Dialysis system with reduced valve noise

Abstract

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

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to medical fluid therapy, and more particularly to dialysate therapy using valves for medical fluid control. [Background technology]

[0002] A person's renal system can fail due to a variety of causes. Renal failure produces several physiological disturbances. It is no longer possible to balance water and minerals or excrete the daily metabolic load. Toxic end products of metabolism, such as urea, creatinine, uric acid, and others, can accumulate in the patient's blood and tissues.

[0003] Declining kidney function, particularly kidney failure, is treated with dialysis, which removes waste products, toxins, and excess water from the body that normally would be removed by normally functioning kidneys. Dialysis treatment for kidney function replacement is crucial for many people because the treatment is lifesaving.

[0004] One type of kidney failure therapy is hemodialysis ("HD"), which generally 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 dialysate to cause diffusion.

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

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

[0007] Most HD, HF, and HDF treatments are performed in centers. Today, there is a trend toward home hemodialysis ("HHD"), in part because HHD can be performed daily, offering therapeutic benefits over in-center hemodialysis treatments, which are typically performed twice or three times a week. Studies have shown that more frequent treatments remove more toxins and waste products and result in less interdialytic fluid overload than patients receiving less frequent but potentially longer treatments. Patients receiving more frequent treatments do not experience as much downcycling (fluid and toxin fluctuations) as in-center patients who accumulate two or three days' worth of toxins before treatment. In certain regions, the nearest dialysis facility may be many miles from a patient's home, causing door-to-door treatment times to consume a significant portion of a patient's day. Treatments at facilities closer to the patient's home can also consume a significant portion of a patient's day. HHD can be performed at night or during the day when the patient is relaxing, working, or otherwise productive.

[0008] Another type of renal failure therapy is peritoneal dialysis ("PD"), which infuses a dialysis solution, also called dialysate, into a patient's peritoneal cavity through a catheter. The dialysate contacts the peritoneal membrane within the patient's peritoneal cavity. Waste, toxins, and excess water move from the patient's bloodstream through capillaries in the peritoneal membrane into the dialysate by diffusion and osmosis; i.e., an osmotic gradient is created across the membrane. Osmotic agents in the PD dialysate create the osmotic gradient. Spent or spent dialysate is pumped out of the patient, removing the waste, toxins, and excess water from the patient. This cycle may be repeated, for example, multiple 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. In this, the patient manually connects an implanted catheter to a drain, allowing used or spent dialysate to drain from the peritoneal cavity. The patient then switches the fluid connection, whereby the patient catheter communicates with a bag of fresh dialysate and infuses fresh dialysate into the patient through the catheter. The patient disconnects the catheter from the bag of fresh dialysate, allowing the dialysate to dwell in the peritoneal cavity, where waste, toxins, and excess water are transported. After the dwell period, the patient repeats the manual dialysis procedure, for example, four times a day. Manual peritoneal dialysis requires significant patient time and effort and leaves significant room for improvement.

[0010] Automated peritoneal dialysis ("APD") is similar to CAPD in that dialysis treatment involves drain, fill, and dwell cycles. APD machines, however, perform these cycles automatically, typically while the patient sleeps. APD machines relieve patients of having to manually perform treatment cycles and transport supplies during the day. APD machines are fluidly connected to an implanted catheter, a source or bag of fresh dialysate, and a fluid drain. APD machines pump fresh dialysate from the dialysate source through the catheter and into the patient's peritoneal cavity. APD machines also allow the dialysate to dwell within the cavity, allowing for the transfer of waste, toxins, and excess water. The source may contain multiple liters of dialysate, including several solution bags.

[0011] APD machines pump used or spent dialysate from the patient's peritoneal cavity and drain it through a catheter. Similar to the manual process, several drain, fill, and dwell cycles occur during dialysis. A "final fill" may occur at the end of an APD treatment. The final fill fluid may remain in the patient's peritoneal cavity until the start of the next treatment, or it may be manually emptied at some point during the day.

[0012] Each of the dialysis modalities identified above, except for CAPD (which typically does not involve a machine), uses automated valves to control whether dialysate, blood, or other fluids can or cannot flow. Valves also control the direction of fluid flow, such as where the fluid comes from or where it flows to. Different types of valves are used in dialysis systems. One type of valve is typically used with a disposable cassette having a rigid plastic part 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 part. The disposable cassette is typically loaded into a dialysis machine or cycler, which can close designated portions of one or more plastic sheets against the valve seat to block fluid flow and force or allow the plastic to move away from the valve seat to allow fluid flow.

[0013] Another type of automated valve is the pinch valve, which instead pinches and closes the tubing carrying dialysate, blood, or other fluids to block fluid flow. Here, a hard plastic disposable cassette is not required, saving costs. Generally, there are two types of pinch valves: solenoid pinch valves and motorized pinch valves. Another type of automated valve is the solenoid plunger valve. A solenoid plunger valve uses a plunger to move a lever that presses against a seat to stop flow (or moves a lever to press a seat to allow flow). One problem with solenoid pinch valves and solenoid plunger valves (collectively referred to herein as "solenoid valves") is noise. For example, solenoid plunger valves generally involve energizing a coil that moves a plunger within a housing. The plunger can be moved while the coil is energized to allow the tubing to open for fluid flow. When energy is removed from the coil, the compressed spring is allowed to push the plunger in the opposite direction, closing the tube against a stop or wall located at the opposite end of the tube. A plunger moving in either direction encounters a travel stop, which involves the plunger contacting a fixed surface, either directly or with the tube in between. The travel stop contact generates noise. Particularly in the case of APD therapy, which typically occurs at night while the patient is sleeping, noise from the solenoid valve can be problematic by waking the patient.

[0014] Another problem with solenoid valves is knowing that the valve is open when energized, i.e., that energizing the coil actually moved the plunger (e.g., in a solenoid plunger valve) or actually removed the pinch in the tubing so that it no longer obstructs the tubing or fluid flow (e.g., in a solenoid pinch valve). Assuming the valve is open when it is not can create an undesirable situation.

[0015] With respect to each of the above problems, an improved method of operating a solenoid valve is needed. Summary of the Invention [Means for solving the problem]

[0016] The present disclosure describes a method of operating a solenoid valve for use in a medical fluid system, such as an automated peritoneal dialysis ("PD") system, that improves the usability of the valve. While the system is primarily described in the context of PD, the improved solenoid valve operation of the present disclosure applies to devices used in 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 also applies to any medical fluid system in which therapy fluid flow, or patient fluid flow, is controlled by one or more valves.

[0017] In the PD example, the system includes a PD device or cycler. The PD device is described herein primarily as a durable system that attempts to limit disposable waste as much as possible, for example, by using an electromechanical piston pump to pump medical fluid or PD fluid through the body of the pump. The PD fluid pump can also be an electromechanically driven gear, peristaltic, or centrifugal pump. In further alternative embodiments, a pneumatically driven PD fluid pump can be used. Any of the above pumping scenarios can be used in combination with the electromechanically actuated solenoid valves of the present disclosure. In one embodiment, the PD device or cycler can deliver unused, heated PD fluid to the patient at, for example, 14 kPa (2.0 psig) or higher. The PD device can remove used PD fluid or effluent from the patient at negative pressures, for example, -9 kPa (-1.3 psig) or even greater. The unused PD fluid delivered to the patient can be initially heated to body fluid temperature, for example, 37°C.

[0018] The PD device or cycler also includes multiple valves, any one, more, or all of which may be solenoid valves. The solenoid valves described herein may be of any type. For example, one type of solenoid valve uses an internal fluid path that opens or closes depending on whether a coil is energized. This type of solenoid valve is well suited to durable or reusable versions of the PD device or cycler. Another type of solenoid valve operates by opening or closing flexible tubing depending on whether a coil is energized. This type of solenoid valve is well suited to versions of the PD device or cycler that operate with disposable sets, but may also be used in durable versions of the PD device or cycler that have internal flexible tubing for operation with the solenoid valve.

[0019] (Noise reduction) The PD device or cycler of the system operates in conjunction with a solenoid valve under the control of a control unit. The control unit in various embodiments implements measures to control the movement of the solenoid valve to minimize the amount of noise generated during impacts during valve activation and deactivation. The measures generally involve slowing the movement of the valve plunger within the valve coil. Modifications that slow the valve movement result in less impact with the valve housing, producing a lower level of impact noise.

[0020] One structure and methodology for slowing the actuation of a solenoid valve is to provide a ramping transistor to the electronics controlling the valve. A transistor can be used to linearly control the voltage applied to the coil of the solenoid valve. There are various variations of transistors that can be used to slow the actuation of a solenoid valve, including NPN transistors and metal-oxide semiconductor field-effect transistors (MOSFETs). The two different types of transistors have different capabilities and positive aspects.

[0021] The disclosed system provides a control unit having one or more processors and one or more memories for controlling the disclosed solenoid valve. For example, the control unit may provide electrical control using an ON / OFF signal to control an NPN transistor. In one embodiment, the control unit maintains the control signal at a low level, for example, in the transistor's non-saturation region, and the voltage applied to the solenoid coil is increased over time by increasing the input current to the transistor. The electrical result here is similar to that of a low-pass filter, which does not require a large capacitance or resistance in series with the solenoid. One disadvantage of using an NPN transistor to slow the power applied to the solenoid valve coil is that the NPN transistor has a relatively high resistance, which generates heat.

[0022] Alternatively, the control unit of the present disclosure may operate with one or more MOSFETs, such as P-channel MOSFETs. Here, the control unit provides a digital output control signal to the MOSFETs. When a control signal from the control unit to a first MOSFET via ramping electronics goes high, the output signal from the second MOSFET increases over time until it reaches the solenoid coil voltage Vin. When the control signal from the control unit to the first MOSFET goes low (e.g., by ramping the control signal via associated electronics between the control unit and the first MOSFET), the output voltage from the second MOSFET slowly drops to 0 V. The voltage ramp-up and ramp-down times can be adjusted by changing the value of the associated capacitor. Ramping the solenoid voltage using MOSFETs adds undesirable turn-on and turn-off delays to the control of the solenoid valve. To reduce 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 minimum voltage that triggers valve plunger movement. In one embodiment, the ramp offset voltage is set by adjusting a feedback resistor in the circuit. One advantage of using a MOSFET to slowly ramp the valve on and off is that less electromagnetic interference ("EMI") is radiated and / or conducted because there are regenerating and / or rapidly changing voltage flanks.

[0023] A further alternative structure and methodology for slowing solenoid valve actuation is to use pulse-width modulation ("PWM"). PWM has the advantage over simply lowering the supply voltage in that it virtually guarantees that the full voltage is eventually applied to the solenoid coil and moves the solenoid valve's plunger. In one embodiment, the control unit applies PWM by pulsing the input voltage on and off, increasing the voltage over time, until the solenoid valve's plunger moves to the open position (two-way valve) or flow path switching position (three-way valve). Such pulsing and ramping allows for slower plunger movement, thus allowing for less impact with the valve housing during actuation and deactivation and reducing noise. PWM can also be used during normal operation (e.g., steady-state operation requiring less voltage), which allows for lower overall power demands during treatment and keeps the PD device or cycler cool. For example, during steady-state operation, the voltage required to hold the plunger in an open position may be less (e.g., 12-16 VDC) compared to the voltage typically required for valve actuation or deactivation (e.g., approximately 24 VDC). Thus, PWM applied during steady-state operation results in lower power consumption.

[0024] In one example of PWM, the control unit's master processor provides a command to the control unit's input / output driver to energize one of the PD device's solenoid valves. The input / output driver cycles the PWM signal to the solenoid valve's coil on and off from zero to 100%, for example, every 50 milliseconds ("ms"). After the solenoid valve's plunger reaches its end-of-travel position, the input / output driver reduces the voltage level to, for example, 50% of the final operating power level (e.g., to keep the valve energized in the open position) to reduce power consumption and heat generation. When it is time to close a two-way valve or switch the flow path of a three-way valve, the I / O driver reduces the PWM voltage level from 50% of the plunger hold level to zero, for example, over 50 ms.

