Magnetic coupling and detection mechanism for a pump device - Patents.com

Abstract

The bi-functional magnetic mechanism exerts a magnetic attraction force to magnetically couple the disposable and reusable parts of the pump device, and at the same time, the bi-functional magnetic mechanism detects the engagement state between the two parts of the pump device using the same magnetic field. The bi-functional magnetic mechanism includes a permanent magnet that generates a magnetic field that nulls the net magnetic field at the sensor, an asymmetric metal plate (AMP) that magnetically disrupts (deflects, redirects) the magnetic field at the sensor, and a magnetic field sensor that senses the magnetic disruption. The magnet and sensor are incorporated into the reusable part of the pump device such that the magnetic field sensor is circumferentially surrounded by the magnet. The AMP is incorporated into the disposable part such that the AMP is in a facing relationship to the sensor (i.e., adjacent to the sensor) when the disposable and reusable parts are engaged.

Description

[Technical field] 【0001】 The present invention relates generally to a system and method for coupling a disposable part (DP) (e.g. a liquid drug container / reservoir) of a drug delivery device (pump device) to a reusable part (RP) of said pump device, and more particularly to a magnetic coupling mechanism for magnetically detachably coupling (removably coupling / engaging) the DP of a drug delivery device to a RP, and a magnetic field based detection method for detecting the engagement (coupling / coupling) and disengagement (disengagement) of the DP and RP of said drug delivery device, and optionally the direction of engagement. [Background technology] 【0002】 Liquid drug delivery systems include two-part systems that include a RP, which typically includes, among other things, an electric motor and a gear system driven by the electric motor, and a DP, which typically includes a liquid drug reservoir and a gear-driven plunger rod that expels the liquid drug out of the reservoir. NeuroDerm Limited, an Israel-based company, for example, has developed a proprietary miniature two-part wearable infusion drug delivery device for delivering liquid drugs subcutaneously to Parkinson's Disease (PD) patients. 【0003】 The ability to detect proper engagement of the DP and RP by the sensor system and the pump device controller has advantages, for example, in terms of safe operation of a liquid drug delivery system, ensuring accurate drug dosing and avoiding various mechanical problems that may arise from mechanical wear and damage (which may change mechanical tolerances). For example, engagement of the DP of the pump device with the RP of the pump device is a prerequisite for safe operation of the pump device. 【0004】 Some pump devices use a magnetic field source and a magnetic field sensor to sense the proper engagement of the DP and RP of the pump device. In these devices, typically the DP includes a magnet as a magnetic field source, and the RP includes a magnetic field sensor. Using this type of "magnet-sensor" configuration, the magnetic field sensed by the magnetic field sensor is maximum when the DP and RP are engaged, and conversely, when the DP and RP are pulled away from each other, the magnetic field sensed by the magnetic field sensor is minimum. Thus, the engagement state of the DP and RP is determined accordingly (e.g., by a controller). Incorporating magnets into the DP is wasteful, since it requires a magnet in each DP, plus the need to magnetize all magnets exactly the same to ensure that all pump devices operate the same. 【0005】 Typically, the DP of the pump device including the magnet and the RP of the pump device including the magnetic field sensor are coupled using a mechanical coupling device or connector, such as a snap-fit ​​mechanism (e.g., a cantilever snap-fit), a threaded interlocking part, or a bayonet connector. It would be beneficial to have a pump device that allows a magnet to be used to releasably couple the DP of the pump device to the RP while simultaneously sensing engagement and disengagement of the DP and RP of the pump device. Additionally, it would be beneficial to have a pump device that improves ease of use for patients with movement disorders, especially those who are unable to operate mechanisms that require precise and accurate movements or physical force, or both, as is often the case with PD patients. Summary of the Invention 【0006】 The bifunctional magnetic mechanism generates a magnetic attraction force to magnetically engage the disposable and reusable parts of the pump device, and at the same time, the bifunctional magnetic mechanism detects the engagement state between the two parts of the pump device using the same magnetic field. The bifunctional magnetic mechanism includes a permanent magnet that generates a magnetic field that nulls the net magnetic field at the sensor, an asymmetric metal plate (AMP) that magnetically disrupts (deflects, redirects) the magnetic field at the sensor, and a magnetic field sensor that senses the electromagnetic disruption / deflection. The magnet and sensor are integrated into the RP of the pump device such that the magnetic field sensor is circumferentially surrounded by the magnet. The AMP is integrated into the DP such that the AMP faces the sensor (i.e., adjacent to the sensor in a functionally optimized state) when the DP and RP are engaged. The design (geometrical relative positions) of these two parts (AMP and magnet / sensor, including other supporting parts) ensures that the AMP is most appropriately centered in front of the magnet / sensor to ensure optimal operation of the mechanism disclosed herein. 【0007】 A pump device for delivering a flowable medicine to a user includes a RP and a DP for engaging with the RP. The RP includes, among other things, a magnetic field sensor having a magnetic field sensing area, a magnet circumferentially surrounding the magnetic field sensor and magnetizing it to generate one or more magnetic fields in a direction that makes the net magnetic field sensed by the magnetic field sensor zero, and a controller for reading an output value of the magnetic field sensor. The DP is magnetically engageable with the RP and includes a metal plate magnetically attractable to the magnet to magnetically engage the DP with the RP, during engagement the metal plate magnetically deflects one or more of the one or more magnetic fields at the magnetic field sensing area such that the net magnetic field sensed by the magnetic field sensor is greater than zero. The controller is configured to determine an engagement state between the DP and the RP from an output value (Sa) of the magnetic field sensor corresponding to the sensed net magnetic field. 【0008】 The magnetic field sensing area, the magnet, and the metal plate each form a plane that is coincident with or parallel to the XZ plane of a Cartesian coordinate system and perpendicular to the Y axis of the Cartesian coordinate system. The magnet includes a central aperture, and the magnetic field sensor is centered in the magnet aperture at a point that coincides with the origin of the Cartesian coordinate system. The metal plate is asymmetric with respect to an asymmetric axis that coincides with the Z axis, and the asymmetric axis divides the metal plate into a main section and an auxiliary section. 【0009】 The main section of the asymmetric metal plate (AMP) is configured to induce a magnetic attraction between the main section and the magnet when the DP is in proximity to the RP, and is also configured to simultaneously deflect one or more of the one or more magnetic fields at or near a sensing area of ​​the sensor. The auxiliary section of the AMP is configured to induce a magnetic attraction between the auxiliary section and the magnet when the DP is in proximity to the RP. The metal plate deflects one or more of the one or more magnetic fields non-uniformly, making the deflection detectable by the controller. The metal plate may be configured to prevent the magnetic field sensor from reaching saturation magnetization when the DP is engaged with the RP, such that the controller can distinguish between an engaged state of the DP and the RP and a fault state in which the magnetic field sensor reaches saturation magnetization. 【0010】 The DP includes one drug reservoir, and the controller can compare the output value (Sa) of the magnetic field sensor with a threshold value (Sth) to determine the engagement state of the DP and the RP. The controller can check the value of Sa once every t1 seconds when the disposable and reusable parts of the pump device are engaged or when the pump device is actually delivering drug to the patient, and can check the value of Sa once every t2 seconds (t2>t1) when the disposable and reusable parts of the pump device are disengaged or when the pump device is not delivering drug to the patient. The value of t1 is, for example, 0.01 seconds, 0.5 seconds, 1.0 seconds, etc., and the value of t2 is, for example, 3.0 seconds, 5.0 seconds, 10.0 seconds, etc. 【0011】 The DP can include two drug reservoirs, and the controller compares the output value (Sa) of the magnetic field sensor with a null value (Snull) of the magnetic field sensor to determine whether the engagement of the DP and the RP is in a first engagement direction (SIDE-B) or a second engagement direction (SIDE-A). The controller compares the output value (Sa) of the magnetic field sensor with a first threshold value (Sth1) to determine that the engagement of the DP is in the first engagement direction (SIDE-B) and compares the output value (Sa) of the magnetic field sensor with a second threshold value (Sth2) to determine that the engagement of the DP is in the second engagement direction (SIDE-A), where Sth1>Snull>Sth2. The first engagement direction (SIDE-B) of the DP and the second engagement direction (SIDE-A) of the DP can be determined by (thanks to) the asymmetric nature of the metal plate with respect to an asymmetric axis coinciding with the Z-axis. The controller may output audible and / or visual indications to a user (eg, a patient) of the pump device as to the accuracy of the engagement and / or engagement direction between the DP and RP. 【0012】 The magnet may be a permanent magnet configured as a diametrically magnetized dipole magnet configured to generate a magnetic field parallel to the magnetic field sensing area such that the net magnetic field sensed by the magnetic field sensor is zero or close to zero. When the DP is engaged with the RP, the net magnetic field sensed by the magnetic field sensor is greater than zero due to the magnetic field deflection that the metal plate causes in the magnetic field sensing area. 【0013】 The magnet may be a permanent magnet configured as a multi-pole magnet. The multi-pole magnet may include a number "n" (n=1, 2, 3, ...) of conjugated pole (N / S) pairs and may be magnetized diametrically or axially or both diametrically and axially. The multi-pole magnet is configured to generate magnetic fields in opposite directions in the magnetic field sensing area such that opposing magnetic fields cancel each other out in the magnetic field sensing area, such that the net magnetic field sensed by the magnetic field sensor is zero or close to zero. The multi-pole magnet may be a four-pole magnet. The four-pole magnet may include a first conjugated pole (N / S) pair axially magnetized in a first direction and a second conjugated pole (S / N) pair axially magnetized in a second direction opposite the first direction. When the DP is engaged with the RP, the magnetic field sensed by the magnetic field sensor is greater than zero due to the metal plate deflecting the magnetic field in the magnetic field sensing area. 【0014】 In some embodiments, the main and auxiliary sections of the AMP are separate, unbonded sections. In other embodiments, the main and auxiliary sections of the AMP form a single monolithic body. 【0015】 In some embodiments, the main section of the asymmetric metal plate (AMP) includes a main tab that extends toward the auxiliary section of the AMP on an inner side of the AMP. In some embodiments, the auxiliary section of the AMP also includes a tab (auxiliary tab) that extends toward the main tab on an inner side of the AMP. The main tab extends further inward than the auxiliary tab and has a larger surface area than the auxiliary tab. 【0016】 The main section of the AMP is configured to overlap the magnetic field sensing area when the DP and RP are engaged, with the overlap ratio being P[%]. The value of P[%] is a trade-off between the magnetic attraction force induced between the magnet and the AMP and the magnetic field deflection induced by the AMP in the magnetic field of the magnetic field sensing area. The value of P[%] can be selected such that the magnetic field sensor does not reach saturation magnetization when the DP and RP are engaged, so that the controller can distinguish between an engaged state and a fault state that causes the magnetic field sensor to reach saturation magnetization. In some embodiments, the value of P is 50%±10%. The design of the AMP is a trade-off between the magnetic attraction force induced between the magnet and the asymmetric metal plate and the magnetic field deflection induced by the asymmetric metal plate in the magnetic field of the magnetic field sensing area. [Brief description of the drawings] 【0017】 Various embodiments and aspects are illustrated in the accompanying drawings, the present invention being not limited thereto. It will be readily understood that for simplicity and clarity of illustration, the components illustrated in the following drawings have not necessarily been drawn to scale. Further, where considered appropriate, the same reference numerals have been used in the various drawings to indicate the same or similar components, etc. The following drawings are attached: 【0018】 [Figure 1] 1 illustrates a schematic cross-section of a magnet-metal plate-sensor (MMS) setup according to one embodiment. 【0019】 [Figure 2A] 2A shows a schematic diagram of a diametrically magnetized dipole circular flat magnet generating a magnetic field in a direction parallel to the plane of the magnetic field sensor (the XZ plane in FIG. 2A) according to one embodiment. 【0020】 [Figure 2B] 2B shows a schematic diagram of a diametrically magnetized dipole circular magnet that generates a magnetic field similar to that shown in FIG. 2A. 【0021】 [Figure 3A] 1 shows a cross section of an axially magnetized dipole circular magnet with a typical magnetic field. 【0022】 [Figure 3B] 1 shows a cross section of a magnet configuration, or layout, that includes two axially magnetized magnets that generate opposing magnetic fields that cancel each other's effects in a magnetic field sensor. 【0023】 [Figure 4A] 3C shows an axially magnetized four-pole magnet that generates two magnetic fields similar to those of FIG. 3B, according to one embodiment. 【0024】 [Figure 4B] FIG. 4B shows a cross section of an axially magnetized four-pole magnet. 【0025】 [Figure 5A-5C] 1 illustrates a metal plate according to one embodiment. 【0026】 [Figure 6A-6B] 4 shows a metal plate according to another embodiment. 【0027】 [Figure 7A-7B] 6A-6B according to one embodiment. 【0028】 [Figure 8] 7A-7B according to one embodiment. 【0029】 [Figure 9] 13 shows various types of metal plates according to further embodiments. 【0030】 [Figure 10A-10C] 13 illustrates the installation of a metal plate on the DP of the pump device according to one embodiment. 【0031】 [Figure 11] 13 shows the installation of a metal plate on the DP of the pump device according to another embodiment. 【0032】 [Figure 12A-12B] 13 shows the installation of a metal plate on the DP of the pump device according to another embodiment. 【0033】 [Figure 13A-13B] 1 illustrates a pump device according to one embodiment. 