By Sean Fenske, Editor-in-Chief
Pharmaceuticals are delicate yet critical components for patients who require them. As such, it’s vital to ensure they can be delivered uninterrupted, at the dosage rate required, and reliably. This makes their delivery mechanism an essential device that must perform flawlessly.
To this end, when developing a pump that will travel on the patient’s body, the challenges are only increased. Finding the right partner to address the questions developers have about the pump, motor, gearing, sensors, and any other related components can be the difference between a successful project and one with a higher probability of failure.
Fortunately, Peter van Beek, the Medical Business Development Manager at maxon, took time to address a number of questions about how the company tackles drug delivery pump projects. He speaks to several topics that are important to consider, including the types of motor assemblies used for these types of applications, the challenges involved with portable pumps, and various options to think about.
Sean Fenske: When it comes to drug delivery devices, what types of motor assemblies are being used for these applications?
Peter van Beek: There are many different pump types utilized in the delivery of drugs. Both large- and small-volume infusion pumps move the drug, feeding, or saline fluids, often via rotary or linear peristaltic pumps; driven by a DC brushed or brushless motor-gearbox-sensor assembly. Syringe pumps use a similar drive assembly arrangement that turns a lead screw-plunger assembly. Another pump type, ambulatory pumps, are smaller mobile pumps capable of running off battery or wall power. As such, they use smaller, DC motor-gear-sensor assemblies engineered to run at peak efficiencies and have long running lifetimes. Hormone (insulin) pumps run on batteries as well and need to be as small, efficient, and lightweight as possible, as they are worn daily on the body. Generally, an insulin pump drive assembly has a diameter of 8-10mm or less and consists of a DC motor-gearbox-sensor assembly that drives a lead screw-syringe-plunger.
Smaller and smaller pump designs have continued to push the physical dimensions of the individual drive components and how these components are assembled to each other. maxon can easily integrate components into a custom design (either in-line or U-shaped—motor and gearbox next to each other, in parallel).
Lifetime expectations for a particular pump design dictate whether a DC brushed or brushless motor is utilized. A DC brushless motor provides a far superior lifetime.
"If you can imagine it, maxon can build it.”
Lifetime expectations for a particular pump design dictate whether a DC brushed or brushless motor is utilized. A DC brushless motor provides a much longer lifetime.
Fenske: What are the significant challenges involving drug delivery devices used on a patient (such as a portable pump) and how is maxon addressing them?
van Beek: maxon’s ironless core DC brushed and brushless motors were originally developed for cordless shavers in the 1960s with a design goal of providing the maximum run time between battery recharging. The ironless core motor design greatly surpasses iron-core designs and simply provides the highest efficiency possible from a DC motor, making it a preferred motor for pump designs using a battery. Combine this motor with maxon’s UP (ultra performance) planetary gearbox with one to four stage designs all having efficiencies greater than 90% and you have a winning drive assembly.
Considerable R&D has been spent by major pump manufacturers to develop disposable drug pumps or “patch pumps.” This portable battery-powered pump is thrown away after it has delivered its drug payload, which can be over several days. These new pumps are challenging traditional dedicated long-lasting pumping approaches, which are costly, take years to engineer and qualify, and are difficult to bring to market. These pump designs that are adhered to the body demand the lowest possible motor assembly costs, smallest size, lightest weight, and highest efficiency. A huge challenge for these pump designs is finding a low-cost drive assembly that provides the required validated and reliable quality for the delivery of the life-sustaining drug. maxon is exploring alternative motor designs that use less expensive disposable components and novel ways of automating construction to reduce costs.
Fenske: As the delivery devices for drugs become smaller, are you, in turn, seeing requests for smaller drive assemblies for these products?
van Beek: Yes. For many years, maxon has been making brushless and brushed motors as small as 4mm in diameter but also with diameter steps of 6, 8, 9.2, 10, 12mm, etc. These steps go all the way up to 90mm.
Fenske: How are drug delivery motors being powered and does that limit the size the entire assembly can be? What are the challenges here?
van Beek: Depending upon the pump type, different power sources are used—wall power, batteries, or both. With modern battery technologies, the size of the pump is not limited by the battery. Pole-mounted infusion pumps are larger in design due to the large amount of mechanical hardware packed in the box and redundant power source capabilities.
maxon strives and achieves the highest efficiency and longest life motor assemblies possible with the use of the highest quality subcomponents and ironless core design (lower inductance winding in comparison to iron core designs). Additionally, the ironless core motor design provides the added benefits of longer brush life, low EMI emissions (less disturbance of surrounding tightly packed electronics in proximity to the drive assembly), and no preferred rotor position (no detent).
Fenske: Is maxon capable of developing an entire pump system or just providing drive assembly components and control electronics? What additional inputs can maxon provide to improve the overall design?
van Beek: Some customers only want to purchase a high-quality servo drive assembly, which is incorporated into their larger design. maxon is happy to accommodate this approach or provide a larger mechatronic subassembly part of the pump. It’s entirely up to them.
maxon has a 60-year history of engineering DC brushed and brushless motors, gears, sensors, and drive electronics into complex drive assemblies for some of the world’s most demanding applications. This same engineering talent and expertise easily translates into building complex pumping systems, such as a linear or rotary peristaltic pumps, for example. Typically, these designs incorporate maxon motor’s CIM (ceramic-injection-molded) or MIM molded components, gearing, sensors, and mold-injected and turned parts. You can be assured the quality and engineering you associate with maxon’s catalog products will also be found in your custom pump design.