[0025] The ramp-up or ramp-down duration of the voltage applied to the solenoid coil of the valve may be adjusted for any of the noise reduction methods described herein. For example, a resistor and / or capacitor may be placed between the control unit and one of the NPN transistors, MOSFETs, or I / O nodes associated with the valve. The resistance and / or capacitance values ​​may be selected to set the ramp-up and / or ramp-down durations accordingly.

[0026] (Evaluation of the functionality of solenoid valve actuation) As described herein, solenoid valves typically open by energizing a coil that moves a plunger within the solenoid valve housing (e.g., in the case of a solenoid plunger valve) and / or by releasing a pinched tube (e.g., in the case of a solenoid pinch valve). However, it is desirable and necessary to assess whether a solenoid valve in a medical fluid device or cycler (e.g., a PD, HD, HF, HDF, and / or CRRT device or cycler) is actually open when energized and actually closed when de-energized or deactivated. Otherwise, a situation may arise in which dialysate is not flowing when it should be, or is flowing when it should not. Various embodiments of the presently disclosed systems and methods are provided for assessing valve activation (e.g., whether the valve is properly open) or valve deactivation (e.g., whether the valve is actually closed). In at least one embodiment, current measurements may be received from the solenoid valve at a predetermined sampling rate over a predetermined duration to generate a current profile for the solenoid valve. For example, a fifth-order polynomial model may be fitted to the current profile and optimized. The optimized polynomial model may be applied to a trained classification model (e.g., a trained support vector machine (“SVM”)) to determine whether the current profile indicates that the corresponding solenoid valve is actually open or closed.

[0027] A trained classification model, such as a trained SVM, may include a supervised learning model that analyzes training data (e.g., multiple current profiles used as references (referred to herein as reference current profiles) and knowledge of whether each reference current profile corresponds to successful or unsuccessful actuation) to automatically learn (e.g., via an iterative error minimization process) relationships between input data (e.g., various parameters of any given current profile) and two or more discrete outcomes (e.g., whether the current profile corresponds to successful or unsuccessful actuation). The learned relationships may then be applied to test data having unknown outcomes (e.g., current profiles of valves whose valve actuation state is unknown) to determine an outcome (e.g., whether the valve actually actuated successfully). An SVM may be an example of a classification model in which the learned relationships are decision boundaries (e.g., to separate current profiles of valves with successful valve actuation from current profiles of valves with unsuccessful valve actuation).

[0028] In a first aspect of the present disclosure, which in light of the disclosure set forth herein does not limit the disclosure in any way, but which may 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; and a plurality of valves, each valve including a housing, a coil, and a plunger, each valve configured to apply a voltage to a corresponding coil via an associated NPN transistor to move a corresponding plunger within a corresponding housing, thereby allowing flow of medical fluid through a tube; comprises at least one processor and at least one memory, the at least one memory storing instructions that, when executed by the at least one processor, cause the at least one processor to transmit a control signal to one of the NPN transistors configured to cause a ramp-up of an input current to the NPN transistor, the ramp-up of the input current to the NPN transistor causing a corresponding valve to ramp-up a voltage applied to a corresponding coil, the ramp-up of the voltage applied to the corresponding coil causing the corresponding plunger to move in a manner such that a sound produced by the corresponding plunger is reduced compared to operation without the NPN transistor.

[0029] In a second aspect of the present disclosure that may be combined with any other aspect or portion thereof, the control signal is configured to place the NPN transistor in a non-saturation region.

[0030] In a third aspect of the present disclosure, which may be combined with any other aspect or portion thereof, each valve is configured to close the flow of medical fluid through the tube by not applying a voltage to a corresponding coil generated by a corresponding NPN transistor, such that a corresponding plunger moves in the opposite direction and occludes a corresponding tube.

[0031] In a fourth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the instructions, when executed by the at least one processor, cause the at least one processor to further turn off a low control signal, the turning off causing an input current to an NPN transistor to ramp down, the ramping down of the input current to the NPN transistor causing a voltage applied to a coil corresponding to the corresponding valve to ramp down, the ramping down of the voltage applied to the corresponding coil causing the corresponding plunger to move in an opposite direction and in a manner such that a sound generated by the corresponding plunger is reduced compared to operation without the NPN transistor.

[0032] In a fifth aspect of the present disclosure that may be combined with any other aspect or portion 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; and a plurality of valves, each valve including a housing, a coil, and a plunger, each valve configured to enable 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 the corresponding housing; the control unit includes at least one processor and at least one memory, the at least one memory storing instructions that, when executed by the at least one processor, cause the at least one processor to transmit a high digital control signal to one of the MOSFETs, the MOSFET, in response to the high digital control signal, causes the corresponding valve to ramp up a voltage applied to the corresponding coil until the voltage reaches a predetermined input voltage Vin, the ramping up of the voltage applied to the corresponding coil moving the corresponding plunger in a manner that reduces sound generated by the corresponding plunger compared to operation without the MOSFET.

[0033] In a sixth aspect of the present disclosure that may be combined with any other aspect or portion thereof, each valve is configured to close the flow of medical fluid through the tube by not applying a voltage to a corresponding coil via a corresponding MOSFET such that a corresponding plunger moves in the opposite direction and occludes a corresponding tube.

[0034] In a seventh aspect of the present disclosure, which may 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 transmit low digital control signals to MOSFETs of the plurality of MOSFETs, which, in response to the low digital control signals, cause corresponding valves to ramp down a voltage applied to a corresponding coil until the voltage reaches 0 volts, wherein the ramping down of the voltage applied to the corresponding coil causes the corresponding plunger to move in an opposite direction and in a manner such that sound produced by the corresponding plunger is reduced compared to operation without the MOSFET.

[0035] In an eighth aspect of the present disclosure that may be combined with any other aspect or portion thereof, the medical fluid system further includes at least one resistor arranged in series between the control unit and the MOSFET, wherein a 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 a duration of the ramp-down of the voltage applied to the corresponding coil is based on at least one resistance value of the corresponding at least one resistor.

[0036] In a ninth aspect of the present disclosure that may be combined with any other aspect or portion thereof, the medical fluid system further includes at least one capacitor arranged in series between the control unit and the MOSFET, wherein a duration of the ramp-up of the voltage applied to the corresponding coil is further based on a capacitance value of the corresponding at least one capacitor, and a duration of the ramp-down of the voltage applied to the corresponding coil is further based on a capacitance value of the corresponding at least one capacitor.

[0037] In a tenth aspect of the present disclosure that may be combined with any other aspect or portion thereof, the medical fluid system further includes an initial ramp offset circuit including a feedback resistor.

[0038] In an eleventh aspect of the present disclosure that may be combined with any other aspect or portion thereof, the instructions, when executed, cause the processor to further apply, via an initial ramp offset circuit, an offset voltage that is set lower than the voltage applied to the corresponding coil when ramping up the input current to the MOSFET.

[0039] In a twelfth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a medical fluid system comprises: 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; and a plurality of valves, each valve comprising a housing, a coil, and a plunger, each valve configured to enable flow of medical fluid through a tube by applying a voltage to a corresponding coil via an associated I / O node to move a corresponding plunger within a corresponding housing; the control unit comprising at least one processor and at least one memory, the at least one memory storing instructions, when executed by the at least one processor, causing at least one to transmit a control signal to an I / O node of the plurality of I / O nodes, causing the I / O node to apply a PWM signal to ramp up the corresponding coil, the ramping up of the PWM signal moving the corresponding plunger in a manner such that sound generated by the corresponding plunger is reduced compared to operation without the PWM signal.

[0040] In a thirteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, ramping up the PWM signal includes ramping up the duty cycle of the pulse application of voltage to the corresponding coil from 0% to 100% over a period of 50 ms.

[0041] In a fourteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the instructions, when executed, cause the processor to further transmit a second control signal to the I / O node after the plunger reaches an end position, 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%.

[0042] In a fifteenth aspect of the present disclosure that may be combined with any other aspect or portion 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%.

[0043] In a sixteenth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, 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 I / O node, such that the corresponding plunger moves in the opposite direction and occludes the corresponding tube.

[0044] In a seventeenth aspect of the present disclosure, which may 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 transmit a third control signal to the I / O node that causes the I / O node to ramp down the PWM signal to the corresponding coil to a 0% duty cycle, the ramping down of the PWM signal to the corresponding coil causing the corresponding plunger to move in the opposite direction and in a manner such that the sound generated by the corresponding plunger is reduced compared to operation without the PWM signal.

[0045] In an eighteenth aspect of the present disclosure that may be combined with any other aspect or portion thereof, reducing the PWM signal to the corresponding coil to a 0% duty cycle occurs between 25 and 75 ms.

[0046] In a nineteenth aspect of the present disclosure, which may be combined with any other aspect or portion 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 ramp-up duration of the PWM signal is based on the resistance value of the corresponding at least one resistor, and the ramp-down duration of the PWM signal is based on the resistance value of the corresponding at least one resistor.

[0047] In a twentieth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the medical fluid system further includes at least one capacitor arranged in series between the control unit and the I / O node, and the ramp-up duration of the PWM signal is further based on the capacitance value of the corresponding at least one capacitor, and the ramp-down duration of the PWM signal is further based on the capacitance value of the corresponding at least one capacitor.

[0048] In a twenty-first aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a medical fluid system includes a plurality of valves, each valve including a housing, a coil, and a plunger, each valve configured to allow flow of medical fluid through a tube by energizing a corresponding coil and moving a corresponding plunger within the corresponding housing, and each valve configured to close flow of medical fluid through the tube by de-energizing the corresponding coil and moving the corresponding plunger in the opposite direction within the corresponding housing to occlude the corresponding tube, at least one processor, and at least one memory having instructions stored therein. and at least one memory, wherein the instructions, when executed by the at least one processor, cause the at least one processor to receive measured current values ​​at a predetermined sampling rate for a predetermined duration during operation of at least one of the plurality of valves, generate a current profile for the at least one valve based on the respective measured current values ​​for the at least one valve, generate a polynomial model for the at least one valve based on the respective current profile for the at least one valve, and apply the respective polynomial model to the trained classification model for the at least one valve to assess an operating state for the valve.

[0049] In a twenty-second aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the operating status indicates one of successful operation or failed operation, and the instructions, when executed, further cause the system to generate an alert indicating a malfunction of a valve associated with the failed operation based on the operating status indicating the failed operation.

[0050] In a twenty-third first aspect of the present disclosure, which may be combined with any other aspect or portion thereof, instructions, when executed, cause a system to generate a polynomial model by applying a fifth-order polynomial model having initialized parameters to a current profile for at least one valve and optimizing the parameters for the fifth-order polynomial model via least mean squares estimation.

[0051] In a twenty-fourth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, instructions, when executed, cause a system to generate a current profile for at least one valve by normalizing measured current values ​​for the at least one valve using a maximum current value.

[0052] In a twenty-fifth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the instructions, when executed, cause the system to normalize measured current values ​​by identifying a current rise time for at least one valve based on measured current values ​​of the at least one valve, and determining a maximum current for normalizing the measured current values ​​for the at least one valve based on the current rise time for the at least one valve.

[0053] In a 26th aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the trained classification model is one or more of a support vector machine trained using a reference dataset comprising a plurality of reference current profiles having known operating conditions, or a logistic regression model trained using a reference dataset comprising a plurality of reference current profiles having known operating conditions.

[0054] In a twenty-seventh aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the instructions, when executed, further cause the system to: before applying the respective polynomial models to the trained classification model, further receive a first reference data set comprising a plurality of reference current profiles indicative of successful operation; receive a second reference data set comprising a plurality of reference current profiles indicative of unsuccessful operation; 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 the trained classification model after convergence based on the optimized decision boundaries.