【0034】 [Figure 14] 1 illustrates a magnet-sensor combination in which a magnetic field sensor is circumferentially surrounded by a magnet, according to one embodiment. 【0035】 [Figure 15A-15B] 1A and 1B show partial longitudinal and width cross sections, respectively, of an engaged pump device DP and RP, according to one embodiment. 【0036】 [Figure 16A-16B] 1 shows an example of an overlap of a magnetic field sensor and an asymmetric metal plate (A,MP) according to one embodiment. 【0037】 [Figure 17] 4 illustrates an example output response of a linear Hall effect sensor. 【0038】 [Figure 18A-18B] FIG. 2 compares saturation and desaturation magnetization curves according to one embodiment. 【0039】 [Figure 19] FIG. 10 compares sensor output response curves of two different AMP designs, according to one embodiment. 【0040】 [Figure 20A-20B] 1 illustrates calibration of an engagement distance according to one embodiment. 【0041】 [Figure 21] 13 illustrates a method for determining engagement of the DP and RP of a pump device, according to one embodiment. 【0042】 [Figure 22] 4 illustrates a method of controlling operation of a pump device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 【0043】 In the following description, various embodiments of the present invention are described in detail, but the following description is not intended to limit the scope of the claims, but rather to provide an illustrative description of the various principles of the present invention and various ways of implementing them. 【0044】 The bi-functional magnetic mechanism described below is designed to generate a magnetic attraction force to couple the DP of the pump device with the RP of the pump device and simultaneously (at the same time) detect the engagement state between the two parts of the pump device (DP and RP) using the same magnetic field. The bi-functional magnetic mechanism includes three main parts. The three main parts include (1) a permanent magnet configured (in terms of the number of conjugate pole pairs and magnetization) to generate a combined magnetic field from one or more magnetic fields oriented in a desired direction, (2) an asymmetric metal plate (AMP) configured to disturb the combined magnetic field generated by the magnet, and (3) a magnetic field sensor to sense the level of disturbance in the combined magnetic field. The magnet and the magnetic field sensor are incorporated in the RP of the pump device such that the magnetic field sensor is circumferentially surrounded by the magnet. Meanwhile, the AMP is incorporated in the DP of the pump device such that the AMP is in a facing relationship to the magnetic field sensor (i.e., adjacent to the sensor) when the DP and RP of the pump device are engaged. Disrupting a magnetic field with an AMP, acting as a magnetic field shunt, means deflecting (redirecting) some of the magnetic field lines from the "natural" or original path of the magnetic field. 【0045】 The AMP is designed to simultaneously perform two types of magnetic interactions with the magnetic field generated by the magnet: (1) the AMP can be magnetically attracted to the magnet, so that it can magnetically couple the DP and RP of the pump device; and (2) the AMP is also designed to disturb (e.g., change or redirect) the magnetic field generated by the magnet, so that the disturbed (changed or redirected) magnetic field can be detected by the magnetic field sensor. The key point when the magnetic field sensor senses the magnetic field is that when the two parts (e.g., the DP and RP of the pump device) that are intended to be coupled are disengaged (i.e., there is a distance between them), the net magnetic field sensed by the magnetic field sensor is zero or close to zero. Therefore, when the net magnetic field sensed by the magnetic field sensor is zero or close to zero, the controller can determine that the DP and RP of the pump device are not engaged by reading the output of the sensor. In contrast, when the DP and RP of the pump device are engaged, any magnetic field disturbance caused by the AMP at or near the magnetic field sensor increases the net magnetic field sensed by the magnetic field sensor, thereby facilitating detection of engagement and disengagement of the two parts (DP and RP) of the pump device. 【0046】 When the DP and RP are disengaged, the net magnetic field sensed by the sensor is nullified (or minimized) by one or more magnetic fields generated by magnets in a specific direction relative to the sensor sensing surface (sensing area) of the magnetic field sensor. Generating a magnetic field in a required direction by magnets can be achieved by redirecting the magnetic field lines by manipulating the magnetization scheme of the magnet. Sintered Neodymium-Iron-Boron (NdFeB) magnets can be magnetized with multiple poles to suit your needs; that is, for example, multiple "N" (north) and "S" (south) poles can be formed in one plane after magnetization. 【0047】 Use of magnetic "shields" to disrupt (deflect, redirect) magnetic fields A magnetic shield generally means surrounding an object (e.g., a magnetic field sensor) with a magnetically conductive material that is better able to "conduct" magnetic flux than the material surrounding the object. With a magnetically conductive material, the magnetic field lines tend to "flow" (i.e., redirect) along this material, thus avoiding objects within it. With a magnetic shield, the magnetic field lines follow a different route to reach the opposite pole. The magnetic field lines follow the path of least magnetic resistance, which is characterized by having a relatively high magnetic permeability μ (e.g. μ>1.0, whereas the magnetic permeability of air μ=1.0). Thus, when a material with high magnetic permeability is near a magnet, the magnetic field lines will take the path of least magnetic resistance (through the high magnetic permeability material) and will have less magnetic strength in the surrounding air ("magnetic permeability" is a scalar quantity that quantifies a material's resistance to a magnetic field, or the degree to which a magnetic field can penetrate a material). A material with high magnetic permeability has a high magnetic susceptibility to an applied magnetic field and is easily magnetized. 【0048】 As described herein (e.g., in connection with Figures 5A-5C, 6A-6B, 7A-7B, 8, and 9), the metal plates are designed asymmetrically with respect to an asymmetric axis coinciding with the Z-axis in the figures, in order to disrupt the magnetic field (e.g., deflect the magnetic field lines) so that the net magnetic field sensed by the magnetic field sensor is not zero when the DP and RP of the pump device are engaged. In a sense, the AMP acts as a shielding means, which means that it unbalances the zero net magnetic field at the magnetic field sensor by deflecting or redirecting at least some of the magnetic field lines in the space around the magnetic field sensor. The change in the magnetic field line direction causes an increase in the net magnetic field. 【0049】 1 illustrates a schematic cross-sectional view of a magnet-metal plate-sensor (MMS) setup 100 according to one embodiment. The MMS 100 includes a magnet 110 (e.g., a permanent magnet), a magnetic field sensor 120, a circuit board 122 for powering the magnetic field sensor 120 and converting an analog output signal (e.g., an output voltage) of the magnetic field sensor 120 into a corresponding digital signal, and an asymmetric metal plate (AMP) 130. The magnet 110 is generally flat and coincident with a plane 112. The magnetic field sensor 120 has a magnetic field sensing area / plane 124 that is parallel or generally parallel to the plane 112. 【0050】 The magnet 110 circumferentially surrounds the magnetic field sensor 120. When the AMP 130 and the magnetic field sensor 120 are separated from each other, the magnet 110 is magnetized to generate one or more magnetic fields in specific directions such that the net magnetic field sensed by the magnetic field sensor 120 is zero. 【0051】 The asymmetric metal plate (AMP) 130 is configured to be magnetically attracted to the magnet 110 when the AMP 130 and the magnet 110 are in close proximity to one another, and further configured to disrupt (e.g., deflect) one or more magnetic fields of the magnetic field sensing area 124 when the AMP 130 is in close proximity to the magnetic field sensing area 124 (e.g., at or near the detection distance 140 from the magnetic field sensing area 124), thereby increasing the net magnetic field sensed by the magnetic field sensor 120. 【0052】 2A shows a schematic of a diametrically magnetized, dipole, circular, flat magnet 210 (e.g., permanent magnet) generating a magnetic field 220 in a direction parallel to the sensing surface of the magnetic field sensor 230 (plane XZ in FIG. 2A ), according to one embodiment. The magnet 210 has an axis 240 that coincides with the Y-axis. As shown in FIG. 2A , the magnetic field sensor 230, which is a flat sensor and has a magnetic field sensing area 232, is slightly (e.g., a few millimeters) “sunk” (recessed relative to the surface 212 of the magnet 210) at the center of the magnet 210 and is circumferentially surrounded by the magnet. 【0053】 The dipole magnet 210 is a ring-shaped magnet that includes a north (N) pole and a south (S) pole opposite the north pole. Using this MMS layout / configuration, the direction of the magnetic field 220, when unobstructed, is parallel to the sensor sensing area / plane 232 of the magnetic field sensor 230, meaning that the angle between the magnetic field sensing area of ​​the sensor and the magnetic field lines is zero degrees. Thus, the net magnetic field sensed by the magnetic field sensor 230 is zero. However, when an AMP (e.g., examples of AMPs are shown in Figures 5A-5C, 6A-6B, 7A-7B, 8, 9, 10B-10C, and 12A-12B) is brought close enough to the magnetic field sensing area 232 of the sensor 230, the magnetic field lines are obstructed (redirected) such that the angle between the magnetic field sensing area 232 of the sensor and at least some of the redirected magnetic field lines is non-zero, thereby allowing the magnetic field sensor 230 to detect the magnetic field lines. Preferably, the degree to which the AMP obstructs the magnetic field lines and allows them to be easily detected by the sensor 230 can be predetermined based on, for example, the following factors: (1) the output dynamic range of the sensor (e.g., the sensor's working output dynamic range relative to the sensor's full potential output dynamic range), (2) the engagement distance between the sensor and the AMP, and (3) the maximum detectable distance between the sensor and the AMP. As described herein, the AMP is a bi-functional metal plate whose second function is to generate a magnetic attraction force strong enough to magnetically couple (releasably couple) two devices together, e.g., the DP and RP of a pump device. Thus, the magnetic attraction force is another factor to consider when designing the AMP. 【0054】 Figure 2B shows a diametrically magnetized dipole circular magnet 250, similar to magnet 210 of Figure 2A, generating a magnetic field 260 similar to magnetic field 220 of Figure 2A. Figure 2B shows an example of an embodiment of the magnetic field sensing principle described in relation to Figure 2A. Magnetic field sensor 270 of Figure 2B is similar to magnetic field sensor 230 of Figure 2A. Magnet 250 includes a central opening 280, and magnetic field sensor 270 is located within opening 280 such that magnetic field sensor 270 is located at the center of magnet 250, such that magnetic field sensor 270 is circumferentially surrounded by magnet 250. 【0055】 2A, the direction of the magnetic field 260, when unobstructed, is parallel to the sensing area / plane of the magnetic field sensor 270 (the angle between the magnetic field lines and the magnetic field sensing area / plane of the sensor is zero degrees). Thus, the net magnetic field sensed by the magnetic field sensor 270 is zero. However, when an AMP (e.g., examples of AMPs are shown in FIGS. 5A-5C, 6A-6B, 7A-7B, 8, 9, 10B-10C, and 12A-12B) is brought close enough to the magnetic field sensing area of ​​the sensor 270, the magnetic field lines are obstructed (redirected) such that at least some of the redirected magnetic field lines form a non-zero angle with the magnetic field sensing area of ​​the sensor, thereby allowing the magnetic field sensor 270 to detect the magnetic field lines. 【0056】 3A shows a cross section of an axially magnetized dipole magnet 310 with a typical magnetic field. The magnet 310 is an axially magnetized dipole ring magnet. That is, the magnet 310 is magnetized along the magnet's axis 320, with the "N" pole being the top pole in this example. In the ring magnet 310 magnetization configuration, the magnet 310 generates a relatively uniform magnetic field 330 in the central region of the magnet 310. In the central region of the magnet 310, the direction of the magnetic field 330 is vertical from the "N" pole to the "S" pole, and thus the magnetic field 330 is aligned with the axis 320 of the magnet 310. 【0057】 FIG. 3A shows the magnetic field generation in the central region of the magnet 310. If the magnetic field sensor is placed in the central region of the magnet 310 so that the sensing surface is perpendicular to the axis 320, the sensor will always detect the magnetic field. Using this configuration to magnetically detect the engagement between two parts / devices, for example between the DP and RP of a pump device, is disadvantageous in terms of ability. If there is no electromagnetic interference with the two magnetic fields (in terms of detecting the engagement), it is beneficial to generate a second magnetic field that counteracts (cancels) the effect of the magnetic field 330 at the magnetic field sensor in the center of the magnet. The basic principle of actively canceling the effect of two magnetic fields with a magnetic field sensor placed in the center of the magnet is shown in FIG. 3B and explained below. In essence, one magnetic field is generated in a first direction by a first magnetic pole pair, while a counteracting (counteracting) magnetic field is generated in the opposite (counteracting) direction by a second magnetic pole pair. 【0058】 Figure 3B shows a cross section of a magnet configuration that includes two axially magnetized magnets (340, 350) that generate two counteracting magnetic fields that cancel each other's effect in a magnetic field sensor 360. Each of the axially magnetized magnets 340 and 350 generates a typical magnetic field, and the two magnets also magnetically interact with each other because each "N" pole interacts with two "S" poles. The vector directions of the magnetic fields generated by the two magnets are shown in Figure 3B. 【0059】 The two magnetic fields that two adjacent magnets (340, 350) generate in the space between them (i.e., the space they share) are relatively uniform and anti-parallel (i.e., point in opposite directions). This phenomenon is achieved by using pairs of north / south poles that generate magnetic fields in opposite directions. For example, axially magnetized magnet 340 includes a first pair of conjugate north / south poles that generate magnetic field 342 in a first direction that coincides with "symmetry" axis 370, and axially magnetized magnet 350 includes a second pair of conjugate south / north poles that generate magnetic field 352 in a second direction that also coincides with symmetry axis 370. However, magnetic field 342 and magnetic field 352 point in opposite directions. (Magnetic field 342 and magnetic field 352 are anti-parallel vector fields.) North pole 342 and south pole 344 constitute the first pair of conjugate poles, and south pole 352 and north pole 354 constitute the second pair of conjugate poles. 