position 1002c) before starting to rise. The local minimum and subsequent rise are due to the fact that when the plungers 166, 206 of solenoid valves 154, 194 move in a direction away from the housing of the solenoid valves, the plungers 166, 206 of solenoid valves 154, 194 move out of the magnetic field of the electromagnetic coils 164, 204. Before the current rises again, the movement of the plungers 166, 206 away from the magnetic field of the electromagnetic coils 164, 204 reduces the voltage that causes the current through the electromagnetic coils to drop, resulting in the local minimum 1002c. After the plungers 166, 206 leave the housing, they hit the end point of their movement and close the tube at approximately 90 ms, as Figure 10C shown at position 1004c. The stopping of the movement of the plungers 166, 206 causes the current to drop again, as Figure 10C shown by the drop 1006c in

[0143] Figure 11 is a flowchart of an example process 1100 for evaluating the functionality of solenoid valve activation according to an exemplary embodiment of the present disclosure. Process 1100 can be executed by a computing system having one or more processors. Additionally, the processor and / or computing system can execute process 1100 based on computer-executable instructions stored in the memory of the computing system. As will be used and discussed for purposes of explanation, the computing system can include the control unit 100 of the PD system 10, which includes one or more processors 102 and one or more memories 104.

[0144] Process 1100 can begin with the PD system 10 activating one or more valves 154, 194 ( Figure 2 and Figure 3 ) to start the flow of current (block 1102). For example, during normal operation of the PD system 10, one or more valves 154, 194 can be commanded to be activated to allow fluid to flow through the tubes associated with the valves. Additionally or alternatively, during a time period when the PD system 10 is not servicing a patient (e.g., during a pre-treatment or pre-conditioning period of the PD system 10), the control unit 100 can (e.g., by sending an electronic signal command) cause the valves 154, 194 of the PD system 10 to be activated. However, as will be discussed, for example, if a valve fails, causing or commanding the valves 154, 194 to be activated may not necessarily actuate the valve to open. As discussed herein, process 1100 discloses one or more embodiments of using a current curve to determine whether the valves 154, 194 are operating correctly.

[0145] Thus, for each valve, the control unit 100 can receive current measurements at a predetermined sampling rate for a predetermined duration (block 1104). It should be understood that the sampling rate will need to be high enough to capture the behavior of valves 154, 194. For example, as will be discussed herein Figure 12 as shown by current curve 1200, the sampling frequency can be about 100 to 200 Hz. Additionally, it should be understood that the duration may need to be long enough to capture the critical period where, for successful opening of valves 154, 194, the current curve of the valve will indicate a low point (e.g., at about 22 milliseconds), as previously discussed with respect to Figure 10A and 10B . Blocks 1106 to 1122 can be performed iteratively for each valve being evaluated for a function (e.g., to determine if valves 154, 194 are actually enabled). Additionally or alternatively, blocks 1106 to 1122 can be performed simultaneously for each valve.

[0146] For example, valves 154, 194 can be selected for enablement evaluation (block 1106). Based on the current measurements of the valve (received in block 1104), the control unit 100 can identify the rise time of the valve current (block 1108). The rise time can correspond to the approximate positive slope of the current measurements over time. For successful valve enablement, the rise time can correspond to the positive slope of the current curve after the low point (e.g., after the plunger has completed its movement through the electromagnetic coil and is within the solenoid valve housing). However, it may not yet be known whether valves 154, 194 have been successfully enabled, and the low point of the current curve may not be as distinguishable. The rise time of the current can be identified by evaluating the general slope based on the total current measurements from the time the valve is commanded to be enabled until the time the rise of the current abates. In some aspects, the rise time can be measured by the duration for which the slope of the curve is at least higher than a predetermined value such that the end of the rise time can correspond to the time when the rise of the current measurements abates. For example, based on Figure 12 the sampling frequency shown (e.g., about 100 to 200 Hz), the identified rise time can include 20 current measurements.