[0055] In a twenty-eighth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a medical fluid system includes a plurality of valves, each valve including a housing, a coil, and a plunger, each valve configured to allow flow of medical fluid through a tube by energizing a corresponding coil and moving a corresponding plunger within the corresponding housing, and each valve configured to close flow of medical fluid through the tube by de-energizing the corresponding coil and moving the corresponding plunger in the opposite direction within the corresponding housing to occlude the corresponding tube, at least one processor, and at least one memory storing instructions, The instructions, when executed by the at least one processor, cause the at least one processor to receive measured current values ​​at a predetermined sampling rate for a predetermined duration during stall of at least one of the plurality of valves, generate a current profile for the at least one valve based on the respective measured current values ​​for the at least one valve, generate a polynomial model for the at least one valve based on the respective current profile for the at least one valve, and apply the respective polynomial model to the trained classification model for the at least one valve to assess a stall condition for the at least one valve.

[0056] In a 29th aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the stop status indicates one of a successful stop or a failed stop, and the instructions, when executed, further cause the system to generate an alert indicating a malfunction of a valve associated with the failed stop based on the stop status indicating a failed stop.

[0057] In a thirtieth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a method for evaluating functionality of solenoid valve actuation includes receiving, by a control unit of a medical fluid system having at least one processor, measured current values ​​at a predetermined sampling rate for a predetermined duration during actuation of at least one of a plurality of valves controlled by the control unit, each valve comprising a housing, a coil, and a plunger, each valve configured to actuate flow of medical fluid through a tube by energizing a corresponding coil and moving a corresponding plunger within a corresponding housing, and each valve configured to close flow of medical fluid through a tube by de-energizing a corresponding coil and moving a corresponding plunger in an opposite direction within a corresponding housing to occlude a corresponding tube, generating a current profile for the at least one valve based on the respective measured current values ​​for the at least one valve; generating a polynomial model for the at least one valve based on the respective current profile for the at least one valve; and applying the respective polynomial model to the trained classification model for the at least one valve to assess an operating state for the valve.

[0058] In a thirty-first aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the operation status indicates one of successful operation or failed operation, and the method further includes generating an alert indicating a malfunction of a valve associated with the failed operation based on the operation status indicating the failed operation.

[0059] In a thirty-second aspect of the present disclosure, which may be combined with any other aspect or portion thereof, generating the polynomial model includes applying a fifth-order polynomial model having initialized parameters to a current profile of at least one valve, and optimizing the parameters for the fifth-order polynomial model via least mean squares estimation.

[0060] In a thirty-third aspect of the present disclosure, which may be combined with any other aspect or portion thereof, generating a current profile for the at least one valve includes normalizing measured current values ​​for the at least one valve using a maximum current value.

[0061] In a thirty-fourth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, normalizing the measured current value for the at least one valve includes identifying a current rise time for the at least one valve based on the measured current value of the at least one valve, and determining a maximum current for normalizing the measured current value for the at least one valve based on the current rise time for the at least one valve.

[0062] In a thirty-fifth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the trained classification model is one or more of a support vector machine trained using a reference dataset comprising a plurality of reference current profiles having known operating conditions, or a logistic regression model trained using a reference dataset comprising a plurality of reference current profiles having known operating conditions.

[0063] In a thirty-sixth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the method further includes, before applying the respective polynomial models to the trained classification model, receiving a first reference data set comprising a plurality of reference current profiles indicative of successful operation, receiving a second reference data set comprising a plurality of reference current profiles indicative of unsuccessful operation, labeling the first reference data set and the second reference data set with positive and negative outputs, respectively, iteratively testing one or more decision boundaries separating the first reference data set and the second reference data set, and generating the trained classification model after convergence based on the optimized decision boundaries.

[0064] In a 37th aspect of the present disclosure, which may be combined with any other aspect or portion thereof, a method for evaluating functionality of a solenoid valve stop includes: receiving, by a control unit of a medical fluid system having at least one processor, measured current values ​​at a predetermined sampling rate for a predetermined duration during stop of at least one of a plurality of valves controlled by the control unit, wherein each valve has a housing, a coil, and a plunger, and each valve is configured to activate a flow of medical fluid through a tube by energizing a corresponding coil and moving 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 and moving the corresponding plunger in an opposite direction within the corresponding housing to occlude the corresponding tube; generating a current profile for the at least one valve based on the respective measured current values ​​for the at least one valve; generating a polynomial model for the at least one valve based on the respective current profile for the at least one valve; and applying the respective polynomial model to a trained classification model for the at least one valve to evaluate a stop state of the valve.

[0065] In a thirty-eighth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, the stop status indicates one of a successful stop or a failed stop, and the method further includes generating an alert indicating a malfunction of a valve associated with the failed stop based on the stop status indicating the failed stop.

[0066] In a thirty-ninth aspect of the present disclosure, which may be combined with any other aspect or portion thereof, one or more non-transitory computer-readable media store instructions that, when executed by at least one processor, receive measured current values ​​at a predetermined sampling rate for a predetermined duration during operation of at least one of a plurality of valves controlled by a control unit of a medical fluid system, each valve including a corresponding housing, a corresponding coil, and a corresponding plunger, each valve configured to actuate flow of the medical fluid through a tube by energizing the corresponding coil and moving the corresponding plunger within the corresponding housing, each valve including a corresponding and configured to close the flow of medical fluid through the tubing by de-energizing the coil and moving the corresponding plunger in the opposite direction within the corresponding housing to occlude the corresponding tubing; and causing the at least one processor to: generate a current profile for the at least one valve based on the respective measured current values ​​for the at least one valve; generate a polynomial model for the at least one valve based on the respective current profile for the at least one valve; and apply the respective polynomial model to the trained classification model for the at least one valve to evaluate an operating state for the at least one valve.

[0067] In a fortieth aspect of the present disclosure that may be combined with any other aspect or portion thereof, the operation state indicates one of successful operation or failed operation, and the non-transitory computer-readable medium is configured to generate an alert indicating a malfunction of a valve associated with the failed operation based on the operation state indicating the failed operation. In a fortieth aspect of the present disclosure that may be combined with any other aspect or portion thereof, any of the features, functions, and alternatives described in connection with any one or more of Figures 1-14 may be combined with any of the features, functions, and alternatives described in connection with any other of Figures 1-14.

[0068] In light of the above aspects and the disclosure described herein, it is an advantage of the present disclosure to provide a medical fluid system with improved solenoid valve operation.

[0069] Another advantage of the present disclosure is to provide a medical fluid system with a solenoid valve method that reduces noise caused by valve operation.

[0070] A further advantage of the present disclosure is to provide a medical fluid system with a solenoid valve method that reduces noise without requiring additional equipment.

[0071] Yet another advantage of the present disclosure is to provide a medical fluid system with a solenoid valve method that ensures proper opening and closing of the solenoid valve.

[0072] Yet another advantage of the present disclosure is to provide a medical fluid system with a solenoid valve method that ensures proper opening and closing of the solenoid valve without requiring additional equipment.

[0073] Additional features and advantages are described in and will be apparent from the following detailed description and drawings. The features and advantages described herein are not all-inclusive, and in particular, many additional features and advantages will be apparent to those skilled in the art upon consideration of the drawings and description. No particular embodiment is required to possess all of the advantages enumerated herein, and it is expressly contemplated that each advantageous embodiment may be separately claimed. Furthermore, it should be noted that the language used herein has been selected primarily for readability and instructional purposes, and not to limit the scope of the inventive subject matter. [Brief explanation of the drawings]

[0074] [Figure 1] FIG. 1 is a cross-sectional schematic diagram of one embodiment for an automated PD system with solenoid valve actuation of the present disclosure.

[0075] [Figure 2]FIG. 2 is a cross-sectional elevation view of one embodiment of a two-way valve that can be used in the systems and associated methods of the present disclosure.

[0076] [Figure 3] FIG. 3 is a cross-sectional elevation view of one embodiment of a three-way valve that can be used in the systems and associated methods of the present disclosure.

[0077] [Figure 4] FIG. 4 is a circuit simulation of a system for reducing noise generated by solenoid valve operation in a medical fluid system using NPN transistors in accordance with a non-limiting embodiment of the present disclosure.

[0078] [Figure 5] FIG. 5 is a block diagram illustrating a system and method for reducing noise generated by solenoid valve operation in a medical fluid system using NPN transistors in accordance with a non-limiting embodiment of the present disclosure.

[0079] [Figure 6] FIG. 6 is a circuit diagram illustrating a system for reducing noise generated by solenoid valve operation in a medical fluid system using MOSFETs according to a non-limiting embodiment of the present disclosure.

[0080] [Figure 7A] FIG. 7A is a graph illustrating control signals and applied voltages for reducing noise generated by solenoid valve operation in a medical fluid system using MOSFETs according to a non-limiting embodiment of the present disclosure.

[0081] [Figure 7B] FIG. 7B is a graph illustrating applied voltages for reducing noise generated by solenoid valve operation in a medical fluid system using pulse width modulation (“PWM”) in accordance with a non-limiting embodiment of the present disclosure.

[0082] [Figure 8]FIG. 8 is a block diagram illustrating a system and method for reducing noise generated by solenoid valve operation in a medical fluid system using MOSFETs according to a non-limiting embodiment of the present disclosure.

[0083] [Figure 9] FIG. 9 is a block diagram illustrating a system and method for reducing noise generated by solenoid valve operation in a medical fluid system using pulse width modulation (“PWM”) in accordance with a non-limiting embodiment of the present disclosure.

[0084] [Figure 10A] FIG. 10A is a current profile of a solenoid valve with successful actuation according to an exemplary embodiment of the present disclosure.

[0085] [Figure 10B] FIG. 10B is another current profile of a solenoid valve with successful actuation according to an exemplary embodiment of the present disclosure.

[0086] [Figure 10C] FIG. 10C is a current profile of a solenoid valve having a successful shutdown according to an exemplary embodiment of the present disclosure.

[0087] [Figure 11] FIG. 11 is a flowchart of an exemplary process for evaluating functionality of solenoid valve actuation according to an exemplary embodiment of the present disclosure.

[0088] [Figure 12] FIG. 12 is a sampled normalized current profile of a solenoid valve having successful actuation according to an exemplary embodiment of the present disclosure.

[0089] [Figure 13] FIG. 13 is a sampled normalized current profile of a solenoid valve having a failed actuation according to an exemplary embodiment of the present disclosure.

[0090] [Figure 14] FIG. 14 is a flowchart of an exemplary process for training a classification model for assessing functionality of solenoid valve actuation according to an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0091] (System Overview) Referring now to the drawings, and in particular to FIG. 1 , an exemplary system 10 incorporating solenoid valve operation of the present disclosure is illustrated. 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. Control unit 100 controls all electrical, fluid flow, and heating components of system 10 and receives outputs from all sensors in system 10. System 10 in the illustrated embodiment includes durable, reusable components that come into contact with medical fluids, such as PD fluids, requiring the PD machine or cycler 20 to be disinfected between treatments, e.g., by thermal disinfection.

[0092] System 10 of FIG. 1 includes an in-line resistance heater 56, reusable supply lines or tubing 52a1-52a4 and 52b, an air trap 60 operating in conjunction with upper and lower level sensors 62a and 62b, respectively, an air trap valve 54d, a vent valve 54e located along vent line 52e, reusable line or tubing 52c, a dialysate pump 70, temperature sensors 58a and 58b, and pressure sensors 78a, 78b1, 78b2 and 78b3. The system includes reusable patient-side tubing or lines 52f and 52g with respective valves 54f and 54g, dual-lumen reusable patient line 28, hose reel 80 for retracting patient line 28, reusable drain tube or line 52i extending to drain line connector 34 and having drain line valve 54i, and reusable recirculation or disinfection tubing or lines 52r1 and 52r2 operating with respective disinfection valves 54r1 and 54r2. A third recirculation or disinfection tubing or line 52r3 extends between disinfection connectors 30a and 30b for use during disinfection. A fourth recirculation or disinfection tubing or line 52r4 extends between disinfection connectors 30c and 30d for use during disinfection.