During a meeting to determine the drive assembly or a weekly meeting for a complete pump project, you can count on maxon to provide additional beneficial feedback, beyond the components. For example, thermal considerations, mounting, potential customizations, dealing with radial and axial loading of the output shaft for best life outcomes, and di-electric breakdown testing might be discussed.
Fenske: What considerations should drug delivery device developers keep in mind about the motor portion?
van Beek: Due to the criticality of drug delivery and the associated risk to patients, quality must be maintained at the highest level from start to finish. This is a primary focus for maxon and something we excel at.
For example, we must make a determination of voltage range, which the battery will cycle through from fully charged to minimum voltage. The drive assembly must be capable of providing the desired speed and torque at the lowest voltage and simultaneously not provide unacceptable speed and torque at the maximum voltage condition.
At the start of the design, determination of the torque and speed for the new pumping system is one of the larger challenges for the engineering team. Sure, the design may be analyzed on paper or in models, but assumptions are always made. True characterization comes by assembling real parts and using a maxon drive assembly as an analysis tool. maxon’s ironless core design provides a linear relationship between torque & current draw. Also, voltage & speed have a linear relationship. Thus, by placing the motor into the design and simply measuring the current and voltage, the torque and speed can be determined very precisely and quickly. Once the true parameters of an unknown system are determined, the final sizing of the motor, selection of gear ratio, and approach to highest efficiency are possible. Using the motor assembly for torque and speed analysis makes this aspect of the design simple and straightforward.
Fenske: Do you have any additional comments you would like to share based on any of the topics we discussed or something you’d like to tell medical device manufacturers?
van Beek: My final thoughts relate to quality. It is highly recommended your quality and design efforts run in parallel on your path to serial production. maxon employs a project milestone approach to both design and quality, making development steps organized and understandable. Most design efforts leave quality as an afterthought and if your time to market is critical, you do not want the quality requirements to stand in the way.
Please consider maxon with our exceptional Swiss-based engineering talent and creativity, quality processes, collaborative design and quality approach to projects, and our vast historical experience with the world’s smallest drive assemblies for your next drug delivery pump or drive assembly.
Click here to find out more about maxon >>>>>
Pharmaceuticals are delicate yet critical components for patients who require them. As such, it’s vital to ensure they can be delivered uninterrupted, at the dosage rate required, and reliably. This makes their delivery mechanism an essential device that must perform flawlessly.
To this end, when developing a pump that will travel on the patient’s body, the challenges are only increased. Finding the right partner to address the questions developers have about the pump, motor, gearing, sensors, and any other related components can be the difference between a successful project and one with a higher probability of failure.
Fortunately, Peter van Beek, the Medical Business Development Manager at maxon, took time to address a number of questions about how the company tackles drug delivery pump projects. He speaks to several topics that are important to consider, including the types of motor assemblies used for these types of applications, the challenges involved with portable pumps, and various options to think about.
Sean Fenske: When it comes to drug delivery devices, what types of motor assemblies are being used for these applications?
Peter van Beek: There are many different pump types utilized in the delivery of drugs. Both large- and small-volume infusion pumps move the drug, feeding, or saline fluids, often via rotary or linear peristaltic pumps; driven by a DC brushed or brushless motor-gearbox-sensor assembly. Syringe pumps use a similar drive assembly arrangement that turns a lead screw-plunger assembly. Another pump type, ambulatory pumps, are smaller mobile pumps capable of running off battery or wall power. As such, they use smaller, DC motor-gear-sensor assemblies engineered to run at peak efficiencies and have long running lifetimes. Hormone (insulin) pumps run on batteries as well and need to be as small, efficient, and lightweight as possible, as they are worn daily on the body. Generally, an insulin pump drive assembly has a diameter of 8-10mm or less and consists of a DC motor-gearbox-sensor assembly that drives a lead screw-syringe-plunger.
Smaller and smaller pump designs have continued to push the physical dimensions of the individual drive components and how these components are assembled to each other. maxon can easily integrate components into a custom design (either in-line or U-shaped—motor and gearbox next to each other, in parallel).
Lifetime expectations for a particular pump design dictate whether a DC brushed or brushless motor is utilized. A DC brushless motor provides a far superior lifetime.
"If you can imagine it, maxon can build it.”
Lifetime expectations for a particular pump design dictate whether a DC brushed or brushless motor is utilized. A DC brushless motor provides a much longer lifetime.