[0147] At block 1110, control unit 100 may determine a normalized maximum current value for the valve current curve based on the rise time. In some embodiments, determining the maximum current value may involve comparing the current measurements received for valves 154, 194 selected at 1106 with the current measurements received for other valves 154, 194 of the PD machine 20. It should be understood that the PD system 10 may be configured to appropriately conserve power during valve activation. For example, valves 154, 194 of the PD system 10 may be configured not to operate at full current. Thus, the received current measurements for the valves may each indicate a different maximum current based on the current that each valve 154, 194 may be allotted for activation. Since the maximum current value for each valve may be different, the control unit may determine a maximum current applicable to all or most of the valves 154, 194. The determined maximum current value may be used to normalize (at block 1102) the received current measurements, for example, by dividing each current measurement by the maximum current value.

[0148] At block 1112, a curve of the current measurements may be generated based on the normalization (e.g., using the calculated maximum current value). In some aspects, the generated curve may be based on time samples corresponding to the rise time identified in block 1108, such as by truncating any non - relevant time samples.

[0149] At block 1114, control unit 100 may apply a polynomial model to the curve. In some embodiments, applying the polynomial model may involve initializing the parameters of the polynomial model, e.g., by creating initial estimates and / or randomizing values for missing variables and coefficients of the optimization process.

[0150] Although increasing the sampling rate and / or frequency can facilitate a more effective polynomial model to fit the current curve, it is contemplated that in some embodiments, the polynomial model fitting or estimation may be performed without providing additional sampling. Since the behavior of the current of valves 154, 194 over time can be predicted based on the determination of the maximum current (e.g., from block 1110), one or more data points forward in time may be added to the current curve of the valves. This addition may force the estimated polynomial model fit to better capture the dynamic behavior of the current curve of the valves.

[0151] The polynomial model and its parameters may be optimized in block 1116 (e.g., by recursive or non - recursive estimation processes such as using the least squares mean estimate ("LSME") of the current curve). In at least one embodiment, a polynomial fit of the current curve of the valves may be obtained via the LSME process (e.g., generated in block 1108). Where the current curve includes 20 current measurements (e.g., as Figure 12 and Figure 13In an example embodiment (as shown), a fifth-degree polynomial model can be selected. The higher the polynomial degree, the higher the load on the control unit 100 may be, resulting in increased processing time and a higher burden on the processing capacity. However, the degree may need to be high enough to capture the behavior of the current curve (e.g., the initial peak 1002, the low point 1004, and the subsequent rise 1006), but low enough to be manageable by the control unit 100. The same type of balancing action also applies to the number of samples taken. There should be enough samples to correctly capture the current curve behavior, but not too many samples, which may overload the processor (e.g., the processor 102). In addition, higher-degree polynomials may have undesirable behavior in the fitting process described herein. Therefore, the degree of the polynomial model that can well capture the "low point" of the current curve can be selected (when the valve has been successfully enabled). However, in the case where there is no low point in the current curve of the valve (e.g., the valve opening fails), the higher-order terms can be estimated to be close to 0.

[0152] At block 1116, the polynomial model can be optimized for the current curve through an estimation process (e.g., LMSE). In some embodiments, the polynomial model used in LMSE can be expressed as:

[0153]

[0154] where is the observation vector (i.e., the samples of the current measurements received at block 1104), is the regression matrix, is the parameter vector describing the system (e.g., the polynomial model for calculating the current based on the time stamp), and represents the error of the polynomial fit for the sampled data. Since the sample interval is known and the number of samples is selected (e.g., a sampling interval of 0.001 s and 120 samples), the regression matrix can be calculated as follows:

[0155]

[0156]

[0157]

[0158] In one embodiment, the parameter vector can be represented using the following equation:

[0159] ,

[0160] where is the solution based on error minimization in the original equation discussed above, i.e., (All current samples ). Additionally, it may include a vector having coefficients for calculating current at a given time after enabling. Thus, the polynomial model can be optimized by relying on the coefficients and / or parameters determined by . In some embodiments, by scaling the time used in the regression matrix (e.g., by having multiples of every 0.1 s instead of 0.001 s), the estimation process of the optimized polynomial model can be made more efficient (e.g., and minimize the burden on the processor of the control unit 100) and / or more reliable (e.g., with respect to the risk of accuracy loss).