[0093] System 10 further includes PD fluid containers or bags 38a-38c (e.g., holding the same or different formulations of PD fluid) that connect to distal ends 24d of reusable PD fluid lines 24a-24c, respectively. System 10d further includes a fourth PD fluid container or bag 38d that connects to distal ends 24d of reusable PD fluid line 24e. Fourth PD fluid container or bag 38d may hold the same or a different type of PD fluid (e.g., icodextrin) as provided in PD fluid containers or bags 38a-38c. Reusable PD fluid lines 24a-24c and 24e, in one embodiment, extend through openings (not shown) defined or provided by housing 22 of cycler 20.

[0094] In the illustrated embodiment, system 10 includes four disinfection connectors 30a-30d for connecting to distal ends 24d of reusable PD fluid lines 24a-24c and 24e, respectively, during disinfection. System 10 also provides a patient line connector 32 including an internal lumen, e.g., a U-shaped lumen, that directs fresh or used dialysate from one PD fluid lumen to the other PD fluid lumen of dual-lumen reusable patient line 28. Reusable supply tubes or lines 52a1-52a4 communicate with reusable supply lines 24a-24c and 24e, respectively. Reusable supply tubes or lines 52a1-52a3 operate with valves 54a-54c, respectively, to allow PD fluid to be drawn into cycler 20 from desired PD fluid containers or bags 38a-38c. Three-way valve 94a in the illustrated example allows control unit 100 to select between (i) 2.27% (or other) glucose dialysate from container or bag 38b or 38c and (ii) icodextrin from container or bag 38d. In the illustrated embodiment, icodextrin from container or bag 38d is connected to a normally closed port of three-way valve 94a.

[0095] 1 illustrates that system 10 includes and uses a disposable filter set 40 in fluid communication with the unused and used PD fluid lumens of dual lumen reusable patient line 28. Disposable filter set 40 includes a disposable connector 42 that connects to the distal end 28d of reusable patient line 28. Disposable filter set 40 includes a connector 48 that connects to a patient transfer set. Disposable filter set 40 further includes a sterilizing-grade filter membrane 46 that further filters the unused PD fluid.

[0096] System 10, in one embodiment, is configured such that during filling, drain line 52i is fluidly connected downstream of dialysate pump 70. In this manner, if drain valve 54i fails or somehow leaks during patient filling of patient P, unused PD fluid is forced into disposable drain line 36 instead of potentially drawing used PD fluid into pump 70. Disposable drain line 36, in one embodiment, is removed for disinfection, and drain line connector 34 is capped via cap 34c.

[0097] System 10 further includes a leak detection pan 82 located at the bottom of housing 22 of cycler 20 and a corresponding leak detection sensor 84 that outputs to control unit 100. In the illustrated example, system 10 is provided with an additional pressure sensor 78c located upstream of dialysate pump 70, which allows measurement of the suction pressure of pump 70 and helps control unit 100 more accurately determine pump volume. The additional pressure sensor 78c in the illustrated embodiment is located along vent line 52e, which may be filled with air or a mixture of air and PD fluid, but which should nevertheless be at the same negative pressure as the PD fluid located in PD fluid line 52c.

[0098] 1 includes redundant pressure sensors 78b1 and 78b2, one output of which is used for pump control as described herein, and the other pressure sensor output is a safety or watchdog output to ensure the control pressure sensor is reading accurately. Pressure sensors 78b1 and 78b2 are located along a line that includes third recirculation valve 54r3. In yet another example, system 10 may use one or more crosses, marked with an X in FIG. 1, which may (i) reduce the overall amount and volume of reusable internal tubing, (ii) reduce the number of valves required, and (iii) minimize the portion of the fluid circuit shared by both fresh and used PD fluid.

[0099] The system 10 in the example of FIG. 1 further includes an acid source, such as a citric acid container or bag 66. The citric acid container or bag 66 is in selective fluid communication with a second three-way valve 94b via a citric acid valve 54m located along a 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 citric (or other) acid does not reach the treatment fluid line during treatment. Instead, citric (or other) acid is used during disinfection.

[0100] It should be understood that system 10 is not required to (i) be a dialysis system or (ii) use redundant or durable components that are sanitized between uses in order to employ the sensor thermoelectric heating of the present disclosure. Instead, system 10 may be any type of medical fluid system and may use a disposable set having disposable pump portions that contact the corresponding medical fluid. In the primary examples described herein, solenoid valves are described as operating in a PD device or cycler 20.

[0101] Any one or more or all of valves 54a-54h, 54m, and 54r1-54r4, 94a and 94b may be solenoid valves, which may be of a type that uses an internal fluid path that opens or closes depending on whether a coil is energized. This type of solenoid valve is well suited to durable or reusable versions of PD devices or cyclers. Another type of solenoid valve for valves 54a-54h, 54m, and 54r1-54r4 operates by opening or closing flexible tubing depending on whether a coil is energized. This type of solenoid valve is well suited to versions of PD devices or cyclers that operate with disposable sets, but may also be used in durable versions of PD devices or cyclers that have internal flexible tubing for operation with the solenoid valve.

[0102] Referring now to FIG. 2, one suitable two-way solenoid valve 154 is shown for two-way valves 54a-54h, 54m, and 54r1-54r4. Valve 154 of FIG. 2 is of a type that uses an internal fluid path that opens or closes depending on whether a coil is energized. Valve 154 includes two main sections: a solenoid section 160 and a valve section 180. Solenoid section 160 includes a solenoid housing 162. Solenoid housing 162 supports a coil 164 that extends around an inner wall 162i of housing 162, and coil 164 is energized to move or translate a solenoid plunger 166. A compression spring 168 is provided and is positioned to bias plunger 166 to a closed position when energy is removed from coil 164.

[0103] FIG. 2 shows that plunger 166 has a contact end 166e. Additionally, core portion 162c of solenoid housing 162 is provided with stopper 162s. When coil 164 is energized, a magnetic field is induced adjacent solenoid plunger 166 from right to left within inner wall 162i of housing 162, thereby causing contact end 166e of plunger 166 to abut stopper 162s, providing a travel end for plunger 166 in the open position. The abutting contact between end 166e and stopper 162s can cause noise, which can be problematic for PD patients, especially when they are trying to sleep. Described herein are structures and related methodologies that help reduce the noise caused by the abutting contact between end 166e and stopper 162s.

[0104] 2 shows the two-way solenoid valve 154 in a closed state or with no fluid flow. Here, the coil 164 is de-energized, causing the compression spring 168 to urge the contact end 166e of the plunger 166 away from the stopper 162s provided in the core portion 162c of the solenoid housing 162. The lever end 166l of the plunger 166 is translated such that the lever 170 rotatably held on the lever end 166l of the plunger 166 is tilted to close the fluid path located within the valve portion 180 of the valve 154.

[0105] The valve portion 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 stopper 188, which can be made of a medically safe, compressible (sealable) rubber, such as silicone. In the closed position shown in FIG. 2, when the coil 164 is de-energized and the compression spring 168 is extended, the lever 170 pivots the membrane or stopper 188, contacting and sealing the inside of the outlet 186, e.g., the angled port 186p, to prevent fluid flow. When the coil 164 is energized, the plunger 166 moves left, compressing the spring 168 and pivoting the lever 170, which stops the membrane or stopper 188 in a substantially vertical position away from the angled port 186p of the outlet 186. Here, fluid, such as water or PD fluid, can flow from fluid inlet 184 , around membrane or stopper 188 , and through fluid outlet 186 .

[0106] When the valve 154 is closed and the membrane or stopper 188 is sealed against the tilted port 186p of the fluid outlet 186, the fluid pressure downstream from the outlet 186 is lower than the fluid pressure upstream of the fluid inlet 184. The pressure delta helps seal the membrane or stopper 188 against the tilted port 186p, so that the compression spring 168 does not need to provide the force necessary (or all of the force necessary) to keep the membrane or stopper sealed against the tilted port. The primary 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 delta that helps seal the membrane or stopper 188 against the tilted port 186p when the valve 154 is to be closed also counters the magnetic force induced when the coil 164 is energized. Structures and related features are described herein to ensure that the valve 154 opens properly when it is supposed to.

[0107] Referring now to FIG. 3, a three-way solenoid valve 194 suitable for the three-way valves 94a and 94b is shown. The valve 194 of FIG. 3 is of a type that uses an internal fluid path that opens or closes depending on whether a coil is energized. Like valve 154, the valve 194 includes two main sections: a solenoid section 200 and a valve section 220. The solenoid section 200 is essentially the same as the solenoid section 160 of valve 154. The solenoid section includes a solenoid housing 202 that supports a coil 204 that is energized to move or translate a solenoid 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 stopper 202s provided in a core portion 202c of the solenoid housing 202 when the coil 204 is energized. The abutting contact between end 206e and stopper 202s causes noise, which can be problematic for a PD patient, especially when the patient is trying to sleep. Described herein are structures and associated methodologies that help reduce the noise caused by abutting contact between end 206e and stopper 202s.

[0108] 3 illustrates the normally closed state of the three-way solenoid valve 194. Here, the coil 204 is de-energized, causing the compression spring 208 to urge the contact end 206e of the plunger 206 away from the stopper 202s provided in the core portion 202c of the solenoid housing 202. The lever end 206l of the plunger 206 is translated such that the lever 210 rotatably held on the lever end 206l of the plunger 206 is tilted to close the fluid path located within the valve portion 220 of the valve 194.

[0109] Valve portion 220 is where three-way valve 194 differs from two-way valve 154. Valve portion 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. Attached to the portion of lever 210 that extends into valve housing 222 is a membrane or stopper 230, which may also be made of a medically safe, compressible (sealable) rubber such as silicone. In the normally closed position of FIG. 2, with coil 204 de-energized and compression spring 208 extended, lever 210 pivots membrane or stopper 230 to contact and seal the inside of normally closed fluid outlet 226, e.g., angled port 226p, preventing fluid flow through the normally closed outlet. When coil 204 is energized, plunger 206 moves to the left, compressing spring 208 and pivoting lever 210, causing membrane or stopper 230 to move away from angled port 226p of normally closed fluid outlet 226 and instead contact and seal the inside of normally open fluid outlet 228, e.g., angled port 228p, preventing fluid flow through the normally open outlet. In the normally closed state, three-way valve 194 allows fluid, such as water or PD fluid, to flow from fluid inlet 224 through normally open fluid outlet 228. In the normally open state, three-way valve 194 allows fluid, such as water or PD fluid, to flow from fluid inlet 224 through normally closed fluid outlet 228.

[0110] The higher fluid pressure through fluid inlet 224 helps seal membrane or stopper 230 against both normally closed port 226p and normally open port 228p, and the lower pressure at normally closed fluid outlet 226 and normally open fluid outlet 228. However, it should also be understood that the pressure delta that helps seal membrane or stopper 230 against angled ports 226p, 228p counters (i) the magnetic force induced when coil 164 is energized to open normally closed fluid outlet 226, and (ii) the force of compression spring 208 when coil 164 is de-energized to open normally open fluid outlet 226. Structures and related features are described herein to ensure that normally closed fluid outlet 226 is properly opened when it is intended to be.

[0111] (Solenoid valve methodology for reducing noise) As previously mentioned, a reliable methodology for reducing noise generated by solenoid valves in medical fluid delivery operations is desirable and needed. Noise reduction is particularly important for peritoneal dialysis systems, which operate close to the patient and may be performed at night while the patient is asleep. A desirable PD system maintains noise levels below 33 decibels. Various embodiments of the present disclosure describe systems and methods for reducing noise in PD systems that use solenoid valves. In particular, various embodiments describe systems and methods for controlling the movement of a solenoid valve to minimize the amount of sound (noise) generated during impacts during valve activation and deactivation. The systems and methods generally involve slowing the movement of a valve plunger within a valve coil. Modifications that slow the valve movement result in fewer collisions with the valve housing, producing lower levels of impact noise. Various embodiments described herein include the use of low-pass filtering, NPN transistors, MOSFETs, and pulse-width modulation, among others.