【0060】 Axially magnetized magnets 340 and 350 are designed to generate magnetic fields of the same field strength at the same point or region in the space between the two magnets, and the two magnets orient the two magnetic fields in opposite directions at that point or region so that they cancel each other out at that point or region. The point (or region) where the magnetic fields cancel each other out is called a "neutral point" (or "neutral region"). This type of magnetic field cancellation occurs because magnetic fields follow the principle of superposition, so that when two oppositely oriented magnetic fields are subtracted, the subtraction results in a zero magnetic field at that point or region if the two magnetic fields are of the same strength. Thus, if magnetic fields 342 and 352 have the same magnitude, given their opposite directions, the net magnetic field sensed (detected) by magnetic field 360 at the neutral point / region is zero. 【0061】 Similar to Figures 2A-2B, when neither magnetic field 342 nor magnetic field 352 is disturbed, the net magnetic field sensed by magnetic field sensor 360 is zero. This is because sensor 360 is at the neutral point where anti-parallel magnetic fields 342 and 352 counteract each other. However, when an AMP (not shown in Figure 3B) is brought close to the neutral point (close to the magnetic field sensing area of ​​sensor 360), magnetic fields 342 and 352 do not cancel each other due to the uneven disturbance that the AMP induces in the two magnetic fields. The uneven disturbance of the two magnetic fields allows the magnetic field to be detected by magnetic field 360 sensor. The above discussion regarding the AMP can also be applied to Figures 2B and 4A. 【0062】 Figure 4A shows an axially magnetized four-pole magnet 410 that generates two magnetic fields similar to magnetic fields 342 and 352 of Figure 3B. Magnet 410 (a particular example of a multi-pole magnet) is an example of an embodiment of the principle of superposition described in relation to Figure 3B. The circular (annular) magnet 410 has an axis coinciding with the Y-axis and includes a first portion 420 forming a first pair of conjugated N / S poles axially magnetized to generate a first magnetic field 440 in a first direction in a central region of magnet 410 (at magnetic field sensor 450), and a second portion 430 forming a second pair of conjugated N / S poles axially magnetized to generate a second magnetic field 460 in a second direction opposite to the direction of magnetic field 440 in a central region of magnet 410 (at magnetic field sensor 450). Similar to Fig. 3B, the axially magnetized magnet 410 generates two counteracting magnetic fields (440, 460) of equal strength that cancel each other out at the magnetic field sensor 450 due to the principle of superposition of two equal and antiparallel magnetic fields. (Magnetic field 440 and magnetic field 460 are antiparallel vector fields.) Fig. 4B shows a longitudinal cross section of the axially magnetized four-pole magnet 410 of Fig. 4A. The magnet 410 includes a central aperture 470, and the magnetic field sensor 450 is circumferentially surrounded by the magnet 410 since the magnetic field sensor 450 is located within the aperture 470 such that it is in the XY plane and centered with respect to the center of the magnet 410. 【0063】 Axially magnetized magnets (e.g., four-pole magnet 410 in Figs. 4A-4B) can generate relatively high density magnetic flux lines in the Y-axis direction in the figures, which means that the magnetic attraction force induced between the AMP and the magnet during coupling of the DP and RP of the pump device is larger for a four-pole magnet compared to the magnetic attraction force induced by a dipole magnet. 【0064】 5A-5C show an asymmetric metal plate (AMP) 500 according to one embodiment. Like all AMPs, the AMP 500 is planar and has an axis of asymmetry 510. (The AMP 500 is asymmetric about the axis of asymmetry 510, which coincides with the Z-axis of a Cartesian coordinate system.) The AMP 500, like other AMPs, is a monolithic body with a "flat plane" that coincides with the XZ plane of the Cartesian coordinate system. 【0065】 Referring to FIG. 5A, the AMP 500 includes three peripheral recesses, two side recesses 520 and 530, which in this example are symmetrical with respect to the X axis, and one front recess 540, which is parallel to the Z axis. The side recesses 520 and 530 are not necessarily symmetrical with respect to the X axis, and the recess 540 is not necessarily parallel to the Z axis, and is not necessarily symmetrical with respect to the X axis. For example, the recesses 520, 530, and 540 can have different sizes, shapes, widths, and / or recess depths (indentations), and the recesses may generally be inclined with respect to the X axis or the Z axis. The recess 540 is not necessarily symmetrical with respect to the X axis. The recess 540 creates an asymmetry with respect to or around the Z axis (i.e., there is no recess on the opposite side of the AMP 500) and with respect to the direction of the X axis, making the AMP 500 an asymmetric metal plate (AMP). Making an AMP (e.g., AMP 500) asymmetric with respect to or about the Z axis is advantageous in that electromagnetic interference induced by the AMP impacts the magnetic field involved, and thus the net magnetic field that can be detected by a magnetic field sensor (e.g., sensor 450 in FIGS. 4A-4B). (The asymmetry introduced into the AMP with respect to or about the Z axis causes the magnetic fields, e.g., magnetic fields 440 and 460, to be non-uniformly disturbed, causing the detectable net magnetic field to be greater than zero.) 【0066】 Structurally, the AMP 500 includes a first (main) section 550 that is configured to disturb (alter) the magnetic field generated by a magnet (e.g., magnet 110, 250, or 410) when the AMP 500 is at or near the magnet (and thus at or near a magnetic field sensor surrounded by the magnet). The degree to which the magnetic field generated by the magnet is disturbed (altered, distorted) by the AMP depends primarily on the size, shape, and material of the section 550. In general, the larger the area of ​​the first section 550, the greater the disturbance to the magnetic field and thus the larger the output signal of the magnetic field sensor 570 (FIG. 5C). However, because the dynamic output range of the sensor is limited (dependent, among other things, on the electrical design of the associated electrical circuitry), a trade-off is required between the design of the first section 550 and the output saturation magnetization value of the sensor. The first section 550 can be designed such that the limited dynamic output range of the sensor avoids a saturated magnetization condition. Section 550 is also configured to disrupt the magnetic field while simultaneously inducing a magnetic attraction force between the magnet and section 550. Generally, the larger the area of ​​first section 550, the greater the magnetic attraction force induced between first section 550 and the magnet. Thus, the design of section 550 also represents a trade-off between the dynamic range of the sensor's output and the strength of the resulting magnetic attraction force. 【0067】 AMP500 also includes a second (auxiliary) section, section 560. Section 560 is designed to generate additional magnetic attraction, thereby increasing the overall magnetic attraction induced between the magnet and AMP500. (Section 560 of AMP500 has negligible interference with the magnetic field.) 【0068】 5B shows the AMP 500 in three dimensions, and FIG. 5C shows the AMP 500 in proximity to a magnetic field sensor 570. (The proximity of the AMP 500 and the magnetic field sensor 570 refers to or indicates a suitable coupling or engagement between a component or part that includes the AMP 500 (e.g., the DP of a pump device) and a component or part that includes the magnetic field sensor 570 (e.g., the RP of a pump device).) 【0069】 6A-6B show in three dimensions an asymmetric metal plate (AMP) 600 according to another embodiment. The AMP 600 is a two-part metal plate including a first (main) part 610 and a separate second (auxiliary) part 620. The first part 610 has a similar function to the first section 550 of FIG. 5A, meaning that the part 610 is configured to: (1) disrupt (distort, change) the magnetic field generated by a magnet (e.g., magnet 110, 250, or 410) when the AMP 600 is at or near a magnet (i.e., at or near a magnetic field sensor surrounded by a magnet); and (2) simultaneously disrupt the magnetic field, generate a magnetic attraction force between the magnet and the first part 610 of the AMP 600. 【0070】 Second portion 620 has a similar function as second (auxiliary) section 560 of FIG. 5A, meaning that portion 620 is configured to generate an additional magnetic attractive force, thereby increasing the overall magnetic attractive force induced between the magnet and portion 620 of AMP 600. (Part 620 of AMP 600 may have negligible interference with the magnetic field.) 【0071】 The portion 610 includes a peripheral base 612 and a tab 630 that extends / projects (640) inwardly from the peripheral base 612 along the X-axis to the auxiliary portion 620. The tab 630 makes the AMP 600 asymmetrical with respect to the Z-axis. The size and shape of the tab 630 can be different or deviated from that shown in FIG. 6A as long as the asymmetry of the AMP 600 with respect to the Z-axis is maintained. (As described herein, the asymmetry of the AMP with respect to the Z-axis is advantageous in terms of the non-uniform disturbance it induces in the magnetic field generated by the magnet. The AMP can be designed in any manner, provided that the design of the AMP is consistent with the principles of non-uniform electromagnetic disturbance disclosed herein.) Although the AMP 600 is shown as symmetrical with respect to the X-axis, it is not essential for the proper functioning of the AMP 600 that the AMP 600 be symmetrical with respect to the X-axis. 【0072】 6B shows the AMP 600 adjacent to a magnetic field sensor 650. The proximity of the AMP 600 and the magnetic field sensor 650 refers to or indicates a coupling or engagement between the component or part that contains the AMP 600 (e.g., the DP of a pump device) and the component or part that contains the magnetic field sensor 650 (e.g., the RP of a pump device). As with the AMP 500, the design of the AMP 600 is generally a trade-off between the size and shape of the AMP 600's parts 610 and 620, the dynamic output range of the sensor, and the strength of the magnetic attraction force induced between the magnet and the AMP 600. 【0073】 7A-7B show an AMP (AMP700) according to one embodiment that is a modification of AMP600 of FIGS. 6A-6B. (FIG. 7B shows AMP700 in three dimensions.) AMP700 is a two-section AMP that includes a first (main) section 710 and a second (auxiliary) section 720. Main section 710 has a similar function to main portion 610 of FIGS. 6A-6B. That is, section 710 is configured to: (1) disrupt (distort, change) the magnetic field generated by a magnet (e.g., magnets 110, 250, or 410) when AMP700 is at or near a magnet (i.e., at or near a magnetic field sensor); and (2) simultaneously disrupt the magnetic field and generate a magnetic attraction force between the magnet and first section 710 of AMP700. 【0074】 Section 720 of AMP700 has a similar function as auxiliary section 620, i.e., section 720 is configured to generate additional magnetic attraction force and increase the overall magnetic attraction force induced between the magnet and AMP700. (Auxiliary section 720 of AMP700 may have negligible magnetic field interference.) 【0075】 Section 710 includes a peripheral base 712 and a tab 730 (major tab) that extends / projects (740) inwardly from the peripheral base 712 along the X-axis into the auxiliary section 720. An air gap 750 exists between the tab 730 and the peripheral base 722 of the auxiliary section 720. The tab 730 makes the AMP 700 asymmetrical with respect to the Z-axis, with line 780 being the axis of asymmetrical between sections 710 and 720. The size and shape of the tab 730 can differ or deviate from those shown in FIGS. 7A-7B, so long as the asymmetry of the AMP 700 with respect to the axis of asymmetrical 780 (and the Z-axis) is maintained. Although the tab 730 (and the entire AMP 700) is symmetrical with respect to the X-axis, it is not a necessary condition for the proper or acceptable functioning of the AMP 700 that the tab 730 be symmetrical with respect to the X-axis. 【0076】 AMP700 differs from AMP600 of FIGS. 6A-6B in that main section 710 and auxiliary section 720 are structurally interconnected by connecting elements (peripheral elements) 760 and 770 that make AMP700 a closed, flat, rounded body. Interconnecting main section 710 and auxiliary section 720 by peripheral interconnecting elements 760 and 770 has advantages during the manufacturing and assembly process. As with AMP500 and 600, the design of AMP700 is generally a trade-off between the size and shape of sections 710 and 720 of AMP700, the materials of construction of the AMP, the dynamic output range of the magnetic field sensor, and the strength of the magnetic attraction force induced between the magnet and the AMP. 【0077】 FIG. 8 illustrates an embodiment of an AMP 800 that is a modification of the AMP 700 of FIGS. 7A-7B. The AMP 800 is a two-section AMP that includes a first (main) section 810 and a second (auxiliary) section 820. Similar to the AMP 700, the main section 810 of the AMP 800 includes a peripheral base 812 and a first tab 830 (main tab) that extends / projects inwardly (L1) in the X-axis direction from the peripheral base 812 toward the auxiliary section 820. Also similar to the AMP 700 of FIGS. 7A-7B, the main section 810 and the auxiliary section 820 are structurally interconnected by peripheral interconnect elements 840 and 850. Similar to the AMP 700, the interconnection of the main section 810 and the auxiliary section 820 by peripheral interconnect elements 840 and 850 provides advantages in the manufacturing and assembly process. 【0078】 AMP800 differs from AMP700 in that AMP800 includes a second (auxiliary) tab 860. The auxiliary tab 860 extends / projects (L2) inwardly in the X-axis direction from the peripheral base 822 of the auxiliary section 820 toward the first tab 830, forming an air gap 870 between the main tab 830 and the auxiliary tab 860. The projection length L1 of the tab 830 of the main section 810 is greater than the projection length L2 of the tab 860 of the auxiliary section 810 (L1>L2). 【0079】 Main section 810 has similar functionality to main section 710 of Figures 7A-7B, i.e., main section 810 is configured to (1) disrupt (distort, change) the magnetic field generated by a magnet (e.g., magnets 110, 250, or 410) when AMP 800 is at or near a magnet (i.e., at or near a magnetic field sensor), and (2) simultaneously disrupt the magnetic field and induce a magnetic attraction force between the magnet and main section 810 of AMP 800. 【0080】 Auxiliary section 820 has a similar function as auxiliary section 720. That is, auxiliary section 820 is configured to generate additional magnetic attraction force and increase the overall magnetic attraction force induced between the magnet and AMP 800. (Auxiliary section 820 of AMP 800 may disrupt the magnetic field, but this is negligible.) Most of the additional magnetic attraction force provided by auxiliary section 820 is provided by tab 860. 【0081】 The size (width and / or length) and shape of the air gap 870, and the position of the air gap 870 along the X-axis are designed to provide or embody a trade-off between the intended electromagnetic interference induced in the AMT 800 in the magnetic field generated by the magnet (and therefore the resulting dynamic output range of the magnetic field sensor) and the magnetic attraction force induced by the AMT 800 towards the magnet. 