[0161] At block 1118, the control unit 100 may apply the optimized polynomial model to the trained classification model to determine the enabling state of the valve. The classification model can be trained based on a reference data set of current curves and / or a polynomial model representing such current curves, labeled with the enabling state (e.g., successful enabling or failed enabling). Figure 14 The process 1400 described in Figure 14 provides an example of at least one embodiment for training such a classification model. As will be discussed in

[0162] The output of applying the optimized polynomial model to the trained classification model may include an enabling state of successful enabling (e.g., the class where the polynomial model is fitted based on the current curve of a valve that has been successfully opened) or failed enabling (e.g., the class where the polynomial model is fitted for the current curve of a valve that has failed to open). In some embodiments, depending on the training data labeled for training the classification model, there may be additional options for the output (e.g., no opening, near successful opening, etc.). Thus, the enabling state can be determined, and the control unit 100 can identify at block 1120 whether the valve being evaluated has been successfully enabled (e.g., block 1120 - Yes).

[0163] If it is determined that the valve has been successfully enabled (e.g., based on blocks 1106 to 1120), the control unit 100 may determine whether there are additional valves to be evaluated (block 1124). If there are additional valves, blocks 1106 to 1120 may be repeated for those additional valves to evaluate whether successful enabling has occurred based on their current curves. If it is determined based on the evaluation of the current curves of valves 154, 194 that valves 154, 194 have not been enabled (e.g., block 1120 - no), the control unit 100 may warn the operator of a valve failure. For example, the PD system 10 may generate (e.g., via an indicator display) warnings, alerts, and / or danger symbols, or generate audio or visual cues. After evaluating each valve 154, 194, and / or after any failures have been reported, the control unit 100 may end its evaluation of the valves for their enabling function (block 1126).

[0164] In some embodiments, alternatives to the polynomial model may be used to represent and / or fit the current curves. For example, a logistic model may be used, such as the model represented as: where t is time, is the maximum current, is the current at time t, and is the time constant of the system. This model may be used, for example, to effectively fit the current curves corresponding to valves 154, 194 with failed valve openings (i.e., failed enabling), and thus to detect valves 154, 194 with failed enabling.

[0165] In some embodiments, variants of one or more steps of process 1100 may be used to evaluate the function of solenoid valve deactivation (e.g., closing). For example, after deactivating the valve (block 1102), current measurements may be received at a predetermined sampling rate for a predetermined duration (block 1104). For one or more valves to be evaluated, curves of current measurements may be generated using the process described above (blocks 1104 to 1112). A polynomial model may be applied and optimized to the current curve (blocks 1114 and 1116). When a given solenoid valve is commanded to deactivate, the optimized polynomial model estimating the current curve of the given solenoid valve may then be applied to a trained classification model (e.g., a support vector machine), which may detect whether there is an actual or failed deactivation of the solenoid valve, e.g., closing (block 1118). The trained classification model used to detect deactivation may be different from the trained classification model used to detect enabling, as the former may rely on reference training data for two sets of current curves associated respectively with (i) successful valve deactivation and (ii) failed valve deactivation.