[0112] In at least one embodiment, a method for slowing valve plunger movement includes ramping up the voltage applied to the solenoid coil (e.g., during valve actuation) and / or ramping down the voltage applied to the solenoid coil (e.g., during valve deactivation). In one aspect, a low-pass filter can be applied to the existing voltage application to provide the ramp-up and / or ramp-down effect. Because steady-state operation of the valve may typically use, in one example, about 0.3 A, the resistor may need to be small and the capacitor size may need to be large. For example, the capacitor size to obtain a time constant of about 25 ms may be about 25 mF if a 1 ohm resistor is selected.

[0113] In at least one embodiment, a transistor may be used to ramp up and / or ramp down the voltage applied to the valve's solenoid coil to slow plunger movement and reduce noise. In some aspects, the transistor may provide linear control over the voltage applied to the coil. Different variations of transistors (e.g., NPN transistors, MOSFET transistors, etc.) may offer different capabilities and positive aspects for effectively reducing solenoid valve noise, which will be discussed in connection with FIGS. 4 through 8.

[0114] 4 is a circuit simulation 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. The system may include a valve 414 of a PD system (e.g., valve 154 or valve 194 described above) electrically controlled by an NPN transistor 412. For example, as shown in FIG. 4 , a power supply 406 (e.g., an NPU) may control the NPN transistor 412 through a control signal (e.g., an ON / OFF signal). The control signal may be generated based on a power supply voltage setting 404. The control signal sent to the NPN transistor may comprise and / or generate an input current to the NPN transistor (e.g., as shown in current ramp profile 402). The input current may cause the NPN transistor to transition the valve 414 to energize the solenoid coil. If the input current remains low (e.g., so that the input current does not exceed the non-saturation region of NPN transistor 412), the voltage applied to the solenoid coil can be ramped up by ramping up the current to NPN transistor 412 (e.g., as shown by current ramp profile 402). This behavior is similar to a low-pass filter, which eliminates the need to provide large capacitance or resistance at the solenoid coil. In some embodiments, the system can further include a solver device 408, which is used to determine when to provide the necessary signal to NPN transistor 412 to cause the valve to ramp up or down the voltage applied to the solenoid coil. Simulation of the circuit can cause effects in the physical domain (e.g., via valve 414). For example, NPN transistor 412 can cause valve 414 to apply a force to a plunger, causing the plunger to move.

[0115] 5 is a block diagram illustrating a system and method for reducing noise generated by solenoid valve operation in a medical fluid system using NPN transistors according to a non-limiting embodiment of the present disclosure. The system may include a control unit 100 of a PD system 10, which may further include a memory 102 and a processor 104, as described above. The system may further include a plurality of NPN transistors 504 configured to control a plurality of valves 510 (e.g., the above-described valves 154 or 194) in response to control signals received from the control unit 100. As described above, the plurality of valves 510 may include solenoid valves (e.g., valves 154 or 194) used by the PD system to control the flow of fresh and used PD fluid. Accordingly, each valve 510 may include a corresponding housing 514, a respective solenoid coil 512, and a corresponding plunger 516. Each valve 510 may be configured to actuate fluid flow through tubing of the PD system by applying a voltage to a respective solenoid coil 512 via a respective NPN transistor 504, causing a corresponding plunger 516 to move within a corresponding housing 514. Each valve may also be configured to close fluid flow through tubing by removing (e.g., reducing) a voltage to a corresponding coil 512 via a respective NPN transistor 504, causing a corresponding plunger 516 to move in the opposite direction relative to the corresponding housing 514 (e.g., to occlude the corresponding tube).

[0116] To reduce noise associated with valve actuation (e.g., valve opening) of a given valve, the control unit 100 may be configured to send a low control signal (e.g., via the processor 104 processing computer-executable instructions stored in the memory 102) to an NPN transistor 504 associated with the valve 510 (block 502). The low control signal may cause an input current to the NPN transistor 504 to ramp up (block 506). The ramp up of the input current to the NPN transistor 504 may cause a voltage applied to the corresponding coil 512 of the valve 510 to ramp up (block 508). As previously discussed, the ramp up of the voltage applied to the solenoid coil 512 causes the plunger 516 to move more slowly during actuation (e.g., as opposed to a sudden application of voltage). Thus, the slower movement may reduce sound generated by the corresponding plunger of the valve 510 (block 518).

[0117] To reduce noise associated with valve deactivation (e.g., valve closure) of a given valve, the control unit 100 may be configured to turn off a low control signal to the NPN transistor 504 associated with the valve (block 520). Turning off the control signal may cause an input current supplied to the NPN transistor 504 to ramp down (block 522). The ramp down of the input current to the NPN transistor 504 may cause a voltage applied to the corresponding coil 512 of the valve 510 to ramp down (block 524). As previously mentioned, the ramp down of the voltage applied to the solenoid coil 512 causes the plunger 516 to move more slowly in the opposite direction from the housing 514 during deactivation (as opposed to, e.g., a sudden termination of the voltage). Thus, the slower movement may reduce sound generated by the corresponding plunger of the valve 510 (block 526).

[0118] A MOSFET is another transistor that can be used to slow the movement of the plunger in a solenoid valve, thus reducing noise. Additionally, using a MOSFET to control the voltage applied to the solenoid coil can overcome the unwanted heat generated by the relatively high resistance of an NPN transistor.

[0119] 6 is a circuit diagram of a system for reducing noise generated by solenoid valve operation in a medical fluid system using MOSFETs according to a non-limiting embodiment of the present disclosure. The system's circuitry may use P-channel MOSFETs 614a and 614b to facilitate the slow application (e.g., by ramping up) and slow removal (e.g., by ramping down) of voltage to the solenoid coil 605 of the valve 604. The control signal 602 may include a simple digital output from the control unit 100 and / or other digital circuitry. When the digital control signal is high (e.g., "1" and / or "true"), one or both of the MOSFETs 614a and 614b are driven such that the applied voltage is equal to the input voltage V in In some aspects, the voltage applied to the solenoid coil 605 may be ramped up until it reaches a voltage equal to V. inmay refer to the threshold voltage required for the valve to fully actuate (e.g., by moving the plunger all the way to its end point within the housing). When the digital control signal generated by the control unit 100 goes low (e.g., “0” or “false”), the applied voltage may slowly ramp down toward a voltage of 0V. The up-ramping and down-ramping times can be adjusted by changing the values ​​of one or more resistors and capacitors in the circuit, such as 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 may be arranged in series, for example, as shown in the circuit of FIG. 6. The ramping up and ramping down of the voltage applied to the solenoid coil 605 may add turn-on and turn-off delays, respectively, to the control of the solenoid coil 605. To shorten this delay, an initial ramp offset circuit may be added to the circuit to generate an additional voltage of an offset value applied to the coil 605. This offset value can be set to a voltage close to the lowest voltage that one or more of MOSFETs 614a, 614b applies to the solenoid coil 605. In one embodiment, the offset value of the lamp offset voltage can be set by adjusting feedback resistor R5 610 relative to resistors R2 606 and R4 608. An example control signal sent to MOSFET 614b and an example voltage applied to the solenoid coil 605 can be seen in FIG. 7A.

[0120] 7A is a graph illustrating a control signal 704 and an applied voltage 702 for reducing noise generated by solenoid valve operation in a medical fluid system 10 using a MOSFET according to a non-limiting embodiment of the present disclosure. As previously described, the control signal 704 may be a digital signal generated by the control unit 100 and transmitted to a MOSFET to cause the MOSFET to generate the applied voltage 704. As shown in FIG. 7A, the high level (i.e., supply level) of the digital control signal 704 is 3 V, while the low level (i.e., reference level) of the digital control signal 704 is 0 V. In response to the high digital control signal 704, the MOSFET allows the applied voltage 702 to ramp up (as indicated by the positive slope from approximately 0 ms to approximately 210 ms). However, when the digital control signal 704 is set to a low level (e.g., 0 V), the MOSFET causes the applied voltage 702 to ramp down (as indicated by the negative slope from approximately 500 ms to 650 ms). The relatively vertical increases and decreases in applied voltage 702 (at 0 ms and 500 ms, respectively) may be due to offset voltages applied to the solenoid coil to overcome delays caused by ramp-up and ramp-down, respectively.

[0121] 7B is a graph illustrating an applied voltage for reducing noise generated by solenoid valve operation in a medical fluid system using pulse width modulation (“PWM”) in accordance with a non-limiting embodiment of the present disclosure. The applied voltage may be responsive 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., activate) the solenoid valve. In response to the command, the I / O driver may apply and ramp up (706) a PWM voltage to a solenoid coil associated with the valve. For example, the I / O driver may ramp up the PWM voltage from approximately 6 V to 24 V over a period of 2 ms to 400 ms. The applied voltage may cause the plunger of the valve to move toward the housing. After the plunger in the valve reaches its end point (e.g., within the housing) (e.g., which may occur before or during the phase shown as "hit" 708), the PWM duty cycle can be reduced, which reduces power consumption and heat generation in the PD system 10. For example, the control unit 100 may instruct the I / O driver (e.g., via a second control signal) to ramp down the PWM signal applied to the corresponding coil until it reaches a predetermined voltage. For example, the I / O driver may maintain the PWM signal at 12 V (e.g., as shown by "hold" 710 from 600 ms to 1200 ms in FIG. 7B). When the valve is to be stopped (e.g., closed and / or shut off), the I / O driver may ramp down the PWM to 0 V 712 (e.g., as shown from 1200 ms to 1400 ms in FIG. 7B). In some embodiments, if the I / O driver slowly ramps up the PWM voltage, as shown, the plunger in the valve may reach its end point within the housing during the ramp-up phase 706. The volume level associated with hitting the endpoint may be lower because the plunger may hit the endpoint as a result of the lower power applied to the solenoid valve. Additionally, the full power level at the stage shown as "Hit" 708 may ensure that the plunger hits the seal even with increased load.From this stage onwards, power consumption can be reduced (eg, as in "hold" stage 710).

[0122] FIG. 8 is a block diagram illustrating a system and method for reducing noise generated by solenoid valve operation in a medical fluid system using MOSFETs according to a non-limiting embodiment of the present disclosure. The system may include a control unit 100 of a PD system 10, which may further include a memory 102 and a processor 104, as described above. The system may further 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 may include solenoid valves 154, 194 ( FIGS. 2 and 3 ) used by the PD system 10 to control the flow of fresh and used PD fluid. Accordingly, each valve 510 may include a corresponding housing 514, a respective solenoid coil 512, and a corresponding plunger 516. Each valve 510 may be configured to actuate fluid flow through the tubing of the PD system 10 by applying a voltage to the respective solenoid coil 512 via the respective MOSFET 804, thereby moving the corresponding plunger 516 within the corresponding housing 514. Each valve may also be configured to close the flow of fluid through the tube by not applying (e.g., reducing) a voltage to a corresponding coil 512 via a respective MOSFET 804 to move a corresponding plunger 516 in the opposite direction of a corresponding housing 514 (e.g., occlude the corresponding tube).

[0123] To reduce noise associated with valve actuation (e.g., valve opening) of a given valve, the control unit 100 may be configured to transmit (e.g., via the processor 104 processing computer-executable instructions stored in the memory 102) a high digital control signal (e.g., a digital signal corresponding to a “high” level, a supply voltage, and / or a binary output of “1”) to a MOSFET 804 associated with the valve 510 (block 802). As will be appreciated, a MOSFET, unlike an NPN transistor, requires less power for its gate to operate (e.g., to actuate the MOSFET) and therefore may not require a ramp-up of input current 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 discussed, the ramp-up of the voltage applied to the solenoid coil 512 causes the plunger 516 to move more slowly during actuation (e.g., as opposed to a sudden application of voltage). Thus, the slower movement may reduce sound generated by the corresponding plunger of the valve 510 (block 810). In some embodiments, a slow ramp-up of the voltage applied to the coil may cause undesirable delays in valve actuation, therefore an offset voltage may be applied to the solenoid coil 512 via a ramp offset circuit (block 808).