【0082】 The design (including size and shape) of tabs 830 and 860 makes AMP 800 asymmetrical with respect to the Z axis, with line 880 being the axis of asymmetrical between sections 810 and 820. The size and shape of tabs 830 and 860 can differ or deviate from that shown in FIG. 8 so long as the asymmetry of AMP 800 with respect to the Z axis is maintained. Although tabs 830 and 860 (and AMP 800 as a whole) are symmetrical with respect to the X axis, it is not necessary for proper or acceptable functionality of AMP 800 that tabs 830 and 860 be symmetrical with respect to the X axis. 【0083】 Figure 9 illustrates various AMP designs according to some embodiments. The seven AMPs illustrated in Figure 9 are variations of AMT 700 of Figures 7A-7B, each of which includes a tab similar to tab 730 of Figures 7A-7B, i.e., tab 910 of Figure 9(1), tab 920 of Figure 9(2), tab 930 of Figure 9(3), tab 940 of Figure 9(4), tab 950 of Figure 9(5), tab 960 of Figure 9(6), and tab 970 of Figure 9(7). 【0084】 In the following description, "FIG. 9(1)" means "FIG. 9, Modification No. 1," "FIG. 9(2)" means "FIG. 9, Modification No. 2," and so on. 9(1), similar to FIGS. 7A-7B, shows an AMP including two peripheral connection elements 912 and 914 that interconnect a main section of the AMP and an auxiliary section of the AMP. The AMP also includes a central bridge connector (strip) 916 that interconnects the main and auxiliary sections of the AMP. FIG. 9(2) shows an AMP that includes two peripheral connection elements similar to peripheral connection elements 912 and 914 of FIG. 9(1), but does not have bridge connector 916. Instead of a bridge connector, the AMP of FIG. 9(1) includes an air gap 922. FIG. 9(3) illustrates an AMP that includes a bridge connector 932 similar to bridge connector 916 of FIG. 9(1), but without the two peripheral connection elements. FIG. 9(4) illustrates an AMP that includes bridge connectors and peripheral connection elements similar to bridge connector 916 and peripheral connection elements 914 of FIG. 9(1), but does not have the other peripheral connection elements (912) of FIG. 9(1). FIG. 9(5) shows an AMP that includes three bridge connectors (952, 954 and 956) but does not have the two peripheral connection elements (912, 914) of FIG. 9(1). FIG. 9(6) shows an AMP similar to the AMP of FIG. 9(5), which includes two of the three bridge connectors of FIG. 9(5) (i.e., bridge connectors 962 and 964), but does not include the two peripheral connection elements (912, 914) and the central bridge connector (954) of FIG. 9(5). Fig. 9(7) shows an AMP that is a combination of the AMPs of Fig. 9(1) and 9(5), i.e., the AMP of Fig. 9(7) includes two peripheral connection elements similar to the peripheral connection elements 912 and 914 of Fig. 9(1), plus three bridge connectors similar to the bridge connectors 952, 954, and 956 of Fig. 9(5). 【0085】 The bridge connectors shown in Figures 9(1) and 9(2)-9(7) are simply structural elements that interconnect the main section of the AMP with the auxiliary section of the AMP. Therefore, the bridge connectors can be made as thin as structurally possible (the bridge connectors can be a few millimeters wide) and have a very small area compared to the tab area of ​​the AMP. Therefore, the electromagnetic interference and magnetic attraction forces induced by the bridge connectors are negligible. 【0086】 10A-10C show a process of installing an AMP 500 on a DP 1010 of a pump device according to one embodiment. FIG. 10A shows a housing top cover 1000 of a DP of a pump device designed to accommodate a flat AMP, such as the AMP 500 of FIGS. 5A-5C, or a similar AMP. FIG. 10B shows the AMP 500 (an example AMP) firmly seated on the housing top cover 1000. FIG. 10C shows a two-reservoir DP 1010 of a pump device. All of the DPs shown in the figures and / or described herein, including the DP 1010, are manufactured by plastic injection molding. A DP made of plastic does not interfere with the magnetic interaction of the AMP with a magnet or the magnetic field sensor. (The plastic material is transparent to magnetic fields.) 【0087】 The assembly process for the DP 1010 includes, among other things, coupling the housing top cover 10000 (with the AMP 500 installed) to the DP 1010. In this example, the DP 1010 includes two drug reservoirs, one accessible through a luer connector 1020 and the other accessible through a luer connector 1030. 【0088】 11 shows another AMP (e.g., AMP600) securely mounted within the housing top cover 1000. (The reservoir is accessible through a luer connector, meaning that the reservoir can be filled with medication by the luer connector when the pump device is ready for operation, and emptied as medication is expelled from the reservoir during operation.) 【0089】 12A-12B show the installation of an AMP800 into a DP1210 of a pump device according to one embodiment. FIG. 12A shows the AMP800 of FIG. 8 securely mounted within the housing cover 1200. FIG. 12B shows the drug DP1210 of the pump device. The assembly process of the DP1210 involves bonding the housing cover 1200 (with the AMP800 mounted) to the DP1210. Similar to the DP1010 of FIG. 10C, the DP1210 also includes two drug reservoirs, each of which is accessible (operable) through a Luer connector. (The DP may include only one reservoir.) 【0090】 An AMP (e.g., AMP 500 of FIG. 10B, AMP 600 of FIG. 11, AMP 800 of FIG. 12A) can be secured to a housing cover (e.g., housing top cover 1000 of FIG. 10B and housing top cover 1200 of FIG. 12A) by swaging, where the AMP is pressed or packed into the surface of the housing cover. In certain embodiments, the AMP is sintered or hot pressed into the housing cover. In another embodiment, a cold swaging process is used to secure the AMP to the housing cover. In another embodiment, the AMP is secured to the housing cover by mechanically fitting the AMP into a recess formed in the housing cover, where the AMP has a size and shape that matches the size and shape of the recess in the housing cover. 【0091】 13A-13B show an example of a pump device (1300) including a RP (1310) and a DP (1320) according to one embodiment. Referring to FIG. 13A, the example RP 1310 has a T-shaped configuration including a body 1330 and a central foot 1340 that protrudes (extends) from the body 1330 of the pump. The body 1330 includes, among other things, an electric circuit board, a controller, a gear unit for driving two plunger heads in the DP 1320, two sleeves that house two drive screws that move the two plunger heads respectively, etc. The central foot 1340 includes, among other things, an electric motor for driving the gear unit and a magnet-sensor combination. The magnet-sensor combination includes a magnet configured to generate one or more magnetic fields in a preselected direction and a magnetic field sensor for sensing disturbances in the magnetic field when the DP 1320 is engaged with the RP 1310. In addition to generating a magnetic field with the magnet, the magnet is also used to magnetically attract an asymmetric metal plate (AMP). The magnet and magnetic field sensor (both elements not shown in FIGS. 13A-13B) are disposed at the distal end 1350 of the central foot 1340. The magnet is of a suitable size and shape to be received in the housing of the central foot 1340 and is configured to provide a magnetic field having a pattern, strength, and direction that, together with the AMP used, allows the pump controller to distinguish between an engaged state (the DP and RP of the pump device are engaged) and a disengaged state (the DP and RP of the pump device are disengaged) based on the output value of the magnetic field sensor. (The manner in which the controller distinguishes between the engaged and disengaged states of the pump device is described, for example, in connection with FIGS. 18A-18B.) 【0092】 The disposable portion 1320 of the pump device 1300 typically includes one or more drug reservoirs. By way of example, the DP 1320 includes two drug reservoirs (reservoirs 1360 and 1370). The disposable portion 1320 also includes an AMP 1380 that magnetically interacts with a magnet-sensor combination at 1350 when the RP 1310 and DP 1320 are engaged (1390). During engagement (1390), the distance (air gap) between the AMP 1380 in the DP and the magnet-sensor combination at 1350 in the RP is shortened, increasing the disturbance in the magnetic field sensed by the magnetic field sensor at 1350. The increased electromagnetic disturbance by the AMP 1380 affects the output value of the sensor, which allows the controller of the RP 1310 to determine whether the RP 1310 and DP 1320 are engaged or disengaged. During engagement of the RP 1310 and DP 1320, a drive nut 1362 coupled to the reservoir 1360 engages and is rotatable by a drive gear at 1332 to linearly move a drive screw 1364, thereby linearly moving the plunger head into the reservoir 1360. Similarly, a drive nut 1372 coupled to the reservoir 1360 couples to and is rotatable by a drive gear at 1334 to linearly move a drive screw 1374, thereby linearly moving the plunger head into the reservoir 1370. 【0093】 FIG. 13B shows the RP 1310 and DP 1320 in an engaged state. In the engaged state, the AMP 1380 is closest to the magnet at 1350. (In the engaged state, the AMP 1380 is magnetically attracted to the magnet, so the distance between the AMP 1380 and the magnet at 1350 is zero or close to zero.) This means that the distance (air gap) between the AMP 1380 and the magnetic field sensor at 1350 is minimal (non-zero) and the sensor is outputting a maximum output value according to the design specifications of the AMP and sensor used. For example, as shown in FIGS. 4A-4B, the magnetic field sensor 450 is slightly sunk into the magnet 410 (e.g., slightly recessed relative to the magnet surface) and is circumferentially surrounded by the magnet 410. This is why the distance between the AMP and the sensor is non-zero when the RP 1310 and DP 1320 are engaged. However, in other designs or embodiments, the sensing area of ​​the sensor and the outer surface of the magnet may be in the same plane, in which case the engagement distance between the sensor and the AMP may be zero. 【0094】 The AMP1380 may be similar to the AMP500, AMP600, AMP700, or AMP800, or may be a different design from the AMP500, AMP600, AMP700, or AMP800, as long as the design of the AMP simultaneously meets the two requirements described herein, that is, the AMP can generate electromagnetic interference detectable by a sensor in the magnetic field generated by the magnet, and can induce a sufficiently strong magnetic attraction between the AMP and the magnet to ensure the engagement between the RP and DP of the pump device. The commonality of all AMP designs is that the magnetic attraction induced between the AMP and the magnet should not be too strong so that a user, e.g., a Parkinson's patient, can comfortably separate the two parts. 【0095】 Detecting the engagement and engagement direction of the pump device from the sensor output 13A, for example, shows a two-reservoir DP1320 of a pump device that is symmetric about a central foot 1340 of the RP1310 of the pump device 1300. This symmetry allows the DP1320 to engage the RP1310 in a first engagement orientation shown in FIG13A (where reservoir 1360 is on top) or to engage the RP1310 in a second engagement orientation (where reservoir 1360 is below reservoir 1370), which is achieved by rotating the DP1320 180 degrees about the Y axis. 【0096】 In some embodiments, both reservoirs (e.g., reservoirs 1360 and 1370 in FIG. 13A) contain the same pharmaceutical agent, and the orientations of the two reservoirs are interchangeable, so the question "in which orientation should it be used" is not therapeutically significant (i.e., they can be used in the same way to achieve the same therapeutic outcome). However, in other embodiments, reservoirs 1360 and 1370 can each contain different pharmaceutical agents, and the question "in which orientation should it be used" is therapeutically significant, because the application of a particular drug therapy requires a particular DP engagement orientation. In these embodiments, the pump controller is configured to individually and independently control the two reservoirs according to the therapeutic requirements, for example, to deliver an intended amount of pharmaceutical agent #1 to the patient from, for example, reservoir 1360, followed by an intended amount of pharmaceutical agent #2 to the patient from reservoir 1370. Thus, in this case, before the controller activates the pump device to deliver the two pharmaceutical agents, the controller needs to ensure that the DP engagement orientation is appropriate for the intended therapy. 【0097】 Thus, detecting only the engagement between the DP and RP of the pump device as described herein is not sufficient for the normal operation of the pump device, since the orientation of the engagement may be important depending on the type of drug in each reservoir and / or the usage of the drug, and therefore, it is necessary to confirm whether the orientation of the engagement is correct. Thus, the controller can be configured to use the sensor output value to detect both of the following pump conditions: (1) the engagement status between the DP and RP of the pump device, and (2) the correct orientation of the engagement. The controller can be configured to output appropriate audible and / or visual cues to the patient, such as, for example, "engaged", "disengaged", "right orientation", "wrong orientation", etc. In terms of detecting the engagement, the DP1320 includes a simple and relatively inexpensive metal plate, which makes it easy to make the DP1320 disposable after use. 【0098】 FIG. 14 shows a magnet-sensor combination 1400 according to one embodiment. The magnet-sensor combination 1400 includes a flat rounded (ring) magnet 1410 and a magnetic field sensor 1420. As described herein with respect to other magnetic field sensors, the magnetic field sensor 1420 is in the XZ plane, is centrally located (and circumferentially surrounded) by the magnet 1410, and is slightly recessed (recessed) with respect to the outer surface of the magnet 1410 (the upper surface in FIG. 14). Positioning the magnetic field sensor slightly below the surface of the ring magnet 1410 and centrally located on the ring magnet 1410 has advantages in terms of the strength and direction of the magnetic field in the space near the magnetic field sensor. That is, positioning the magnetic field sensor relative to the magnet as described herein and / or as shown in the figures (e.g., Figures 1, 2B, 3B, 4A-4B, 14, 15A-15B, 16A-16B) causes the output signal of the magnetic field sensor to be zero when the RP and DP of the pump device are disengaged and increases the sensitivity of the magnetic field sensor to electromagnetic interference caused by the AMP in the magnetic field when the RP and DP are engaged. 【0099】 The magnet 1410 can be a dipole magnet, for example similar to the dipole magnet 250 of FIG. 2B, or a multi-pole magnet, for example similar to the four-pole magnet 410 of FIG. 4A. In some embodiments, the magnet can have more than four poles. In general, the magnet can include a number n (n=1, 2, 3) pairs of conjugated poles (N / S), for example three (n=3) pairs of conjugated poles (i.e., three "north" poles and three conjugated "south" poles). A magnet with n pairs of conjugated poles is magnetized diametrically, axially, or both diametrically and axially. The magnet-sensor combination 1400, or a magnet-sensor combination similar to the magnet-sensor combination 1400, is included (e.g., is part of) the RP of the pump device, for example, a portion of the RP 1310 of FIGS. 13A-13B. 【0100】 The magnet-sensor combination 1400 also includes electrical terminals 1430 for powering the magnetic field sensor 1420 with a power source located within the RP of the pump device and transmitting the output signal of the magnetic field sensor 1420 to a controller of the associated RP, e.g., a controller located in the body 1330 of the RP 1310. (The power source and controller are not shown in FIG. 14.) 