[0166] Figure 12is a sampled and normalized current curve 100 with solenoid valves 154, 194 successfully enabled, according to an exemplary embodiment of the present disclosure. For example, the current curve 1200 may be generated by the control unit 100 at block 1112 of process 1100 (e.g., after normalizing each current measurement based on the maximum current). The stepped nature of the current curve 1200 (e.g., as opposed to the current curves shown in Figure 10A and 10B ) may be produced by a lower sampling frequency, which may facilitate more efficient processing to evaluate valve enabling functionality. The increased efficiency due to the lower sampling rate may allow for faster and more effective warning of valve failures in the PD system 10, thereby improving patient care. As previously discussed with respect to Figure 10A and Figure 10B , the current curve 1200 may correspond to successfully enabled valves 154, 194 due to a characteristic “low point” of the current (e.g., at approximately 22 milliseconds). However, in a current curve with a smaller sampling rate (e.g., current curve 1200), it may be difficult to identify the “low point”. Accordingly, the PD system 10 (via its control unit 100) may rely on process 1100 to determine that the current curve 1200 corresponds to a valve with a successful enablement.

[0167] In contrast, Figure 13 is a sampled and normalized current curve 1300 with solenoid valves 154, 194 enabled unsuccessfully, according to an exemplary embodiment of the present disclosure. Similar to the current curve 1200 in Figure 12 , the current curve 1300 may be generated by the control unit 100 at block 1112 of process 1100 (e.g., after normalizing each current measurement based on the maximum current). The stepped nature of the current curve 1300 (e.g., as opposed to the current curves shown in Figure 10A and 10B ) may be produced by a lower sampling frequency, which makes it more difficult to discern any characteristic “low point” or its absence to evaluate whether the current curve 1300 indicates a successful or failed valve opening. However, as previously mentioned, process 1100 may be used to determine that the current curve 1300 corresponds to a valve with an unsuccessful enablement.

[0168] Figure 14FIG. 1400 is a flowchart of an example process 1400 for training a classification model (e.g., SVM) for evaluating solenoid valve enabling functions according to an exemplary embodiment of the present disclosure. As described above, process 1400 illustrates an example embodiment for training a classification model (e.g., to feed an optimized polynomial model) used in block 1118 of process 1100. Process 1400 may be executed by a computing system (e.g., the control unit 100 of the PD system 10) having one or more processors (e.g., processor 102). For example, processor 102 may execute process 1400 based on computer-executable instructions stored in memory 104. Although in some embodiments, process 1400 may occur in a remote computing system (e.g., a remote server or a big data analysis laboratory) different from the control unit 100 of the PD system 10, for ease of explanation, process 1400 will be described as being executed by the control unit 100 of the PD system 10.

[0169] Process 1400 may begin with the control unit 100 receiving a reference data set (block 1402) corresponding to a plurality of current curves of valves 154, 194 that have been successfully enabled. This reference data set may be referred to as the first reference data set to distinguish it from an additional reference data set (referred to as the second reference data set) received at block 1406 corresponding to a plurality of additional current curves of valves that have failed to be enabled.

[0170] The first reference data set may be labeled as having a successful enabling result (block 1404). For example, the first reference data set may be vectorized (e.g., by quantifying its current measurements) and associated with a binary indicator (e.g., "true" or "1") indicating successful enabling.

[0171] At block 1406, the control unit 100 may receive a second reference data set of a plurality of reference current curves corresponding to valves 154, 194 that have failed to be enabled (e.g., valves that have failed to open during the duration corresponding to the current curve). The second reference data set may be labeled as having a failed enabling result (block 1408). For example, the second reference data set may be vectorized (e.g., by quantifying its current measurements) and associated with a binary indicator (e.g., "false" or "0") indicating failed enabling.

[0172] At block 1410, the control unit 100 may define parameters for a classification model (e.g., SVM) for supervised training to determine a decision boundary between data corresponding to successful enabling and data corresponding to failed enabling. For example, each data set, whether corresponding to the first reference data set or the second reference data set, may be based on or may be fitted to a polynomial model of a predetermined degree (e.g., five times) (e.g., using the LSME method explained in block 1116 of process 1100). For an nth-degree polynomial model, the coefficients of each degree up to that nth degree may be used as parameters of the classification model (e.g., SVM) to plot and / or locate individual data points (i.e., observations).