[0124] To reduce noise associated with valve deactivation (e.g., valve closure) of a given valve, the control unit 100 may be configured to transmit a low digital control signal (e.g., a digital signal corresponding to a “low” level, a reference voltage 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 ramp-down voltage to the corresponding coil 512 of the valve 510 (block 814). As previously discussed, the ramp-down of the voltage applied to the solenoid coil 512 causes the plunger 516 to move more slowly during deactivation (e.g., as opposed to a sudden removal of the voltage). Thus, the slower movement may reduce sound generated by the corresponding plunger of the valve 510 (block 818). In some embodiments, a slow ramp-down of the voltage applied to the coil may cause an undesirable delay in the actuation of the valve. Therefore, an offset voltage may be released from the solenoid coil 512 via a ramp-offset circuit (block 816).

[0125] In at least one embodiment, pulse width modulation ("PWM") may be used to ramp up and / or ramp down the voltage applied to the valve's solenoid coil to slow plunger movement and reduce noise. Furthermore, PWM-based techniques may overcome problems caused by relying on transistors to gradually decrease (e.g., ramp down) the voltage applied to the solenoid coil during deactivation. For example, lowering the applied voltage may induce a lower magnetic field in the solenoid coil, resulting in lower force acting on the plunger. Because the valve may be operating against low or high pressure, the valve may require full force to change from a closed state to an open state during activation, or from an open state to a closed state during deactivation. Systems and methods relying on PWM signals for valve activation and deactivation may overcome these problems. Furthermore, as described herein, controlling the activation and / or deactivation of a valve via methods relying on pulse width modulation may also include ramping up and / or ramping down the voltage applied to the solenoid coil, but only during transition periods. After a transition period (e.g., during the start of valve actuation or the start of valve deactivation), the pulse width modulation technique ultimately reduces the total input voltage V over a sustained period to ensure the plunger moves properly to its intended end point (e.g., into the housing during actuation, or toward the position that closes the valve during deactivation). in The method may include applying

[0126] The application of PWM for valve actuation may involve pulsing (rapidly switching on and off) voltage to the solenoid coil while ramping up the voltage until the plunger moves. The application of PWM for valve deactivation may involve decreasing pulses of voltage to the solenoid coil while ramping down the voltage until the plunger moves. This may allow for slower plunger movement, lower impact when the valve is actuated / deactuated, and therefore reduced noise. Another advantage of this approach is that PWM is available during normal operation. Therefore, using PWM to actuate and / or deactuate the valve may lower overall power demands and keep the PD system 10 cooler during operation.

[0127] In at least one embodiment, an exemplary power-on / power-off cycle for a solenoid valve utilizing PWM includes the control unit 100 transmitting a command (e.g., via a control signal) to an input / output (I / O) driver associated with the valve to energize (e.g., activate) the valve. In response to the command, the I / O driver may apply and ramp up a PWM voltage to a solenoid coil associated with the valve. For example, the I / O driver may ramp up the PWM voltage from 0% to 100% over 2 ms to 75 ms (e.g., 2 ms to 10 ms). The applied voltage may cause the plunger of the valve to move toward the housing. After the plunger in the valve reaches its end point (e.g., within the housing), the PWM duty cycle may be reduced, which may reduce power consumption and heat generation in the PD system 10. For example, the control unit 100 may instruct the I / O driver (e.g., via a second control signal) to ramp down the PWM signal applied to the coil corresponding to a duty cycle that is 25% or greater (e.g., 50% or greater). When the valve is to be stopped (e.g., closed and / or shut off), the I / O driver may ramp down the PWM to 0% (e.g., from 50%) within 25 to 75 ms (e.g., about 50 ms).

[0128] FIG. 9 is a block diagram illustrating a system and method for reducing noise generated by solenoid valve operation in a medical fluid system using pulse width modulation (“PWM”) in accordance with a non-limiting embodiment of the present disclosure.

[0129] The system may include a control unit 100 of the PD system 10, which may further include a memory 102 and a processor 104, as described above. The system may further include a plurality of input / output (“I / O”) nodes 904 (also referred to as I / O drivers) 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 may include solenoid valves 154, 194 ( FIGS. 2 and 3 ) used by the PD system 10 to control the flow of fresh and spent PD fluid. Accordingly, each valve 510 may include a corresponding housing 514, a respective solenoid coil 512, and a corresponding plunger 516. Each valve 510 may be configured to actuate fluid flow through the tubing of the PD system 10 by applying a voltage to the respective solenoid coil 512 via the respective I / O node 904 to move the corresponding plunger 516 within the corresponding housing 514. Each valve may be configured, via a respective I / O node 904, to close the flow of fluid through the tube by not applying (e.g., reducing) a voltage to a corresponding coil 512 to move a corresponding plunger 516 in the opposite direction of a corresponding housing 514 (e.g., to block the corresponding tube).

[0130] To reduce noise associated with valve actuation (e.g., valve opening) of a given valve, the control unit 100 may be configured to transmit a control signal (e.g., via the processor 104 processing computer-executable instructions stored in the memory 102) to an I / O node associated with the valve (block 902). The control signal may be a digital or analog signal. A control signal, referred to as a first control signal to distinguish it from subsequent control signals described herein, may instruct the I / O node 904 to apply and ramp up a PWM signal (e.g., voltage) to the solenoid coil 512 of the valve 510 (block 906). For example, the I / O node may ramp up the duty cycle of the pulsed application of voltage to the corresponding coil from 0% to 100% in approximately 50 ms. The ramping up of the voltage applied to the solenoid coil 512 moves the plunger 516 of the valve 510 more slowly during actuation (e.g., as opposed to a sudden application of voltage). Thus, the slower movement may reduce the sound generated by the corresponding plunger of the valve 510 (block 908). After the plunger 516 reaches an end position (e.g., within the housing 514) during valve actuation, the control unit 100 may transmit 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 V in The ramp down in block 912 may be useful to conserve power in the PD system 10.

[0131] To reduce noise associated with valve deactivation (e.g., valve closure) for a given valve, the control unit 100 may be configured to transmit 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 ramp down the PWM signal (e.g., voltage) applied to the corresponding coil 512 of the valve 510 (block 914). For example, the ramp down of the PWM 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., approximately 50 ms). The ramp down of the voltage applied to the solenoid coil 512 causes the plunger 516 to move more slowly during deactivation (e.g., as opposed to abrupt removal of voltage). Thus, the slower movement may reduce sound generated by the corresponding plunger of the valve 510 (block 918). In some embodiments, one or more capacitors may be disposed in series between the control unit 100 and the I / O node 904. The ramp-up and / or ramp-down duration of the PWM signal may be based on the capacitance value of each of the one or more capacitors. Additionally or alternatively, one or more resistors may be disposed in series between the control unit 100 and the I / O node 904. The ramp-up and / or ramp-down duration of the PWM signal may be based on the resistance value of each of the one or more resistors.

[0132] (Evaluation of the functionality of solenoid valve actuation) As previously mentioned, a reliable methodology for verifying whether solenoid valves, such as valves 154, 194 (FIGS. 2 and 3), used in PD systems and cyclers (as well as other medical fluid systems and machines) are functionally operating (e.g., opening properly when energized) is desirable and needed. Without such a verification system and method, a dangerous situation could arise. For example, if the machine is operating in one mode (e.g., to open valves 154, 194 to allow fluid flow) and the valves are configured in another mode (e.g., valves 154, 194 are actually closed and no fluid is flowing), the PD system 10 could malfunction and halt therapy. As described herein, the functionality of solenoid valves 154, 194 (e.g., whether the valves are operating properly) can be determined by analyzing the current drawn by the solenoids that operate the valves when activated. A trained classification model can be applied to the current profiles to distinguish between valves 154, 194 whose solenoids are properly energized, resulting in successful actuation, and valves 154, 194 that fail to actuate.

[0133] In some embodiments, the same methodology discussed for ensuring that the valve 154, 194 is operating properly or open can be used to verify whether the solenoid valve is functionally deactivated (e.g., properly closes when de-energized). For example, a current profile of the solenoid operating the valve 154, 194 at the time the valve is commanded to deactivate can be received. A classification model can be trained to distinguish current profiles associated with successful valve de-energization from current profiles associated with unsuccessful valve de-energization. The trained classification model can be applied to the current profile of the solenoid commanded to deactivate to determine whether the solenoid valve 154, 194 is functionally deactivated or closed.

[0134] FIG. 10A is a current profile of a solenoid valve, such as valve 154, 194 (FIGS. 2 and 3), having successful actuation according to an exemplary embodiment of the present disclosure. Additionally, the graph in FIG. 10A plots the current over time for the solenoid coil 164, 204 in the solenoid valve when the solenoid coil is energized during actuation of the solenoid valve 154, 194 (e.g., to open the solenoid valve). The graph shows current measurements taken at frequent intervals (e.g., at a frequency of about 5 kHz). As shown in FIG. 10A, successful actuation of the solenoid valve 154, 194 results in the current first peaking (e.g., at position 1002a) before declining. The initial peak and subsequent decline are due to the plunger 166, 206 of the solenoid valve 154, 194 entering the magnetic field of the solenoid coil 164, 204 as the plunger moves toward the solenoid valve housing. Movement of the plunger 166, 206 through the magnetic field of the solenoid coil 164, 204 generates an opposing voltage that "blocks" the rise of current through the solenoid coil, causing the current to drop after an initial peak 1002a. The plunger 166, 206 hits the end of its movement (e.g., by coming to rest on the solenoid valve housing) at approximately 22 ms, as shown at position 1004a in FIG. 10A. The halt in the plunger 166, 206's movement causes the previous opposing voltage generation to cease and the current to rise again, as shown by rise 1006a in FIG. 10A. Therefore, to verify that the plunger 166, 206 has moved and therefore the solenoid valve 154, 194 has actually opened upon actuation, the current profile should exhibit a "dip" 1004a, for example, at approximately 22 ms. When the plunger 166, 206 is not moving, the current profile may resemble a regular "RC curve" (ie, no dips occur).

[0135] FIG. 10B is a second, different current profile for a solenoid valve, e.g., valve 154, 194 (FIGS. 2 and 3), having successful actuation according to an exemplary embodiment of the present disclosure. Similar to FIG. 10A, the graph in FIG. 10B plots the current over time in the solenoid coil 164, 204 of the solenoid valve 154, 194 when the solenoid coil is energized during actuation of the solenoid valve (e.g., to open the solenoid valve). As previously discussed, successful actuation of the solenoid valve 154, 194 results in the current first reaching a peak (e.g., at position 1002b) before beginning to decline. The initial peak and subsequent decline are due to the plunger 166, 206 of the solenoid valve 154, 194 entering the magnetic field of the solenoid coil 164, 204 as the plunger moves in a direction toward the solenoid valve housing. Movement of the plunger 166, 206 through the magnetic field of the solenoid coil 164, 204 generates an opposing voltage that "blocks" the rise of current through the solenoid coil, causing the current to drop after an initial peak 1002b. Here, the plunger 166, 206 hits the end of its movement (e.g., by coming to rest on the housing of the solenoid valve 154, 194) at approximately 60 ms, as shown at position 1004b in FIG. 10B . The halt in the movement of the plunger 166, 206 causes the previous generation of opposing voltage to cease and the current to rise again, as shown at rise 1006b in FIG. 10B . Differences in the current profiles between the graphs of FIGS. 10A and 10B may be based on the type of sensor used and / or one or more parameters, configurations, and / or characteristics of the sensor used.