【0101】 A commonality between all magnets, sensor sensing surfaces, and AMPs in all figures is that they are all in the XZ plane (or parallel to the XZ plane) with the Y axis perpendicular (perpendicular) to those planes. Another feature common to all magnets, magnetic field sensors, and AMPs is that the asymmetric axis of the AMP (e.g., asymmetric axis 780 of AMP700, asymmetric axis 880 of AMP800) is coincident with (or parallel to) the Z axis. Orienting the magnets, sensor sensing surfaces, and AMPs as shown in the figures and described herein facilitates optimization of electromagnetic interference by the AMPs, which in turn facilitates sensing and detection of the engagement state (including engagement orientation) by the pump device controller. 【0102】 Figures 15A and 15B respectively show a longitudinal partial cross section 1500 and a widthwise partial cross section 1502 of a pump device with the DP and RP engaged, according to one embodiment. Referring to Figure 15A, the DP includes two drug reservoirs (1510, 1520) that are structurally similar to reservoirs 1360 and 1370 of Figure 13A. Drug reservoir 1510 is accessible through luer port 1530, and drug reservoir 1520 is accessible through luer port 1540. Luer ports 1530 and 1540 are structurally similar to luer ports 1020 and 1030 of Figure 10C. 【0103】 The RP includes a magnet-sensor combination similar to magnet-sensor combination 400 of FIG. 14, and the DP includes an asymmetric metal plate (AMP). The magnet-sensor combination includes an annular (ring-shaped) magnet 1550 similar to magnet 1410 of FIG. 14, and a magnetic field sensor 1560 similar to magnetic field sensor 1420 of FIG. 14. The AMP is designated 1570. Also shown in FIGS. 15A-15B is an electrical terminal 1580 through which a power source (located in the RP of the pump device) supplies electricity to the magnetic field sensor 1560 and transmits the output signal of the magnetic field sensor 1560 to a controller for processing in the controller. (The power source and controller are not shown in FIGS. 15A-15B.) 【0104】 16A-16B show an example of a magnet-sensor-metal plate (MMP) setup, according to one embodiment. Fig. 16A-16B show the relationship P [%] between the sensitive area of ​​the magnetic field sensor and the overlap of the asymmetric metal plate (AMP), according to one embodiment. (Fig. 16B is an enlarged view of detail A of Fig. 16A) 【0105】 The magnet-sensor combination 1600 includes a magnet 1610 and a magnetic field sensor 1620. The magnet-sensor combination 1600 and AMP 1630 are designed such that when the associated DP and RP of the pump device are engaged, the tab 1650 partially overlaps the magnetic field sensor 1620. (The larger the inward protrusion 1640 of the tab 1650, i.e., the larger the value of X1 in FIG. 16B, the greater the overlap between the sensing areas of the tab 1650 and the magnetic field sensor 1620.) The overlap ratio "P" can be calculated as P=(X1 / X2)×100. (Xi can represent length or area, depending on the AMP used.) 【0106】 When the overlap ratio is zero (X1=0), the disturbance caused by the tab 1650 in the magnetic field generated by the magnet 1610 may not be detectable by the magnetic field sensor 1620, or the difference between the sensor's output signal in the disengaged state and the sensor's output signal in the engaged state may be too small for the controller to reliably distinguish between these two states. Furthermore, when X1=0, the magnetic attraction induced between the tab 1650 and the magnet 1610 may be too weak to properly couple the DP of the pump device to the RP. On the other hand, the configuration with X1=X2 also has problems with respect to the disturbance (magnetic deflection) induced in the magnetic field by the AMP. That is, when the overlap ratio is 100% or close to 100%, the disturbance induced by the tab 1650 in the magnetic field generated by the magnet 1610 may be too large, causing the magnetic field sensor 1620 to reach a saturated magnetization state before the DP and RP of the pump device are engaged. As a result, the controller may erroneously interpret the output signal (saturation magnetization value) of the magnetic field sensor 1620 as indicating engagement of the DP and RP before the engagement of the DP and RP occurs. In essence, the saturation magnetization of the sensor is a state in which the actual signal that needs to be measured cannot be measured because the dynamic output range of the sensor has been exceeded. Thus, the saturation magnetization value of the sensor output is the limit value of the dynamic output range of the sensor. (The lower the saturation magnetization value of the sensor, the smaller the dynamic output range of the sensor.) Furthermore, when X1=X2, the magnetic attraction force induced between the tab 1650 and the magnet 1610 may be too strong for a user (e.g., a PD patient) to disengage the DP from the RP of the pump device. 【0107】 Referring to FIGS. 16A - 16B, when the sensor reaches its saturation magnetization state, there may be a non - negligible error between the actual (true) distance (spacing) between AMT1630 and sensor 1620 and the distance (spacing) estimated by the controller from the saturation magnetization output value of the sensor. (An example of the saturation magnetization point of the magnetic field sensor is shown in FIG. 17.) 【0108】 Based on two constraints (i.e., detectable magnetic interference and favorable magnetic attraction force), the value of X1 is preferably greater than zero to obtain a sufficient magnetic attraction force and detectable magnetic interference, and less than X2 to prevent an overly strong magnetic attraction force and / or reaching saturation magnetization (i.e., X1 needs to satisfy the condition 0 < X1 < X2). The overlapping value for trade - off can be, for example, 50% (i.e., X1 = X2 / 2). The two constraints mentioned for the overlapping ratio P also apply to AMP500, AMP600, AMP700, AMP800, and other designed AM Ps. 【0109】 FIG. 17 shows an example output response of a linear Hall effect sensor. A Hall effect sensor can act as an analog transducer, converting the magnetic field sensed by the sensor into a voltage proportional to the magnetic field. A Hall effect sensor can sense both positive and negative magnetic fields. A linear Hall effect sensor can give a linear response similar to that shown in graph 1700 by applying a fixed offset to the output of the sensor when the Hall effect sensor senses no magnetic field (null point 1710, which corresponds to a null voltage of approximately 2.4V). As the positive magnetic field increases above zero Gauss (G), the output voltage of the sensor increases linearly beyond the null voltage 1710 until it reaches the positive saturation magnetization point 1720 (i.e., the positive saturation magnetization value V(s1) at +300G). Similarly, as the negative magnetic field is increased in the opposite direction (i.e., below zero Gauss), the output voltage of the sensor increases linearly relative to the null voltage 1710 until it reaches the negative saturation magnetization point 1730 (i.e., the negative saturation magnetization value V(s2) at -300G). Thus, in the example of Figure 17, the dynamic output range (voltage) of the sensor ranges from V(s1) to V(s2) and the sensor can reliably measure magnetic field strengths ranging from -300G to +300G. 【0110】 13A , which shows the DP 1320 of the pump device 1300 before being coupled to the RP 1310 in a first orientation, with the drive nut 1362 engaging the drive gear 1332 and the drive nut 1372 engaging the drive gear 1334. However, because the DP 1320 is structurally symmetrical about the central foot 1340 of the RP 1310, the DP and RP can also be coupled in a second orientation, with one part (e.g., the DP 1320) rotated 180 degrees relative to the first orientation (i.e., rotated about the Y axis) such that the drive nut 1362 engages the drive gear 1334 and the drive nut 1372 engages the drive gear 1332. 【0111】 This feature enhances the usability of the pump device 1300 because the patient does not have to worry about the orientation of the RP 1310 and the DP 1320 when combining the two parts, RP 1310 and DP 1320. However, in another embodiment, the RP 1310 and the DP 1320 need to be engaged in a specific orientation in order for the pump device to be operable. In accordance with the present invention, ensuring that the engagement orientation of the DP is an operable orientation can be achieved using the asymmetric feature of the asymmetric metal plate (AMP), as described herein. 【0112】 As described herein and shown in the drawings, the asymmetric metal plate (AMP) is asymmetric with respect to the Z axis (see, for example, AMPs 500, 600, 700, 800, and 1630). Thus, rotating the DP of the pump device 180 degrees (rotating around the Y axis) with respect to the RP in the XZ plane also rotates the AMP 180 degrees (rotating around the Y axis) with respect to the magnetic field sensor in the XZ plane. Due to the asymmetric nature of the AMP with respect to the Z axis, the electromagnetic interference that the AMP causes at the sensor in the first engagement orientation in the magnetic field is different from the electromagnetic interference that the AMP causes at the sensor in the second engagement orientation. As a result, the output signal of the Hall effect sensor for the first engagement orientation is different from the output signal of the Hall effect sensor for the second engagement orientation. Thus, the output signal of the magnetic field sensor for the null voltage (null point 1710 in FIG. 17) can be used to distinguish between the two engagement orientations of the DP, for example, as described in FIGS. 18A-18B. 【0113】 18A-18B show saturation magnetization curves 1810 and 1812 versus non-saturation magnetization curves 1820 and 1822, according to one embodiment. (FIG. 18B shows an expanded view of dotted box B in FIG. 18A.) Curves 1810 and 1812 are associated with an AMP in which a magnetic field sensor (e.g., sensor 1420, FIG. 14) is designed to reach a saturated magnetization state. In the example shown in FIGS. 18A-18B, the output saturation magnetization value of the sensor is 2014 for a magnetic field in a first direction and zero (0) for a magnetic field in a second direction opposite the first direction. Thus, the sensor's operable dynamic output range (0÷2014) is the maximum range in this example. (The saturation magnetization value of a magnetic field sensor generally depends on the type of sensor and the design of the associated electrical circuitry, e.g., operating voltage, etc.) 【0114】 Curve 1810 shows the output value (i.e., digital value) of the sensor as a function of the distance or gap / spacing between the AMP and the sensor when the AMP is in a first orientation relative to the sensor (the first orientation is referred to herein as the SIDE-B orientation). Curve 1812 shows the output value of the sensor as a function of the distance or gap / spacing between the AMP and the sensor when the AMP is in a second orientation (SIDE-A) relative to the sensor (the second orientation is referred to herein as the SIDE-A orientation). The second orientation (SIDE-A) of the AMP can be obtained by rotating the AMP 180 degrees around the Y axis in the XZ plane (see, for example, the XY plane and Y axis in FIG. 10C). For ease of understanding, the relative spatial positions of the AMP, magnet, magnetic field sensor, DP and RP of the pump device are shown using the same XYZ coordinate system, as shown, for example, in FIGS. 2B, 4B, 5B, 6B, 7B, 10C, 13A, 15A-15B and 16A. Curves 1820 and 1822 are similar to curves 1810 and 1812, respectively, except that curves 1820 and 1822 are associated with an AMP design that avoids sensor saturation magnetization when DP and RP are engaged, leaving a useful (e.g., safety) output margin relative to the sensor saturation magnetization value. (Curves 1810, 1812, 1820, and 1822 were obtained using the same simulation methodology.) 【0115】 SIDE-B orientation: Saturation magnetization vs. non-saturation magnetization For curve 1810, when the AMP is moved away from the magnetic field sensor by a distance greater than 3.6 mm (in this example), the output value (digital code / value Sa) of the sensor is null value Snull (Snull=approximately 1060). This is because at distances greater than 3.6 mm, the AMP does not interfere with the magnetic field at the sensor, so the net magnetic field sensed by the sensor is zero or close to zero, which corresponds to the sensor's null value, approximately 1060. (The null line 1830 corresponds to the sensor's null value, Snull=approximately 1060). However, as the AMP (in the SIDE-B orientation) gets closer to the sensor, the electromagnetic interference caused by the AMP gradually increases, which causes a corresponding increase in the sensor's output value until at zero distance the sensor outputs the upper saturation magnetization value 2014 (saturation magnetization point 1814 in FIGS. 18A-18B). 【0116】 For curve 1820, a similar correlation between space (between AMP and sensor) and the output value of the sensor is shown as curve 1810. That is, as the AMP (SIDE-B orientation) is successively brought closer to the sensor, the electromagnetic interference caused by the AMP increases progressively, which causes a corresponding increase in the output value of the sensor until at zero distance the sensor outputs a non-saturated magnetization value 1699 (point 1824 in FIG. 18B). Thus, the output value 1699 of the sensor at the null space leaves a safety margin of 315 (i.e., 2014-1699=315). 【0117】 The safety margin is useful, for example, for detecting a failure of a sensor (or other electrical circuit element) by the controller of the RP of the pump device when the DP and RP of the pump device are engaged. For example, if the DP and RP of the pump device are engaged but the sensor outputs a saturation magnetization value, the controller can determine that the sensor or some other electrical element is not functioning properly and can therefore react by outputting a warning message (audible and / or textual) to the patient and simultaneously stop the delivery of medicine from the pump device to the patient. (This feature is useful for all malfunctions where the malfunction causes the magnetic field sensor to be in a saturated magnetization state.) Thus, using a non-saturated magnetization curve similar to curve 1820 is more beneficial in terms of detecting malfunctions than using a saturated magnetization curve similar to curve 1810. 【0118】 SIDE-A orientation: Saturation magnetization vs. non-saturation magnetization For curve 1812, when the AMP is moved away from the magnetic field sensor by a distance greater than 3.6 mm (in this example), the sensor output value is null / point (approximately 1060). This is because at distances greater than 3.6 mm, the AMP does not interfere with the magnetic field at the sensor, so the net magnetic field sensed by the sensor is zero or close to zero, which corresponds to a sensor output value of approximately 1060. However, as the AMP (in this invention, SIDE-A orientation) is brought closer to the sensor, the electromagnetic interference caused by the AMP gradually increases, which causes a corresponding increase in the sensor output value until at zero distance the sensor outputs a low saturation magnetization value, 0 (point 1816 in FIGS. 18A-18B). 【0119】 For curve 1822, a similar correlation between the distance (between the AMP and the sensor) and the output value of the sensor is shown as curve 1812. That is, as the AMP (SIDE-A orientation) is continuously brought closer to the sensor, the electromagnetic interference caused by the AMP gradually increases, which causes a corresponding increase in the output value of the sensor until the sensor outputs a non-saturated magnetization value 277 (point 1826 in FIG. 18B) at zero distance. Thus, the output value of the sensor at zero distance, 277, leaves a safety margin of 277 (i.e., 277-0=277). Similar to curve 1820, curve 1822 also shows that the safety margin is useful, for example, for detecting a failure of the sensor (or other electrical circuit element) by the controller of the RP of the pump device when the DP and RP of the pump device are engaged. 