[0173] At blocks 1412 and 1414, different decision boundaries may be tested (block 1412) to see how effectively they separate data belonging to the first reference data set from the second reference data set until convergence is reached (block 1414). In some embodiments, convergence may indicate that the tested decision boundary produces the maximum margin between data points belonging to the first reference data set and data points belonging to the second reference data set. Additionally, the decision boundary may indicate on which side (e.g., the side corresponding to the first reference data set for successful enabling or the side corresponding to the second reference data set for failed enabling) a given polynomial model may fall based on the coefficients of each parameter of the polynomial model.

[0174] At block 1416, the trained classification model, e.g., a trained support vector machine with parameters for the decision boundary, may be stored (e.g., in the memory 104 of the control unit 100). Thus, the trained support vector machine may be used to apply the optimized polynomial model from process 1100 to determine whether the current curve belongs to the side of successful enabling (e.g., the same side as the first reference data set) or the side of failed enabling (e.g., the same side as the second reference data set).

[0175] A trained classification model (such as a support vector machine) can include a supervised learning model that analyzes training data (e.g., a plurality of current curves used as references (referred to herein as reference current curves), and the knowledge of whether each reference current curve corresponds to a successful or failed activation), to automatically learn (e.g., via an iterative error minimization process) the relationship between input data (e.g., various parameters of any given current curve) and two or more discrete outcomes (e.g., whether the current curve corresponds to a successful or failed activation). The learned relationship can then be applied to test data with an unknown outcome (e.g., the current curve of a valve with an unknown valve activation state) to determine the outcome (e.g., whether the valve has actually been successfully activated). An SVM can be an example of a classification model, where the learned relationship is a decision boundary (e.g., separating the current curves of valves with successful valve activations from the current curves of valves with failed valve activations).

[0176] In some embodiments, variations of one or more steps of process 1400 can be used to train a classification model for evaluating the functionality of solenoid valve deactivation (e.g., whether the valve has actually closed). For example, a first reference data set can include a plurality of reference current curves indicating successful deactivation or valve closure (block 1402), while a second reference data set can include a plurality of reference current curves indicating failed deactivation or valve closure (block 1406). The first and second reference data sets can be labeled as successful deactivation (block 1404) and failed deactivation (block 1408), respectively. The labeled data sets can be used for the training process (blocks 1410 to 1414), and the resulting trained support vector machine can be stored for (block 1416) identifying whether a given valve has been successfully deactivated.

[0177] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Accordingly, these changes and modifications are intended to be covered by the appended claims. For example, while MOSFETs and NPN transistors are described as the transistors used to assist in noise reduction during solenoid valve enabling and disabling, other transistors can similarly be used to slow down the plunger in a solenoid valve to similarly reduce noise. As another example, while a support vector machine is used to classify current curves of valves with successfully enabled valves and current curves of valves with failed enables, other machine learning models can be used for this classification. As another example and as discussed herein, the systems and methods of the present disclosure can be used to evaluate valve actuation (e.g., whether a valve is actually open) and valve deactivation (e.g., whether a valve is actually closed). For example, an optimized polynomial model of the current curve of a solenoid valve when the solenoid valve is commanded to deactivate can be applied to a trained classification model to determine whether the solenoid valve has actually closed. In yet another example, any solenoid valve discussed herein can be, but is not required to be, an electromagnetic pinch valve. In yet another example, while different valve embodiments are discussed primarily in connection with peritoneal dialysis (“PD”), the valve embodiments can be used with other medical fluid systems and associated machines, such as machines for hemodialysis (“HD”), hemofiltration (“HF”), hemodiafiltration (“HDF”), and continuous renal replacement therapy (“CRRT”).