[0136] FIG. 10C is a current profile of a solenoid valve, such as valve 154, 194 (FIGS. 2 and 3), having a successful deactivation according to an exemplary embodiment of the present disclosure. The graph in FIG. 10C plots the current over time in the solenoid coil 164, 204 of the solenoid valve 154, 194 when the solenoid coil is de-energized during deactivation of the solenoid valve (e.g., due to closure of the solenoid valve). As shown in FIG. 10C, successful deactivation of the solenoid valve 154, 194 results in the current first reaching a local minimum (e.g., at position 1002c) before beginning to rise. The local minimum and subsequent rise are due to the plunger 166, 206 of the solenoid valve 154, 194 leaving the magnetic field of the solenoid coil 164, 204 as the plunger moves away from the solenoid valve housing. As the plunger 166, 206 moves away from the magnetic field of the solenoid coil 164, 204, the voltage drops, causing the current through the solenoid coil to drop, resulting in a local minimum 1002c before the current rises again. At approximately 90 ms, the plunger 166, 206 hits the end of its travel after exiting the housing and closes the tube, as shown at position 1004c in FIG. 10C. When the plunger 166, 206 stops moving, the current drops again, as shown at drop 1006c in FIG. 10C. Therefore, to verify that the solenoid valve 154, 194 actually closed upon deactivation, the current profile should exhibit a "peak" 1004c, for example, at approximately 90 ms.

[0137] 11 is a flowchart of an example process 1100 for evaluating the functionality of solenoid valve actuation according to an example embodiment of the present disclosure. Process 1100 may be performed by a computing system having one or more processors. Furthermore, the processor and / or computing system may perform process 1100 based on computer-executable instructions stored in memory of the computing system. As used and described for ease of explanation, the computing system may comprise a control unit 100 of the PD system 10, which includes one or more processors 102 and one or more memories 104.

[0138] Process 1100 may begin with the PD system 10 activating one or more valves 154, 194 ( FIGS. 2 and 3 ) and initiating the flow of electrical current (block 1102). For example, during the normal course of operation of the PD system 10, one or more valves 154, 194 may be commanded to be activated to allow fluid flow through tubing associated with the valves. Additionally or alternatively, while the PD system 10 is not providing patient services (e.g., during a pre-treatment or pre-conditioning period of the PD system 10), the control unit 100 may activate (e.g., by sending an electronic signal command) the valves 154, 194 of the PD system 10. However, as described below, activating or commanding the activation of a valve 154, 194 does not necessarily activate the valve to open, for example, if the valve is malfunctioning. As discussed herein, process 1100 discloses one or more embodiments that use a current profile to determine whether the valve 154, 194 is functioning properly.

[0139] Thus, for each valve, the control unit 100 may receive current measurements at a predetermined sampling rate over a predetermined duration (block 1104). It should be understood that the sampling rate needs to be high enough to capture the behavior of the valve 154, 194. For example, as shown in the current profile 1200 of FIG. 12 discussed herein, the sampling frequency may be approximately 100 to 200 Hz. Furthermore, it should be understood that the duration may need to be long enough to capture a significant period; for a valve 154, 194 to open normally, the valve's current profile exhibits a dip (e.g., approximately 22 milliseconds), as discussed above in connection with FIGS. 10A and 10B. Blocks 1106 through 1122 may be performed iteratively for each valve being evaluated for functionality (e.g., to determine whether the valve 154, 194 is actually operating). Additionally or alternatively, blocks 1106 through 1122 may be performed simultaneously for each valve.

[0140] For example, the valve 154, 194 may be selected for actuation evaluation (block 1106). Based on the valve current measurements (received in block 1104), the control unit 100 may identify a rise time of the valve current (block 1108). The rise time may correspond to a generally positive slope of the current measurements over time. For successful valve actuation, the rise time may correspond to a positive slope of the current profile after a dip (e.g., after the plunger has completed travel through the solenoid coil and is within the housing of the solenoid valve). However, since it may not yet be known whether the valve 154, 194 actuated successfully, and a dip in the current profile may not be identifiable, a general slope may be evaluated to identify the rise time of the current based on the overall current measurements from the time the valve is commanded to actuate to the time the rise in current subsides. In some aspects, the rise time may be measured by the duration for which the slope of the curve exceeds at least a predetermined value, whereby the end of the rise time may correspond to when the increase in current measurements subsides. For example, based on the sampling frequency shown in FIG. 12 (e.g., approximately 100-200 Hz), the identified rise time may include 20 current measurements.

[0141] In block 1110, the control unit 100 may determine a maximum current value for normalization of the valve current profile based on the rise time. In some embodiments, determining the maximum current value may involve comparing the received current measurement for the valve 154, 194 selected in 1106 with received current measurements for other valves 154, 194 of the PD device 20. It should be understood that the PD system 10 may be configured to conserve power, if necessary, during valve actuation. For example, the valves 154, 194 of the PD system 10 may be configured not to operate at full current. Thus, the received valve current measurements may each indicate a different maximum current based on the current that each valve 154, 194 may be allocated to use for actuation. Because 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 the received current measurements (in block 1102), for example, by dividing each current measurement by the maximum current value.

[0142] At block 1112, a profile of the current measurements may be generated based on the normalization (e.g., using the calculated maximum current value). In some aspects, the generated profile may be based on time samples corresponding to the rise time identified at block 1108, for example, by truncating irrelevant time samples.

[0143] At block 1114, the control unit 100 may apply a polynomial model to the profile. In some embodiments, applying the polynomial model may include initializing parameters for the polynomial model, for example, by creating initial estimates and / or randomized values ​​for missing variables and coefficients for the optimization process.

[0144] While increasing the sampling rate and / or frequency may facilitate a more effective polynomial model fitting to the current profile, it is contemplated that in some embodiments, fitting or estimating the polynomial model may be performed without the need to increase the sampling for additional sampling. Because the current behavior of the valve 154, 194 over time may be predicted based on the maximum current determination (e.g., from block 1110), one or more data points earlier in time may be added to the current profile for the valve. This addition may adapt the estimated polynomial model to better capture the dynamic behavior of the valve's current profile.

[0145] The polynomial model and its parameters may be optimized in block 1116 (e.g., by a recursive or non-recursive estimation process such as least mean square estimation (“LSME”) using the current profile). In at least one embodiment, a polynomial fit for the current profile for the valve (e.g., generated in block 1108) may be obtained via an LSME process. In an exemplary embodiment in which the current profile includes 20 current measurements (e.g., as shown in FIGS. 12 and 13), a fifth-order polynomial model may be selected. A higher polynomial order places a higher load on the control unit 100, thus resulting in increased processing time and a greater strain on processing power. However, the order may need to be high enough to capture the behavior of the current profile (e.g., the initial peak 1002, dip 1004, and subsequent rise 1006), yet low enough to be manageable by the control unit 100. The same type of balancing operation may be applied to the number of samples taken. There should be enough samples to accurately capture the current profile behavior, but too many samples may overload a processor (e.g., processor 102). Furthermore, higher-order polynomials may have undesirable behavior in the fitting process described herein. Therefore, a polynomial model order may be selected that can well capture the "dip" in the current profile (when the valve operates normally). However, if there is no dip in the valve current profile (e.g., there is a failed opening of the valve), the higher-order terms may be estimated to be close to zero.

[0146] At block 1116, a polynomial model may be optimized to the current profile by an estimation process (e.g., LMSE). In some embodiments, the polynomial model used in LMSE may be expressed as follows:

[0147]

number

[0148] where γN is the observation vector (i.e., the samples of current measurements received in block 1104), and Φ N is the regression matrix, θ is a parameter vector describing the system (e.g., a polynomial model that calculates currents from timestamps), and e represents the error of the polynomial fit to the sampled data. Since the sample interval is known and the number of samples is chosen (e.g., a sampling interval of every 0.001 seconds and every 120 samples), the regression matrix Φ N can be calculated as follows:

[0149]

number

[0150]

number

[0151]

number

[0152] In one embodiment, the parameter vector θ can be expressed using the following equation:

[0153]

number

[0154] where:

number

number

number

number

[0155] At block 1118, the control unit 100 may apply the optimized polynomial model to the trained classification model to determine the valve's actuation state. The classification model may be trained based on a reference dataset of current profiles and / or a polynomial model representing such current profiles labeled with actuation states (e.g., successful actuation or unsuccessful actuation). Process 1400 described in FIG. 14 provides at least one example embodiment for training such a classification model. The trained classification model may include a support vector machine (“SVM”), as described in FIG. 14. Additionally or alternatively, other supervised machine learning models for classifying or distinguishing between different datasets may be utilized.

[0156] The output of applying the optimized polynomial model to the trained classification model may include an actuation state of successful actuation (e.g., the polynomial model fits to a class of polynomial models based on the current profiles of valves with successful opening) or unsuccessful actuation (e.g., the polynomial model fits to a class of polynomial models of the current profiles of valves with unsuccessful opening). In some embodiments, there may be additional options for the output (e.g., no opening, almost successful opening, etc.) depending on the labeled training data used to train the classification model. Thus, an actuation state may be determined, and in block 1120, the control unit 100 may identify whether the valve being evaluated has successful actuation (e.g., block 1120—Yes).

[0157] If the valve is determined to have successful actuation (e.g., based on blocks 1106 through 1120), the control unit 100 may determine whether there are additional valves to evaluate (block 1124). If there are additional valves, blocks 1106 through 1120 may be repeated for those additional valves to evaluate their current profiles for successful actuation. If, based on the evaluation of the current profiles, it is determined that the valve 154, 194 is not actuated (e.g., block 1120—No), the control unit 100 may alert the operator that the valve is malfunctioning. For example, the PD system 10 may generate a warning, caution, and / or danger symbol (e.g., via an indicator display) or may generate an audio or visual cue. After each valve 154, 194 has been evaluated and / or any malfunctions have been reported, the control unit 100 may terminate evaluation of the valve's actuation functionality (block 1126).

[0158] In some embodiments, alternatives to polynomial models may be used to represent and / or fit the current profile. For example,

number

[0159] In some embodiments, variations of one or more steps of process 1100 may be used to evaluate the functionality of a solenoid valve's deactivation, e.g., closure. 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 being evaluated, a profile of current measurements may be generated using the process described above (blocks 1104 through 1112). A polynomial model may be applied to the current profile and optimized (blocks 1114 and 1116). The optimized polynomial model, which estimates the current profile of a given solenoid valve when commanded to deactivate, may be applied to a trained classification model (e.g., a support vector machine) to detect whether there is an actual or failed deactivation, e.g., closure, of the solenoid valve (block 1118). The classification model trained to detect stalling may differ from the classification model trained to detect actuation because the former may rely on reference training data of two sets of current profiles associated with (i) successful and (ii) unsuccessful stalling of the valve, respectively.

[0160] FIG. 12 illustrates a sampled, normalized current profile 100 of a solenoid valve 154, 194 with successful actuation according to an exemplary embodiment of the present disclosure. For example, current profile 1200 may be generated by control unit 100 in block 1112 of process 1100 (e.g., after normalizing each current measurement based on the maximum current). The stepped nature of current profile 1200 (e.g., as opposed to the current profiles shown in FIGS. 10A and 10B ) may result from a lower sampling frequency, which may facilitate more efficient processing for assessing the functionality of valve actuation. The improved efficiency resulting from a lower sampling rate may enable faster and more effective alerts to malfunctioning valves within PD system 10, thus improving patient care. As discussed above in connection with FIGS. 10A and 10B , current profile 1200 may correspond to a valve 154, 194 with successful actuation due to a signature “dip” in the current (e.g., approximately 22 milliseconds). However, in current profiles with lower sampling rates (e.g., current profile 1200), it may be difficult to identify the "dip." Therefore, PD system 10 (via its control unit 100) may rely on process 1100 to determine that current profile 1200 corresponds to a valve with successful actuation.

[0161] In contrast, FIG. 13 is a sampled, normalized current profile 1300 of a solenoid valve 154, 194 having failed actuation according to an exemplary embodiment of the present disclosure. Similar to the current profile 1200 of FIG. 12, the current profile 1300 may be generated by the control unit 100 in block 1112 of the process 1100 (e.g., after normalizing each current measurement based on the maximum current). The stepped nature of the current profile 1300 (e.g., as opposed to the current profiles shown in FIGS. 10A and 10B) may result from a lower sampling frequency, which may make it more difficult to identify the signature “dip” or lack thereof to assess whether the current profile 1300 indicates successful or failed valve opening. However, as previously discussed, the process 1100 may be used to determine that the current profile 1300 corresponds to a valve having failed actuation.