【0120】 Magnitude of the sensor's output at zero spacing (M): Saturated magnetization vs. unsaturated magnetization The sensor output magnitude "M" for each distance between the AMP and the sensor can be calculated as M=|Sa-Snull|, where Sa is the actual (e.g., measured) output value of the sensor and Snull is the null value of the sensor. For the saturation magnetization curves 1810 and 1812, the sensor output magnitude M for zero distance in the first orientation of the AMP (curve 1810, SIDE-B) is 954 (M=|2014-1060|=954). In the second orientation of the AMP (curve 1812, SIDE-A), the sensor output magnitude M for zero distance is 1060 (M=|0-1060|=1060). For the non-saturation magnetization curves 1820 and 1822, in the first orientation of the AMP (curve 1820, SIDE-B), the sensor output value M for zero distance is 639 (M=|1699-1060=639), and in the second orientation of the AMP (curve 1822, SIDE-A), the sensor output value M for zero distance is 783 (M=|277-1060|=783). 【0121】 The magnitude M, or span, of the sensor output value of the non-saturated magnetization curve is small compared to the magnitude M, or span, of the sensor output value of the saturation magnetization curve. However, as described herein, the non-saturated magnetization curve provides a useful safety margin. The safety margin can be designed as a trade-off between the magnitude M of the sensor output value and the ability of the pump controller to detect failures of the magnetic field sensor and / or other circuit elements. In other words, it is beneficial to increase the M value by using the saturation magnetization value of the sensor without sacrificing the ability of the controller to detect failures of the magnetic field sensor and / or other circuit elements. 【0122】 Null point and distinction between SIDE-B and SIDE-A orientation As described in connection with FIG. 17, the magnetic field sensor has a null voltage 1710, which divides the dynamic output range of the sensor into a positive segment and a negative segment, with the positive segment corresponding to a positive magnetic field direction and the negative segment corresponding to a negative magnetic field direction. (The null value of a bipolar magnetic field sensor is the signal (analog or digital) that the sensor outputs when it does not sense any magnetic field.) In the example of FIG. 18A-18B, the null value Snull is a digital value of about 1060 and is used to distinguish between the two orientations of AMP (SIDE-B, SIDE-A), because all sensor output values ​​associated with the first orientation (SIDE-B) are greater than the null value of about 1060 (all sensor output values ​​are above the null line 1830), whereas all sensor output values ​​associated with the second orientation (SIDE-A) are less than the null value of about 1060 (all sensor output values ​​are below the null line 1830). 【0123】 Curve 1812 is a mirror image of curve 1810 approximately about null line 1830. Similarly, curve 1822 is a mirror image of curve 1820 approximately about null line 1830. Mirror curves such as curves 1812 and 1822 result from the AMP being asymmetric with respect to an asymmetric axis that coincides with the Z-axis. By imparting asymmetry to the AMP and positioning (orienting) the AMP relative to the sensor (and the magnets surrounding the sensor) such that the asymmetric axis of the AMP is perpendicular to the X-axis, the direction of the magnetic field sensed by the magnetic field sensor due to electromagnetic interference caused by the AMP can be reversed. That is, when the AMP is positioned (orientated) relative to the sensor in a SIDE-B orientation, the magnetic field sensed by the sensor due to electromagnetic interference from the AMP has a first orientation, which in this example is the orientation of curve 1820. However, when the AMP is rotated 180 degrees about the Y axis (i.e., positioned in the direction of SiDE-A), the direction of the magnetic field sensed by the sensor is reversed due to electromagnetic interference from the AMP in this orientation, resulting in the direction of curve 1822 in this example. 【0124】 Working Example Applying curve 1810 (FIGS. 18A-18B) to FIGS. 15A-15B (illustrating magnet 1550, sensor 1560, and AMP 1570), when the DP is not engaged with the RP and the distance (spacing) between the AMP 1570 and the sensor 1560 is greater than about 3.6 mm in this example, the magnetic field(s) generated by the magnet 1550 is not disturbed (or no electromagnetic interference is detectable), and thus the net magnetic field sensed by the sensor 1560 is zero or close to zero. Thus, the output signal of the sensor 1560 is null, about 1060 (see null line 1830). When the DP (with AMP 1570) is brought closer to the RP (with sensor 1560), i.e., when the spacing between the DP and RP is less than about 3.6 mm during engagement, the electromagnetic interference induced by the AMP 1570 at the sensor 1560 increases as the AMP 1570 moves closer to the sensor 1560. As a result of the increased electromagnetic interference at the sensor, the output value of the sensor 1560 also increases. (The closer the AMP 1570 is to the sensor 1560, the greater the sensor output value will be due to the increased electromagnetic interference.) 【0125】 Assuming that the saturation magnetization value of the magnetic field sensor 1560 (for the sensor response curve 1810) is 2014, the AMP 1570 can be designed so that the curve 1810 reaches the saturation magnetization value of the sensor 2014 when the spacing between the AMP 1570 and the sensor 1560 is zero or close to zero. On the other hand, designing the AMP 1570 so that the output value of the sensor is the saturation magnetization value (2014 in this example) for the spacing of zero means maximizing the sensitivity limit of the spacing measurement, and therefore the accuracy of the spacing measurement. On the other hand, if the DP and RP are engaged (spacing between DP and RP is zero) but the sensor, or the associated electronics, is bad or malfunctioning, the sensor output signal cannot be used to detect that bad condition. This is because the sensor's saturation magnetization output value can be used to detect either the spacing between the AMP and the sensor is zero (i.e., detection engagement state) or a problem in the circuit (i.e., related matters), but not both. To be able to use the sensor output signal to detect zero (or close to zero) AMP-sensor distance and faults in the sensor, electronics or software, the AMP 1570 can be designed such that when the distance between the AMP 1570 and the sensor 1560 is zero or close to zero, the sensor output value is slightly lower (e.g. 1699 in the sensor response curve 1820) compared to the saturation magnetization output value 2014 of the sensor. The curve 1820 solves this problem by, on the one hand, the sensor output value 1699 indicates that the AMP-sensor distance is zero or close to zero, and, on the other hand, the sensor output jumps to the saturation magnetization value when the sensor and / or other system components are faulty. Thus, when the DP and RP of the pump device are engaged, the two sensor output values ​​1699 and 277 (e.g. the controller in the RP) allow to distinguish between an engaged state and a faulty operating state. The AMP 1570 can therefore be designed such that the sensor 1560 can output (for example) such an under-saturation magnetization output-distance response curve. 【0126】 Figure 19 compares sensor output response curves 1910 and 1920 of two different AMP designs, according to one embodiment. The two AMPs compared in Figure 19 are AMP800 of Figure 8 (labeled AMP#1 in Figure 19) and AMP500 of Figures 5A-5C (labeled AMP#2 in Figure 19). Curves 1910 and 1920 represent simulation results for AMP#1. Curves 1930 and 1940 represent simulation results for AMP#2. 【0127】 A comparison of curves 1910 and 1930 shows that the AMP#1 design is more advantageous than the AMP#2 design because at zero intervals, the sensor output range (magnitude M) of the AMP#1 design spans a significantly larger span (e.g., 1773-1040=733) than the sensor output range of the AMP#2 design (e.g., 1514-1040=474). A comparison of mirror curves 1920 and 1940, respectively, shows similar behavior. (The sensor output value of 1040 corresponds to the null value of the null line 1950.) Furthermore, the AMP#1 design provides a larger magnetic attraction force compared to the AMP#2 design, and this magnetic characteristic applies to both 2-pole and 4-pole magnet configurations, as the specific comparative information example below shows. Typical magnetic attraction force of a two-pole magnet configuration 1. AMP♯1:7.0[N] 2. AMP♯2:4.5[N] Typical magnetic attraction force of a 4-pole magnet configuration 1. AMP♯1:11.0[N] 2. AMP♯2:6.0[N] 【0128】 Examples of factors to consider when designing AMP 1. The AMP design (e.g. AMP500, AMP600, AMP700, AMP800, etc.) dictates how high the sensor's output response curve (SIDE-B orientation) is relative to the sensor's null value / line, or how low the curve (SIDE-A orientation) is relative to the sensor's null value / line. The AMP design also dictates the curvature of the sensor's output response curve. Figure 19 shows an example of the impact of this factor. FIG. 19 shows two sensor output response curves for AMP#1 (e.g., curve 1910 in the SIDE-B orientation of AMP#1 and curve 1920 in the SIDE-A orientation of AMP#1) as well as two sensor output response curves for AMP#2 in comparison (e.g., curve 1930 in the SIDE-B orientation of AMP#2 and curve 1940 in the SIDE-A orientation of AMP#2). The different designs of these two AMPs (AMP#1 and AMP#2) cause the sensors to respond differently when the distance between the AMPs and the sensors is the same. For example (see SIDE-B orientation in FIG. 19), AMP#1 causes the sensor to output a value of 1773 (curve 1910) when the AMP-sensor distance is zero, while AMP#2 causes the sensor to output a different value (e.g., value 1514 on curve 1930) when the AMP-sensor distance / spacing / gap is also zero. The sensor output values ​​are similarly different for the SIDE-A orientations of AMP#1 and AMP#2 (e.g., value 419 on curve 1920 for AMP#1 versus value 715 on curve 1940 for AMP#2. The sensor output values ​​similarly vary from AMP-sensor distance zero to the engagement threshold distance (ETD), Dth. (e.g., as shown in FIG. 19, the sensor output is a null value, approximately 1040 (null line 1950), for all cases where the AMP-sensor distance is greater than Dth (in this example, Dth≈5.2 mm). Dth is shown at 1960 in FIG. 19.) 2. The type of sensor is one factor that determines the magnitude of the sensor's output signal for a given AMP design and AMP-sensor distance. 3. The preferred magnetic attraction between the AMP and the magnet. The greater the preferred magnetic attraction, the larger the area of ​​the AMP required. Increasing the size of the AMP may increase the effect of the AMP on the output response of the sensor until saturation magnetization is reached. 4. The actual distance between the AMP and the sensor is zero after assembling the DP and RP of the pump device. The distance between the AMP and the sensor may be subject to constraints imposed by the design of the DP and RP of the pump device. This means that in practice, for one design, the engagement distance between the AMP and the sensor may be, for example, 0.00 mm, and for another design, it may be, for example, 0.05 mm, 1.3 mm, 2.0 mm, etc. 5. Electronics and operating voltages. For example, changing the supply voltage may change the maximum output span of the sensor. 【0129】 20A-20B illustrate the calibration of the engagement threshold distance / spacing according to one embodiment. The engagement threshold distance (ETD) Dth is a threshold distance or spacing between the AMP and the magnetic field sensor that the controller (for example) uses to distinguish between engaged and disengaged states of the DP and RP of the pump device. If the actual distance Da between the AMP and the sensor detected by the controller is greater than the ETD (i.e., Da>Dth), the controller determines that the DP of the pump device is not engaged with the RP of the pump device. However, if the actual distance Da between the AMP and the sensor is equal to or less than the ETD (i.e., Da≦Dth), the controller determines that the DP and RP of the pump device are engaged. 【0130】 During normal operation of the pump device, the controller of the pump device determines the distance, Da, between the AMP and the magnetic field sensor based on the sensor output. Since the sensor output and the associated distance / spacing between the AMP and the sensor vary with pump designs, a calibration process must be performed to associate the sensor threshold output (Sth) with the specific threshold distance (Dth) for the pump device being calibrated. In essence, the calibration is performed by engaging the DP with the RP and reading the sensor output (Sth) corresponding to the engagement distance. Assuming the engagement orientation is SIDE-B, during normal operation of the pump device, if the sensor output is equal to or greater than the Sth value, it indicates that the DP and RP of the pump device are engaged. The calibration described herein applies to any design of the AMP, magnetic field sensor, magnet, DP and RP of the pump device. 【0131】 Curve 2010 shows the output value of a sensor (e.g., sensor 1560 of FIGS. 15A-15B) as a function of the distance or gap / spacing between the AMP (e.g., AMP 1570 of FIGS. 15A-15B) and the sensor when the AMP (and thus the DP) is in a first engagement orientation (SIDE-B) relative to the sensor (and thus the RP). Curve 2020 shows the output value of the sensor as a function of the distance or gap / spacing between the AMP and the sensor when the AMP is in a second engagement orientation (SIDE-A) relative to the sensor. (Curves 2010 and 2020 were obtained using simulation methods.) 【0132】 As described herein, for two engagement orientations of the AMP (SIDE-A and SIDE-B), the second engagement orientation of the AMP (SIDE-A) is obtained by rotating the AMP 180 degrees around the Y axis in the XZ plane (e.g., the XYZ coordinate system used in Figures 2B, 4B, 5B, 6B, 7B, 10C, 13A, 14, 15A-15B is common to the DP and RP of all AMPs, sensors, magnets, and pump devices shown in the figures and described herein). 【0133】 In the first calibration process, the DP containing the AMP is engaged with the RP including a magnet, a magnetic field sensor, and a controller in a first engagement orientation (e.g., the SIDE-B orientation), and the magnetic field sensor outputs a first value Sth1 corresponding to an engagement threshold distance (ETD) Dth. In this example, the engagement threshold distance is 1.5 mm (i.e., Dth = 1.5 mm), and the output value of the sensor (engagement value, Sth1) corresponding to the above engagement distance is 1304 (i.e., Sth1 = 1304). All sensor output values Sa in the SIDE-B orientation are above the null line 2050 (i.e., the output values of all sensors are greater than the null value, approximately 1110). 【0134】 All sensor output values Sa that are the same as or greater than 1304 (Sth1) indicate that the engagement (SIDE-B orientation) is maintained. When the output value Sa of the sensor becomes less than 1304, i.e., in the case of 1110 < Sa < 1304 (1110 is the null value Snull of the sensor), it indicates that the distance between the AMP and the sensor is greater than Dth (i.e., Da > Dth). This means that the DP and the RP of the pump device are disengaged. Therefore, the sensor output value Sth1 = 1304 becomes the first calibration value used by the controller of the pump device to distinguish between the engaged state and the disengaged state in the first orientation (SIDE-B orientation) of the DP with respect to the RP. 