Claims

1. A medical fluid system, comprising: A control unit; A plurality of NPN transistors configured to control a plurality of valves in response to control signals received from the control unit; A plurality of valves, Wherein each valve includes a housing, a coil, and a plunger, and Wherein each valve is configured to allow the flow of medical fluid through a tube by applying a voltage to a corresponding coil via an associated NPN transistor to move a corresponding plunger within a corresponding housing; and Wherein the control unit includes at least one processor and at least one memory, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the at least one processor to: Send a control signal to one of the NPN transistors, the control signal being configured to cause a ramped increase in the input current to the NPN transistor, Wherein the ramped increase in the input current to the NPN transistor causes the corresponding valve to ramp up the voltage applied to the corresponding coil, and Wherein the ramped increase in the voltage applied to the corresponding coil causes the corresponding plunger to move in a manner that reduces the sound generated by the corresponding plunger compared to an operation without the NPN transistor.

2. The medical fluid system according to claim 1, wherein, The control signal is configured to place the NPN transistor in the non - saturation region.

3. The medical fluid system according to claim 1, wherein, Each valve is configured to close the flow of medical fluid through the tube by not applying the voltage caused by the corresponding NPN transistor to the corresponding coil such that the corresponding plunger moves in the opposite direction to block the corresponding tube.

4. The medical fluid system according to claim 3, wherein, The instructions, when executed by the at least one processor, further cause the at least one processor to: Turn off the low control signal, wherein the turn - off causes a ramped decrease in the input current to the NPN transistor, Wherein the ramped decrease in the input current to the NPN transistor causes the corresponding valve to ramp down the voltage applied to the corresponding coil, and Wherein the ramped decrease in the voltage applied to the corresponding coil causes the corresponding plunger to move in the opposite direction and in a manner that reduces the sound generated by the corresponding plunger compared to an operation without the NPN transistor.

5. A medical fluid system, comprising: A control unit; A plurality of metal - oxide - semiconductor field - effect transistors ("MOSFETs") configured to control a plurality of valves in response to control signals received from the control unit; A plurality of valves, Wherein each valve includes a housing, a coil, and a plunger, and Wherein each valve is configured to allow the flow of medical fluid through a tube by applying a voltage to a corresponding coil via an associated MOSFET to move a corresponding plunger within a corresponding housing; The control unit includes at least one processor and at least one memory, wherein the at least one memory stores instructions that, when executed by the at least one processor, cause the at least one processor to: Send a high - digital control signal to one of the MOSFETs, Wherein, in response to the high - digital control signal, the MOSFET causes the corresponding valve to ramp up the voltage applied to the corresponding coil until the voltage reaches a predetermined input voltage Vin, and Wherein, a ramp-up of the voltage applied to the corresponding coil causes the corresponding plunger to move in a manner that reduces the sound generated by the corresponding plunger as compared to the operation without the MOSFET.

6. The medical fluid system according to claim 5, wherein, Each valve is configured to close the flow of medical fluid through the tube by not applying a voltage to the corresponding coil via the corresponding MOSFET, causing the corresponding plunger to move in the opposite direction to block the corresponding tube.

7. The medical fluid system according to claim 6, wherein, The instructions, when executed by the at least one processor, further cause the at least one processor to: Send a low digital control signal to one of the plurality of MOSFETs, wherein the MOSFET, in response to the low digital control signal, causes the corresponding valve to ramp down the voltage applied to the corresponding coil until the voltage reaches 0 volts, and wherein the ramp-down of the voltage applied to the corresponding coil causes the corresponding plunger to move in the opposite direction and in a manner that reduces the sound generated by the corresponding plunger as compared to the operation without the MOSFET.

8. The medical fluid system according to claim 7, further comprising: At least one resistor, the at least one resistor being arranged in series between the control unit and the MOSFET; wherein the duration of the ramp-up of the voltage applied to the corresponding coil is based on at least one resistance value of the corresponding at least one resistor; And wherein the duration of the ramp-down of the voltage applied to the corresponding coil is based on the at least one resistance value of the corresponding at least one resistor.