Fenske: What are the significant challenges involving drug delivery devices used on a patient (such as a portable pump) and how is maxon addressing them?
van Beek: maxon’s ironless core DC brushed and brushless motors were originally developed for cordless shavers in the 1960s with a design goal of providing the maximum run time between battery recharging. The ironless core motor design greatly surpasses iron-core designs and simply provides the highest efficiency possible from a DC motor, making it a preferred motor for pump designs using a battery. Combine this motor with maxon’s UP (ultra performance) planetary gearbox with one to four stage designs all having efficiencies greater than 90% and you have a winning drive assembly.
Considerable R&D has been spent by major pump manufacturers to develop disposable drug pumps or “patch pumps.” This portable battery-powered pump is thrown away after it has delivered its drug payload, which can be over several days. These new pumps are challenging traditional dedicated long-lasting pumping approaches, which are costly, take years to engineer and qualify, and are difficult to bring to market. These pump designs that are adhered to the body demand the lowest possible motor assembly costs, smallest size, lightest weight, and highest efficiency. A huge challenge for these pump designs is finding a low-cost drive assembly that provides the required validated and reliable quality for the delivery of the life-sustaining drug. maxon is exploring alternative motor designs that use less expensive disposable components and novel ways of automating construction to reduce costs.
Fenske: As the delivery devices for drugs become smaller, are you, in turn, seeing requests for smaller drive assemblies for these products?
van Beek: Yes. For many years, maxon has been making brushless and brushed motors as small as 4mm in diameter but also with diameter steps of 6, 8, 9.2, 10, 12mm, etc. These steps go all the way up to 90mm.
Fenske: How are drug delivery motors being powered and does that limit the size the entire assembly can be? What are the challenges here?
van Beek: Depending upon the pump type, different power sources are used—wall power, batteries, or both. With modern battery technologies, the size of the pump is not limited by the battery. Pole-mounted infusion pumps are larger in design due to the large amount of mechanical hardware packed in the box and redundant power source capabilities.
maxon strives and achieves the highest efficiency and longest life motor assemblies possible with the use of the highest quality subcomponents and ironless core design (lower inductance winding in comparison to iron core designs). Additionally, the ironless core motor design provides the added benefits of longer brush life, low EMI emissions (less disturbance of surrounding tightly packed electronics in proximity to the drive assembly), and no preferred rotor position (no detent).
Fenske: Is maxon capable of developing an entire pump system or just providing drive assembly components and control electronics? What additional inputs can maxon provide to improve the overall design?
van Beek: Some customers only want to purchase a high-quality servo drive assembly, which is incorporated into their larger design. maxon is happy to accommodate this approach or provide a larger mechatronic subassembly part of the pump. It’s entirely up to them.
maxon has a 60-year history of engineering DC brushed and brushless motors, gears, sensors, and drive electronics into complex drive assemblies for some of the world’s most demanding applications. This same engineering talent and expertise easily translates into building complex pumping systems, such as a linear or rotary peristaltic pumps, for example. Typically, these designs incorporate maxon motor’s CIM (ceramic-injection-molded) or MIM molded components, gearing, sensors, and mold-injected and turned parts. You can be assured the quality and engineering you associate with maxon’s catalog products will also be found in your custom pump design.
During a meeting to determine the drive assembly or a weekly meeting for a complete pump project, you can count on maxon to provide additional beneficial feedback, beyond the components. For example, thermal considerations, mounting, potential customizations, dealing with radial and axial loading of the output shaft for best life outcomes, and di-electric breakdown testing might be discussed.
Fenske: What considerations should drug delivery device developers keep in mind about the motor portion?
van Beek: Due to the criticality of drug delivery and the associated risk to patients, quality must be maintained at the highest level from start to finish. This is a primary focus for maxon and something we excel at.
For example, we must make a determination of voltage range, which the battery will cycle through from fully charged to minimum voltage. The drive assembly must be capable of providing the desired speed and torque at the lowest voltage and simultaneously not provide unacceptable speed and torque at the maximum voltage condition.
At the start of the design, determination of the torque and speed for the new pumping system is one of the larger challenges for the engineering team. Sure, the design may be analyzed on paper or in models, but assumptions are always made. True characterization comes by assembling real parts and using a maxon drive assembly as an analysis tool. maxon’s ironless core design provides a linear relationship between torque & current draw. Also, voltage & speed have a linear relationship. Thus, by placing the motor into the design and simply measuring the current and voltage, the torque and speed can be determined very precisely and quickly. Once the true parameters of an unknown system are determined, the final sizing of the motor, selection of gear ratio, and approach to highest efficiency are possible. Using the motor assembly for torque and speed analysis makes this aspect of the design simple and straightforward.
Fenske: Do you have any additional comments you would like to share based on any of the topics we discussed or something you’d like to tell medical device manufacturers?
van Beek: My final thoughts relate to quality. It is highly recommended your quality and design efforts run in parallel on your path to serial production. maxon employs a project milestone approach to both design and quality, making development steps organized and understandable. Most design efforts leave quality as an afterthought and if your time to market is critical, you do not want the quality requirements to stand in the way.
Please consider maxon with our exceptional Swiss-based engineering talent and creativity, quality processes, collaborative design and quality approach to projects, and our vast historical experience with the world’s smallest drive assemblies for your next drug delivery pump or drive assembly.
Click here to find out more about maxon >>>>>