[0162] FIG. 14 is a flowchart of an example process 1400 for training a classification model (e.g., an SVM) for evaluating the function of solenoid valve actuation according to an example embodiment of the present disclosure. As previously described, process 1400 illustrates an example embodiment for training a classification model used in block 1118 of process 1100 (e.g., to provide an optimized polynomial model). Process 1400 may be performed by a computing system (e.g., control unit 100 of PD system 10) having one or more processors (e.g., processor 102). For example, processor 102 may perform process 1400 based on computer-executable instructions stored in memory 104. In some embodiments, process 1400 may occur on a remote computing system (e.g., a remote server or a big data analysis lab) different from control unit 100 of PD system 10, although process 1400 is described as being performed by control unit 100 of PD system 10 for ease of explanation.

[0163] The process 1400 may begin with the control unit 100 receiving a reference data set of a plurality of current profiles corresponding to a valve 154, 194 having successful actuation (block 1402). This reference data set may be referred to as a first reference data set to distinguish it from a reference data set received in block 1406 of another plurality of current profiles corresponding to a valve having unsuccessful actuation (referred to as a second reference data set).

[0164] The first reference data set may be labeled as having a successful actuation 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 actuation.

[0165] At block 1406, the control unit 100 may receive a second reference data set of multiple reference current profiles corresponding to valves 154, 194 having failed actuation (e.g., the valve failed to open during the time period corresponding to the current profile). The second reference data set may be labeled as having the result of failed actuation (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 actuation.

[0166] In 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 and unsuccessful actuations. For example, each data set, whether corresponding to the first or second reference data set, may be based on or fitted to (e.g., using the LSME method described in block 1116 of process 1100) a polynomial model of a predetermined degree (e.g., 5 degrees). In the case of an n-th degree polynomial model, the coefficients of each degree up to the nth degree may be used as parameters for the classification model (e.g., SVM) to plot and / or arrange individual data points (i.e., observations).

[0167] At blocks 1412 and 1414, different decision boundaries may be tested to see how effectively they separate data belonging to a first reference data set from a second reference data set (block 1412) until convergence (block 1414) is reached. In some embodiments, convergence may indicate that the tested decision boundary provides the largest margin between data points belonging to the first reference data set and data points belonging to the second reference data set. Furthermore, the decision boundary may indicate which side a given polynomial model may fall on (e.g., the side of the first reference data set corresponding to a successful operation or the side of the second reference data set corresponding to a failed operation) based on the coefficients of each parameter of the polynomial model.

[0168] The trained classification model, e.g., a trained support vector machine with parameters for the decision boundary, may be stored (e.g., in memory 104 of control unit 100) in block 1416. The trained support vector machine can then be used to apply the optimized polynomial model from process 1100 and determine whether the current profile belongs to the side of successful actuation (e.g., the same side as the first reference data set) or the side of unsuccessful actuation (e.g., the same side as the second reference data set).

[0169] A trained classification model, such as a support vector machine, may include a supervised learning model that analyzes training data (e.g., multiple current profiles used as references (referred to herein as reference current profiles) and knowledge of whether each reference current profile corresponds to successful or unsuccessful actuation) and automatically learns (e.g., via an iterative error minimization process) relationships between input data (e.g., various parameters of any given current profile) and two or more separate outcomes (e.g., whether the current profile corresponds to successful or unsuccessful actuation). The learned relationships may then be applied to test data having unknown outcomes (e.g., current profiles of valves whose valve actuation state is unknown) to determine the outcome (e.g., whether the valve actually actuated successfully). An SVM may be an example of a classification model in which the learned relationships are decision boundaries (e.g., to separate current profiles of valves with successful actuation from current profiles of valves with unsuccessful actuation).

[0170] In some embodiments, variations of one or more steps of process 1400 may be used to train a classification model for evaluating the functionality of a solenoid valve's shutdown (e.g., whether the valve is actually closed). For example, a first reference data set may include multiple reference current profiles indicative of successful shutdown or valve closure (block 1402), and a second reference data set may include multiple reference current profiles indicative of unsuccessful shutdown or valve closure (block 1406). The first and second reference data sets may be labeled as successful shutdowns (block 1404) and unsuccessful shutdowns (block 1408), respectively. The labeled data sets may be used in a training process (blocks 1410 through 1414), and the resulting trained support vector machine may be stored for use in identifying whether a given valve has a successful shutdown (block 1416).

[0171] 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, it is intended that such changes and modifications be covered by the appended claims. For example, while MOSFETs and NPN transistors have been described as transistors used to assist in noise reduction during solenoid valve actuation and deactivation, other transistors could similarly be used to slow the solenoid valve's plunger to similarly reduce noise. As another example, a support vector machine was used to classify the current profile of a valve that actuated successfully from the current profile of a valve that actuated unsuccessfully, although other machine learning models could be utilized for this classification. As a further example, as discussed herein, the systems and methods of the present disclosure can be used to evaluate both valve actuation (e.g., whether the valve is actually open) and valve deactivation (e.g., whether the valve is actually closed). For example, an optimized polynomial model of the current profile of a solenoid valve when commanded to deactivate can be applied to a trained classification model to determine whether the solenoid valve is actually closed. In yet another example, any of the solenoid valves described herein may be, but are not necessarily, solenoid pinch valves. In still a further example, although different valve embodiments are discussed primarily in connection with peritoneal dialysis ("PD"), valve embodiments may be used with other medical fluid systems and associated machines, such as those for hemodialysis ("HD"), hemofiltration ("HF"), hemodiafiltration ("HDF"), and continuous renal replacement therapy ("CRRT").

Claims

1. 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; Multiple valves and Equipped with Each valve comprises a housing, a coil, and a plunger; each valve configured to energize the corresponding coil via an associated NPN transistor to move the corresponding plunger within the corresponding housing, thereby allowing flow of medical fluid through the tube; The control unit comprises at least one processor and at least one memory, the at least one memory storing instructions that, when executed by the at least one processor, causing the at least one processor to transmit a control signal to one of the NPN transistors configured to cause a ramp-up of an input current to the NPN transistor; the ramping up of the input current to the NPN transistor causes a corresponding valve to ramp up the voltage applied to the corresponding coil; A medical fluid system wherein the ramp-up of the voltage applied to the corresponding coil causes the corresponding plunger to move in a manner in which sound produced by the corresponding plunger is reduced compared to operation without the NPN transistor.

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

3. 2. The medical fluid system of claim 1, wherein each valve is configured to close the flow of medical fluid through the tubing by not applying the voltage to the corresponding coil, as caused by the corresponding NPN transistor, such that the corresponding plunger moves in the opposite direction and occludes the corresponding tubing.

4. The instructions, when executed by the at least one processor, further cause the at least one processor to turn off the low control signal, the turning off causing the input current to the NPN transistor to ramp down; the ramping down of the input current to the NPN transistor causes the corresponding valve to ramp down the voltage applied to the corresponding coil; 4. The medical fluid system of claim 3, wherein the ramping down of the voltage applied to the corresponding coil causes the corresponding plunger to move in an opposite direction and in a manner in which sound produced by the corresponding plunger is reduced compared to operation without the NPN transistor.

5. 1. 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; Multiple valves and Equipped with Each valve comprises a housing, a coil, and a plunger; each valve configured to energize the corresponding coil via an associated MOSFET to move the corresponding plunger within the corresponding housing, thereby allowing flow of medical fluid through the tube; The control unit comprises at least one processor and at least one memory, the at least one memory storing instructions that, when executed by the at least one processor, causing the at least one processor to transmit a high-level digital control signal to one of the MOSFETs; the MOSFETs, in response to the high digital control signals, cause the corresponding valves to ramp up the voltage applied to the corresponding coils until the voltage reaches a predetermined input voltage Vin; A medical fluid system, wherein the ramping up of the voltage applied to the corresponding coil causes the corresponding plunger to move in a manner such that sound produced by the corresponding plunger is reduced compared to operation without the MOSFET.

6. 6. The medical fluid system of claim 5, wherein each valve is configured to close the flow of medical fluid through the tubing by not applying the voltage to the corresponding coil via the corresponding MOSFET such that the corresponding plunger moves in the opposite direction and occludes the corresponding tubing.

7. The instructions, when executed by the at least one processor, further causing the at least one processor to transmit low-digital control signals to the MOSFETs of the plurality of MOSFETs; the MOSFET responding 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; 7. The medical fluid system of claim 6, wherein the ramping down of the voltage applied to the corresponding coil causes the corresponding plunger to move in an opposite direction and in a manner in which sound produced by the corresponding plunger is reduced compared to operation without the MOSFET.

8. and at least one resistor disposed in series between the control unit and the MOSFET. a duration of the ramp-up of the voltage applied to the corresponding coil based on at least one resistance value of the corresponding at least one resistor; The medical fluid system of claim 7 , wherein a 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. further comprising at least one capacitor disposed in series between the control unit and the MOSFET; the duration of the ramp-up of the voltage applied to the corresponding coil is further based on a capacitance value of the corresponding at least one capacitor; The medical fluid system of claim 8 , 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. 6. The medical fluid system of claim 5, further comprising an initial ramp offset circuit comprising a feedback resistor.

11. The instructions, when executed, 11. The medical fluid system of claim 10, further comprising: applying, via the initial ramp offset circuit, an offset voltage that is set lower than the voltage applied to the corresponding coil when ramping up the input current to the MOSFET.

12. 1. A medical fluid system, comprising: a control unit; a plurality of input / output ("I / O") nodes configured to control a plurality of valves via pulse width modulated ("PWM") signals in response to control signals received from the control unit; Multiple valves and Equipped with Each valve comprises a housing, a coil, and a plunger; each valve configured to energize the corresponding coil via an associated I / O node to move the corresponding plunger within the corresponding housing, thereby enabling flow of medical fluid through the tube; The control unit comprises at least one processor and at least one memory, the at least one memory storing instructions that, when executed by the at least one processor, causing the at least one I / O node to transmit a control signal to an I / O node of the plurality of I / O nodes, the control signal causing the I / O node to apply a PWM signal to the corresponding coil to ramp up; A medical fluid system, wherein the ramping up of the PWM signal causes the corresponding plunger to move in a manner such that sound produced by the corresponding plunger is reduced compared to operation without the PWM signal.

13. 13. The medical fluid system of claim 12, wherein ramping up the PWM signal includes ramping up the duty cycle of pulsing the voltage to the corresponding coil from 0% to 100% over 50 ms.

14. The instructions, when executed, 13. The medical fluid system of claim 12, further comprising: transmitting a second control signal to the I / O node after the plunger reaches an end position, 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. 15. The medical fluid system of claim 14, wherein the second control signal causes the I / O node to ramp down the PWM signal to the corresponding coil to at least a 50% duty cycle.

16. 15. The medical fluid system of claim 14, wherein each valve is configured to close the flow of medical fluid through the tubing by not applying the voltage to the corresponding coil via the corresponding I / O node such that the corresponding plunger moves in the opposite direction and occludes the corresponding tubing.

17. The instructions, when executed by the at least one processor, further causing the at least one processor to transmit 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 0% duty cycle; 17. The medical fluid system of claim 16, wherein the ramping down of the PWM signal to the corresponding coil causes the corresponding plunger to move in an opposite direction and in a manner in which sound produced by the corresponding plunger is reduced compared to operation without the PWM signal.

18. 18. The medical fluid system of claim 17, wherein the ramping down of the PWM signal to the corresponding coil to the duty cycle of 0% occurs between 25 and 75 ms.

19. further comprising at least one resistor disposed in series between the control unit and the I / O node; a duration of the ramp-up of the PWM signal based on a resistance value of the corresponding at least one resistor; 18. The medical fluid system of claim 17, wherein a duration of the ramp down of the PWM signal is based on the resistance value of the corresponding at least one resistor.

20. further comprising at least one capacitor disposed in series between the control unit and the I / O node; the ramp-up duration of the PWM signal is further based on a capacitance value of the corresponding at least one capacitor; 18. The medical fluid system of claim 17, 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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