【0135】 In the second calibration process, the DP is engaged with the RP in a second orientation (e.g., the orientation corresponding to SIDE-A), and the magnetic field sensor outputs a second value Sth2 that reflects the engagement state in the second orientation (the orientation of SIDE-A). In this example, the engagement distance is also 1.5 mm (i.e., Dth = 1.5 mm), and the output value of the sensor (engagement value Sth2) is 1000 (i.e., Sth2 = 1000). (The engagement distance for both orientations is 1.5 mm in this example. However, depending on the design of the pump device, the engagement distance may vary between pump devices or with the engagement orientation) All sensor output values Sa in the orientation of SIDE-A are below the null line 2050 (i.e., the output values of all sensors are less than the null value, approximately 1110). 【0136】 All sensor output values Sa that are the same as or less than 1000 indicate that the engagement (orientation of SIDE-A) is maintained. When the output value of the sensor Sa becomes greater than 1000, i.e., in the case of 1000 < Sa < 1110 (1110 is the null value Sull), it indicates that the DP and RP of the pump device are disengaged. Therefore, the sensor output value Sth2 = 1000 becomes another calibration value used by the controller of the pump device to distinguish between the engaged state and the disengaged state in the second engagement orientation (orientation of SIDE-A) of the DP with respect to the RP. 【0137】 Therefore, the controller of the pump device can determine the following two with the output value of a single sensor: (1) the engagement state (engaged or disengaged), and (2) the direction of engagement of the DP (the direction of engagement of SIDE - B or SIDE - A). For example, the controller of the pump device can determine the direction of engagement of the DP with respect to the RP (e.g., SIDE - B or SIDE - A) by comparing the output value of the sensor with the null value Snull of the sensor to determine whether the output value of the sensor is greater than, equal to, or less than the null value Snull of the sensor. For example, when the output value Sa of the sensor is greater than the null value of the sensor (i.e., Sa > Snull), the direction of engagement is SIDE - B, and when the output value of the sensor is less than the null value of the sensor (i.e., Sa < Snull), the direction of engagement is SIDE - A. 【0138】 Regarding the determination of the engagement state (engaged or disengaged), when the output value Sa of the sensor is equal to or greater than the first threshold value (i.e., Sa ≥ Sth1), the controller determines that the DP is engaged with the RP in the SIDE - B direction. Similarly, when the output value Sa of the sensor is less than the second threshold value (i.e., Sa < Sth2), the controller determines that the DP is engaged with the RP in the SIDE - A direction. 【0139】 Therefore, during the calibration process, the controller monitors the output value of the sensor for both directions of engagement of the DP (SIDE - B and SIDE - A), and after confirming the two coupling threshold values Sth1 and Sth2 corresponding to a specific direction of engagement, the controller ends the calibration process. (The coupling threshold value Sth1 corresponds to the direction of engagement SIDE - B, and the coupling threshold value Sth2 corresponds to the direction of engagement SIDE - A) Thereafter, the controller uses these two coupling threshold values (Sth1, Sth2) to detect the direction of engagement during the normal operation of the pump device. The method by which the controller uses these two coupling threshold values is shown in Figure 21 and will be described below. The calibration process of pairing the DP with a specific RP can be part of the manufacturing and / or assembly process of the pump device. 【0140】 Figure 21 shows a method for determining the engagement between the DP and RP of a pump device according to an embodiment. As described herein (e.g., FIGS. 17, 18A-18B, 20A-20B), the null value Snull can distinguish between the engagement direction SIDE-B and the engagement direction SIDE-A. The engagement determination method of FIG. 21 is based on the relationship between the two calibration thresholds (Sth1, Sth2) described for FIGS. 20A-20B and the null value (Snull) of the sensor, i.e., the relational expression Sth2 < Snull < Sth1. 【0141】 In step 2100, the DP of the pump device (e.g., DP1310 in FIG. 13A) is magnetically engaged with the RP of the pump device (e.g., RP1320 in FIG. 13A) by the magnetic attraction force induced between the AMP in the DP (e.g., AMP1380 in FIG. 13A) and the magnet in the RP (e.g., the magnet at 1350 in FIG. 13A). In step 2110, the controller included in the RP of the pump device continuously reads the output value Sa of the magnetic field sensor included in the RP of the pump (e.g., the sensor at 1350 in FIG. 13A). 【0142】 In step 2120, the controller compares the value of Sa with a first engagement threshold Sth1 to determine whether the DP and RP are engaged in the SIDE-B orientation. If the value of Sa is equal to or greater than the value of Sth1 (this condition is indicated as Y in step 2120), the controller determines in step 2130 that the DP is engaged with the RP in the SIDE-B orientation and continues to monitor the value of Sa in step 2110 to determine whether the engagement is maintained or interrupted. If the engagement is disengaged or interrupted, which occurs during drug delivery to the patient, the controller stops the delivery of the drug and outputs a corresponding alarm (auditory and / or visual) to the pump user (e.g., the patient). However, if the value of Sa is less than the value of Sth1 (this condition is indicated as N in step 2120), the controller determines that the DP is not engaged with the RP in the SIDE-B orientation and proceeds to check for possible engagement in the SIDE-A orientation. 【0143】 At step 2140, the controller compares the value of Sa with a second engagement threshold Sth2. If the value of Sa is equal to or less than the value of Sth2 (this condition is indicated as Y at step 2140), the controller determines at step 2150 that the DP is engaged with the RP in the SIDE-A orientation, and continues to monitor the value of Sa at step 2110 to see if the engagement is maintained or interrupted. If the engagement is disengaged or interrupted, and this occurs during delivery of the drug to the patient, the controller stops the delivery of the drug and outputs a corresponding alarm (audible and / or visual) to the patient. However, if the value of Sa is greater than the value of Sth2 (this condition is indicated as N at step 2140), the controller determines at step 2160 that the DP is not engaged with the RP in any orientation (i.e., neither in the SIDE-A orientation nor in the SIDE-B orientation), and continues to monitor the value of Sa at step 2110 to detect the engagement state (engaged, engaged orientation, disengaged) of the pump device at any time. The controller can continuously check the value of Sa at a predetermined time interval, which may vary depending on, for example, the operation mode of the pump device. For example, during normal delivery of a drug to a patient, the controller can check the value of Sa frequently, for example, once every t1 seconds, and when the pump is not delivering a drug to a patient, the controller can check the value of Sa less frequently, i.e., once every t2 seconds (t2>t1). The value of t1 can be, for example, 0.05 seconds, 0.1 seconds, or 1.0 seconds, and the value of t2 can be, for example, 5.0 seconds, 7.0 seconds, or 10.0 seconds. 【0144】 Prevention of mechanical damage during partial detachment of RP and DP parts The invention disclosed herein can be incorporated, for example, into a wearable infusion pump device. When a user is using such an infusion pump device, a force may be applied unintentionally, inadvertently, or accidentally to either the RP or the DP, causing the two parts to momentarily and partially separate from each other. Partial separation of the DP from the RP means that the RP and the DP are neither fully engaged nor fully disengaged. Partial separation of the DP and the RP during pump device operation (e.g., during drug dose delivery) is detrimental to the operation of the pump device in that it may cause damage (e.g., wear, destruction) to various parts of the pump device, especially the moving parts involved in transferring the motor force from the RP to the plunger rod of the reservoir in the DP. To avoid this problem, a relationship between the actual output value (Sa) of the sensor and the distance (spacing) between the RP and the DP is used to determine a safe distance range (SDR) between the RP and the DP. (An example of the relationship between the actual output value Sa of the sensor and the distance D between the RP and the DP is shown as curve 1820 in FIG. 18A.) 【0145】 When the distance between the RP and DP is within the SDR, the engagement of the RP and DP is considered complete and therefore safe to operate. When the distance between the RP and DP exceeds the SDR, even if partial, it is considered unsafe to operate. Thus, when the actual distance between the RP and DP as measured (by the pump device controller) exceeds the SDR, the pump device controller may momentarily stop operation of the pump device (e.g., stop delivery of a dose of drug) until the distance between the RP and DP is again within the SDR, indicating that full engagement between the RP and DP has resumed. 【0146】 The SDR depends on (originates from) the design and configuration of the various actual participating parts, e.g., the size, shape, and location of the sensor in the RP, and the size, shape, and location of the AMP in the DP. As an illustration, the SDR can include all RP-DP distances between 0.6 mm and 2.0 mm, such that if the RP-DP distance momentarily exceeds 2.0 mm, the pump device's (RP's) controller pauses (stops, interrupts, holds) drug delivery, and resumes drug delivery when the RP-DP distance returns to within the SDR range. 【0147】 22 illustrates a method for controlling operation of a pump device according to another embodiment. At step 2200, a safe distance range (SDR) for engagement between the DP and RP of the pump device is pre-determined. 【0148】 At step 2210, the pump device controller monitors the output value Sa of the magnetic field sensor, which corresponds to the net magnetic field sensed by the magnetic field sensor, and at step 2220, the controller determines the distance (spacing) D between DP and RP from the value of Sa. 【0149】 At step 2230, the controller compares the distance D to a pre-determined SDR to determine whether the value of D is within the predetermined SDR. The controller can transition between operating, pausing, or interrupting the pump device based on the comparison result. That is, if the value of D is within the pre-determined SDR (this condition is shown as Y at step 2230), the controller continues normal operation of the pump device at step 2240, and continues monitoring (2250) the value of Sa to detect changes (if any) in the distance D according to the intended treatment plan. If the value of D exceeds the pre-determined SDR (this condition is shown as N at step 2230), the controller stops (interrupts) the operation of the pump device at step 2260 as a precautionary measure to prevent damage to moving parts of the DP or RP or parts of both the pump device. Operation of the pump device when the distance D is within the SDR may include executing the treatment plan. Stopping or interrupting operation of the pump device when the distance D exceeds the SDR may include pausing execution of the treatment plan until the distance D between the RP and DP is back within the SDR range. 【0150】 Referring again to step 2230, the controller of the pump device uses a change criterion to determine whether operation of the pump device should proceed normally (e.g., step 2240) or be suspended (e.g., step 2260) based on a comparison of the distance D between the DP and RP of the pump device to a safe distance range (SDR). However, the change criterion also has a time component. That is, if the distance D between the DP and RP of the pump device exceeds the SDR, the controller can use a change parameter that is, for example, a function of the deviation of the distance D between the DP and RP from the SDR and the duration of the deviation. For example, if the value of D exceeds the SDR, the smaller the deviation of the distance D from the SDR (i.e., the closer D is to the SDR), the longer the pump device will remain in that state before the controller stops or suspends operation of the pump device. Conversely, if the value of D exceeds the SDR, the greater the deviation of the distance D from the SDR, the shorter the time the controller will allow the pump device to remain in that state before the controller stops or suspends operation of the pump device. The reasoning behind this is that when the distance D is closer to the SDR, the likelihood of damage to the DP and RP is low and the controller may allow the pump device to remain in this state for a longer period of time without risking the integrity of the pump device. Conversely, when the deviation of the distance D from the SDR is large, the likelihood of damage to the DP and RP is large and the controller may allow the pump device to remain in the at-risk state for only a relatively short period of time to avoid risking the integrity (e.g., mechanical integrity) of the pump device. 【0151】 Positioning of magnetic field sensors: dipole magnets versus multipole magnets As described herein, when the DP and RP of the pump device are disengaged, the net magnetic field sensed by the magnetic field sensor (e.g., Hall effect sensor) is zero, regardless of the number of poles or magnetization direction of the magnet. To facilitate this feature, the magnetic field sensor is placed at the center of the magnet and positioned to position its sensing surface depending on the magnet's magnetization configuration (e.g., dipole, 4-pole). For example, in the case of dipole magnetization (FIGS. 2A-2B), the magnetic field sensor (230, 270) is positioned with its sensing surface parallel (or generally parallel) to the magnetic flux lines (220, 260) generated by the dipole magnet (210, 250) such that the sensing surface of the sensor is perpendicular to the Y-axis in the figures (FIGS. 2A-2B). In the case of a four-pole magnetization (FIGS. 4A-4B), the magnetic field sensor (450) is oriented with its sensing plane perpendicular (or generally perpendicular) to the magnetic flux lines (440, 460) generated by the four-pole magnet (magnet 410) and to the Y-axis of the figure (FIGS. 4A-4B). Thus, the sensing area / plane of the sensor is oriented perpendicular to the Y-axis regardless of the number of poles (dipole or multipole) or magnetization configuration of the magnet. 【0152】 The difference between dipole magnetization and multipole magnetization (four-pole magnetization described herein is a special example of multipole magnetization) is the direction of the unobstructed (i.e., original) magnetic flux lines relative to the sensing surface of the sensor. (By "unobstructed direction" or "original direction" we mean the direction of the magnetic flux lines when the DP and RP of the pump device are disengaged. The unobstructed direction of the magnetic field is changed (obstructed) or deflected / redirected by the AMP at the magnetic field sensor when the DP and RP of the pump device are engaged.) 