9. The medical fluid system according to claim 8, further comprising: At least one capacitor, the at least one capacitor being arranged in series between the control unit and the MOSFET; wherein the duration of the ramp-up of the voltage applied to the corresponding coil is further based on the capacitance value of the corresponding at least one capacitor; And wherein the duration of the ramp-down of the voltage applied to the corresponding coil is further based on the capacitance value of the corresponding at least one capacitor.

10. The medical fluid system according to claim 5, further comprising an initial ramp offset circuit, the initial ramp offset circuit including a feedback resistor.

11. The medical fluid system according to claim 10, wherein, The instructions, when executed, further cause the processor to: Apply an offset voltage via the initial ramp offset circuit, the offset voltage being set lower than the voltage applied to the corresponding coil when ramping up the input current to the MOSFET.

12. A medical fluid system, comprising: A control unit; A plurality of input / output ("I / O") nodes, the plurality of input / output nodes being configured to control a plurality of valves via pulse width modulation ("PWM") signals in response to control signals received from the control unit; A plurality of valves, wherein each valve includes a housing, a coil, and a plunger, and wherein each valve is configured to allow the flow of medical fluid through a tube by applying a voltage to the corresponding coil via an associated I / O node to move the corresponding plunger within the corresponding housing; and The control unit includes at least one processor and at least one memory, wherein the at least one memory stores instructions, the instructions, when executed by the at least one processor, cause the at least one processor to: Send a control signal to one of the plurality of I / O nodes, the control signal causing the one I / O node to apply a PWM signal to a corresponding coil and ramp up the PWM signal, and wherein the ramp up of the PWM signal causes the corresponding plunger to move in a manner that reduces the sound generated by the corresponding plunger compared to operation without the PWM signal.

13. The medical fluid system according to claim 12, wherein, The ramp up of the PWM signal includes ramping up the duty cycle of the pulsed voltage application to the corresponding coil from 0% to 100% over a period of 50 milliseconds.

14. The medical fluid system according to claim 12, wherein, The instructions, when executed, further cause the processor to: After the plunger reaches the end position, send a second control signal to the I / O node, the second control signal causing the I / O node to ramp down the PWM signal to the corresponding coil to a duty cycle of at least 25%.

15. The medical fluid system according to claim 14, wherein, The second control signal causes the I / O node to ramp down the PWM signal to the corresponding coil to a duty cycle of at least 50%.

16. The medical fluid system according to claim 14, wherein, Each valve is configured to close the flow of medical fluid through the tube by moving a corresponding plunger in an opposite direction to block the corresponding tube by not applying a voltage to the corresponding coil via a corresponding I / O node.

17. The medical fluid system according to claim 16, wherein, The instructions, when executed by the at least one processor, further cause the at least one processor to: Send a third control signal to the I / O node, the third control signal causing the I / O node to ramp down the PWM signal to the corresponding coil to a duty cycle of 0%, wherein the ramp down of the PWM signal to the corresponding coil causes the corresponding plunger to move in an opposite direction and in a manner that reduces the sound generated by the corresponding plunger compared to operation without the PWM signal.

18. The medical fluid system according to claim 17, wherein, The ramp down of the PWM signal to a duty cycle of 0% occurs between 25 milliseconds and 75 milliseconds.

19. The medical fluid system according to claim 17, further comprising: At least one resistor, the at least one resistor being arranged in series between the control unit and the I / O node; wherein the duration of the ramp up of the PWM signal is based on the resistance value of the corresponding at least one resistor; and wherein the duration of the ramp down of the PWM signal is based on the resistance value of the corresponding at least one resistor.

20. The medical fluid system according to claim 17, further comprising: At least one capacitor, the at least one capacitor being arranged in series between the control unit and the I / O node; wherein the duration of the ramp up of the PWM signal is further based on the capacitance value of the corresponding at least one capacitor; and wherein the duration of the ramp down of the PWM signal is further based on the capacitance value of the corresponding at least one capacitor.

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