【0153】 AMP, magnet, sensor To facilitate the generation of magnetic attraction between the AMP and the magnet, the AMP is made of a ferrous material. For example, iron, cobalt, nickel, and alloys composed of these ferromagnetic metals are strongly attracted to magnets. As described herein, in addition to generating magnetic attraction, the AMP also has another function: the AMP deflects (redirects) magnetic field lines at the magnetic field sensor when the DP and RP of the pump device are engaged. To facilitate the feature of deflecting (redirecting) magnetic field lines, the material selected for the AMP is characterized by having a relatively high magnetic permeability. (The higher the magnetic permeability of the AMP, the greater the number of magnetic field lines deflected by the AMP and the greater the deflection effect of the AMP.) Thus, the AMP includes a metal that is magnetizable and conducts magnetic flux when it is near a magnet (i.e., when the DP is engaged with the RP of the pump device), but is not magnetized by the magnet and does not conduct magnetic flux when the AMP is away from the magnet (i.e., when the DP is disengaged from the RP of the pump device). 【0154】 The magnets shown in the various figures herein and described herein (e.g., magnet 110 of FIG. 1, magnet 250 of FIG. 2B, magnet 410 of FIG. 4A, magnet 1410 of FIG. 14, magnet 1550 of FIGS. 15A-15B, and magnet 1610 of FIG. 16A) are permanent magnets. Permanent magnets differ from temporary magnets by their ability to remain magnetized without the influence of a nearby external magnetic field. The magnets described herein are made of neodymium-iron-boron (NdFeB, NdFe 14 B) a magnet, which is currently considered to be the strongest permanent magnet. 【0155】 The magnetic field sensors shown in the various figures and described herein (e.g., sensor 120 of FIG. 1, sensor 270 of FIG. 2B, sensor 450 of FIG. 4A, sensor 570 of FIG. 5C, sensor 650 of FIG. 6B, sensor 1420 of FIG. 14, sensor 1560 of FIGS. 15A-15B, and sensor 1620 of FIGS. 16A-16B) may be 1-axis magnetic field sensors, 2-axis magnetic field sensors, 3-axis magnetic field sensors, Hall effect sensors, semiconductor magnetoresistors, ferromagnetic magnetoresistors, fluxgate sensors, inductive magnetometers, permanent magnet linear contactless displacement sensors, magnetoresistive position sensors, magnetic torque sensors, etc. The magnet-metal plate-sensor setup is designed to accommodate the type of magnetic field sensor used. 【0156】 The articles "a" and "an" are used herein to refer to one or more than one (e.g., at least one) of the grammatical object of the article, depending on the context. By way of example, an element may mean one element or multiple elements, depending on the context. The term "including" is used herein to mean, and is used interchangeably with, the phrase "including but not limited to." The terms "or" and "and" are used herein to mean, and are used interchangeably with, the term "and / or," unless the context clearly indicates otherwise. The term "such as" is used herein to mean, and is used interchangeably with, the phrase "such as but not limited to." 【0157】 Having thus described the embodiments of the present invention, it will be apparent to one skilled in the art that modifications of the disclosed embodiments are within the scope of the present invention. Alternative embodiments therefore include functionally equivalent objects / articles. For example, an asymmetric metal plate (AMP) may have a different design (e.g., different shape, size and / or material) than the AMP described herein and shown in the drawings, provided that the AMP of the different design functions as described herein. Typically, the disposable portion of the pump device may include one drug reservoir or two drug reservoirs, each of which may contain levodopa or carbidopa, or a combination of levodopa and carbidopa. Any permanent magnet may be used, provided that it functions in the manner described herein. Features of certain embodiments may be used in other embodiments described herein. The present disclosure relates to a pump device including a DP and a RP. However, the present disclosure may also relate to (e.g., may be implemented by, used with, or for) other types of two-part devices, such as pumps, syringes, therapeutic drug delivery devices, etc. Accordingly, the following claims are not limited by this disclosure.

Claims

[Claim 1] A pump device (1300) for delivering liquid pharmaceuticals to a user, wherein the pump device (1300) A magnetic field sensor (1420) having a magnetic field sensing area, A magnet (1410) surrounds the magnetic field sensor (1420) in the circumferential direction and magnetizes it in such a way as to generate one or more magnetic fields in a direction that makes the net magnetic field sensed by the magnetic field sensor (1420) zero, Includes a controller that reads the output value of the magnetic field sensor (1420), Reusable portion (1310), The reusable portion (1310) and the disposable portion (1320) which can be magnetically engaged and coupled Includes, The aforementioned disposable portion (1320) The disposable portion (1320) includes a metal plate (1380) configured to be magnetically attracted to the magnet (1410) in order to magnetically engage the reusable portion (1310), During the engagement, the magnetic field sensor (1420) is configured to deflect one or more of the magnetic fields in the magnetic field sensing area by magnetic force so that the net magnetic field sensed by the magnetic field sensor (1420) is greater than zero. A pump device (1300) characterized in that the controller is configured to determine the engagement state between the disposable portion (1320) and the reusable portion (1310) from the output value (Sa) of the magnetic field sensor (1420) corresponding to the sensed net magnetic field. [Claim 2] The device (1300) according to claim 1, wherein the magnetic field sensing area, the magnet (1410), and the metal plate (1380) each form a plane that coincides with or is parallel to the X-Z plane of the Cartesian coordinate system and is perpendicular to the Y axis of the Cartesian coordinate system. [Claim 3] The device (1300) according to claim 2, characterized in that the magnet (1410) includes a central opening, and the magnetic field sensor (1420) is positioned at the center of the opening of the magnet (1410) at a point that coincides with the origin of the Cartesian coordinate system. [Claim 4] The device (1300) according to claim 2, characterized in that the metal plate (1380) is asymmetric with respect to an asymmetric axis that coincides with the Z axis, and the AMP (700), where the asymmetric axis is the asymmetric metal plate, is divided into a main section (710) and an auxiliary section (720), the main section (710) is configured to induce a magnetic attractive force between the main section (710) and the magnet (1410) when the disposable portion (1320) is in proximity to the reusable portion (1310), and at the same time, the main section (710) is configured to deflect one or more of the one or more magnetic fields, and the auxiliary section (720) is configured to induce a magnetic attractive force between the auxiliary section (720) and the magnet (1410) when the disposable portion (1320) is in proximity to the reusable portion (1310). [Claim 5] The device (1300) according to claim 1, characterized in that the metal plate (1380) non-uniformly deflects one or more of the one or more magnetic fields, and the deflection is detectable by the controller. [Claim 6] The device (1300) according to claim 1, characterized in that the metal plate (1380) is configured such that the magnetic field sensor (1420) does not reach saturation magnetization when the disposable portion (1320) and the reusable portion (1310) are engaged, and the controller is configured to distinguish between the engaged state and a malfunction state associated with the magnetic field sensor (1420) reaching saturation magnetization. [Claim 7] The device (1300) according to claim 1, characterized in that the disposable portion (1320) includes a pharmaceutical reservoir (1360), and the controller is configured to determine the engagement state by comparing the output value (Sa) of the magnetic field sensor (1420) with a threshold (Sth). [Claim 8] The device (1300) according to claim 1, characterized in that the controller is configured to check the value of Sa once every t1 seconds when the disposable portion (1320) and the reusable portion (1310) of the pump device (1300) are engaged or when the pump device (1300) is actually delivering a drug to the patient, and to check the value of Sa once every t2 seconds (t2 > t1) when the pump (1300) is not delivering a drug to the patient. [Claim 9] The disposable portion (1320) includes two pharmaceutical reservoirs (1360, 1370), The aforementioned controller, The output value (Sa) of the magnetic field sensor (1420) is compared with the null value (Snull) of the magnetic field sensor (1420) to distinguish whether the disposable part (1320) and the reusable part (1310) are engaged in a first engagement direction (SIDE-B) or whether the disposable part (1320) and the reusable part (1310) are engaged in a second engagement direction (SIDE-A). or The output value (Sa) of the magnetic field sensor (1420) is compared with a first threshold (Sth1) to determine that the engagement of the disposable part (1320) is in the first engagement direction (SIDE-B), and the output value (Sa) of the magnetic field sensor (1420) is compared with a second threshold (Sth2) to determine that the engagement of the disposable part (1320) is in the second engagement direction (SIDE-A), in which case Sth1 > Snull and Sth2 < Snull are configured. The device (1300) according to claim 1, characterized in that the controller is configured to optionally output auditory and / or visual instructions regarding the engagement of the disposable portion (1320) and the reusable portion (1310), and / or the accuracy of the orientation of the engagement. [Claim 10] The device (1300) according to claim 2, characterized in that the disposable portion (1320) includes two pharmaceutical reservoirs (1360, 1370), and the metal plate (1380) is asymmetric with respect to an asymmetric axis coinciding with the Z axis, so that the first engagement orientation (SIDE-B) of the disposable portion (1320) and the second engagement orientation (SIDE-A) of the disposable portion (1320) can be detected and distinguished. [Claim 11] The device according to claim 1, characterized in that the magnet (1410) is a permanent magnet configured by at least one of the following: (1) The first configuration is characterized in that the permanent magnet is a diametrically magnetized dipole magnet configured to generate a magnetic field parallel to the magnetic field sensing area such that the net magnetic field sensed by the magnetic field sensor (1420) is zero or close to zero, and when the disposable portion (1320) and the reusable portion (1310) are engaged, the metal plate (1380) deflects the magnetic field in the magnetic field sensing area, so that the net magnetic field sensed by the magnetic field sensor (1420) is greater than zero. (2) The permanent magnet is a multipole magnet containing a number n (n = 1, 2, 3, ...) pairs of conjugate poles (N / S), and the permanent magnet is magnetized in the diametrical direction or the axial direction, or magnetized in both the diametrical and axial directions, and the multipole magnet is configured to generate multiple magnetic fields in opposite directions in the magnetic field sensing area such that the net magnetic field sensed by the magnetic field sensor (1420) is zero or close to zero, by canceling out opposing magnetic fields from each other in the magnetic field sensing area. Optionally, the multipole magnet is a tetrapole magnet including a first conjugate pole pair (N / S) magnetized in a first axial direction and a second conjugate pole pair (N / S) magnetized in a second axial direction opposite to the first direction, and the second configuration is characterized in that when the disposable portion (1320) and the reusable portion (1310) are engaged, the metal plate (1380) deflects the magnetic field in the magnetic field sensing area, so that the magnetic field sensed by the magnetic field sensor (1420) is greater than zero. [Claim 12] The device (1300) according to claim 4, characterized in that the main section and auxiliary section of the (AMP) are configured by a configuration selected from at least one of the following: (1) The first configuration is characterized in that the main section and auxiliary section of the asymmetrical metal plate are separate, unconnected sections. (2) A second configuration characterized in that the main section and auxiliary section of the AMP form a single monolithic object. (3) A third configuration characterized in that the main section of the AMP includes a main tab, the main tab extends inside the AMP toward the auxiliary section of the AMP, and optionally the auxiliary section of the AMP includes an auxiliary tab, the auxiliary tab extends inside the AMP toward the main tab, and optionally the main tab extends further inside the AMP than the auxiliary tab, and the main tab has a larger surface area than the surface area of ​​the auxiliary tab. [Claim 13] The main section (710) of the AMP (700) partially overlaps the magnetic field sensing area when the disposable portion (1320) and the reusable portion (1310) are engaged, and the ratio of the partial overlap is P[%], where optionally P[%] is 50% (±10%), or optionally the value of P[%] is the magnetic attractive force induced between the magnet (1410) and the AMP (700) and the magnetic field sensing area of ​​the AMP (700) The device (1300) according to claim 4, characterized in that there is a trade-off relationship between the magnetic deflection of the induced magnetic field, or the controller can optionally distinguish between the engagement state and a fault state that causes the magnetic field sensor (1420) to reach saturation magnetization, characterized in that the value of P [%] is selected so that the magnetic field sensor (1420) does not reach saturation magnetization when the disposable portion (1320) and the reusable portion (1310) are engaged. [Claim 14] The device (1300) according to claim 4, characterized in that the design of the AMP is in a trade-off relationship between the magnetic attractive force induced between the magnet (1410) and the AMP (700) and the magnetic field deflection in the magnetic field induced by the AMP (700) in the magnetic field sensing area. [Claim 15] Furthermore, (1) the controller determines the distance between the disposable portion (1320) and the reusable portion (1310) from the output value (Sa) of the magnetic field sensor (1420) corresponding to the sensed net magnetic field, (2) the controller compares the distance with the SDR, which is the safe distance range, and (3) based on the comparison result, the controller switches between operating the pump device (1300) and suspending the operation of the pump device (1300), and optionally operates the pump device (1300) when the distance is within the SDR, or suspends the operation of the pump device (1300) when the distance exceeds the SDR. The device (1300) according to claim 1, wherein a roller is configured, and optionally, the transition parameter is a function of (1) the value of the distance D between the disposable portion (1320) and the reusable portion (1310) and (2) the time T that the distance D between the disposable portion (1320) and the reusable portion (1310) has, and the controller is configured to use the transition parameter to transition between the operating state and the interrupted state of the pump device (1300), and optionally, the operation of the pump device (1300) includes executing a treatment plan, and the interruption of the operation of the pump device (1300) includes interrupting the execution of the treatment plan.

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