The Path to Reliable Fluid Dispensing in Cardiac Implants

Overview

Since the 1950s, people with irregular heartbeats or other heart conditions turned to cardiac implants like pacemakers and implantable cardioverter defibrillators (ICDs) to save or improve their quality of life. These life-saving devices have evolved over the years, first as wearables and were eventually implantable. As technology has improved, there is a growing trend of these cardiac implants getting smaller in size to make them the more comfortable for patients and less invasive when surgically implanted.

In this article, we will describe the many fluid dispensing applications required to manufacture these devices and the importance of accuracy and reliability, ever critical in the life sciences industry.

Fluids Used

Cardiac implants consist of two parts: the implantable pulse generator, or housing, and the leads.

Inside the generator are electronics that record the electrical activity of a heart, which a cardiologist can later analyze, and a lithium battery to power the device, which lasts roughly 5-10 years.

The leads are insulated conductors that deliver electronic pulses or shocks when a patient’s natural pacemaker, the sinus node (SA node), is malfunctioning. Manufacturers typically use a variety of fluids, including adhesives, lubricants, silicones, and UV masking, when making cardiac implants.

Application Requirements

This life-saving technology, much like other implantable devices, face heavy regulations to guarantee patient safety and reduce complications post-surgery. For example, in the U.S. it’s the FDA and in Europe it’s the UMDR. For implantable devices, these regulations include trials on many patients and following up a year after surgery, taking time to gather information.

This is one reason why some manufacturers still use manual technology to produce cardiac implants since they would have to undergo testing and have the new technologies pass, taking time away from making the products. It’s also important to get in-country data for clinical data so if the device will be used in the U.S., it needs to be tested in the U.S.

These regulations in place help determine if the device is functioning properly in terms of lead function, battery life, and programming. The goal is to help patients maintain a normal heart rate and for the technology to last roughly 10-20 years since removal of these devices gets harder overtime once the leads fuse to the walls of the heart and you risk lacerating the superior vena cava, the right atrium, or right ventricle.

As many as one in every 20 patients will get a bacterial infection within 3 years of undergoing surgery. The infection could be caused by the surgery or an issue with the pacemaker. One way to prevent these symptoms in patients is to make sure the pacemakers are properly built from the beginning and that’s where precision fluid dispensing comes in.

Carefully making each part of the pacemaker, such as insulating the leads or molding of the pacemaker housing and assembling those parts into the final product is key to creating properly functioning devices that pass these regulations.

The technologies used to assemble pacemakers must operate consistently and with repeatable results.

Common fluid dispensing applications in cardiac implants include:

• Insulating leads with silicone
• Lubricating titanium before it is pressed into molds
• Bonding septums to circular header cavities
• Insulating electrical components with silicone
• Coating the pulse generator with silicone
• Protecting PCBs with UV masking material

Fluid Dispensing Solutions

Manual Fluid Dispensing

For many cardiac implant manufacturers, handheld fluid dispensing devices are a great option for fine motor control especially when applying very viscous fluids.

Insulating Leads

One application in pacemaker and ICD assembly is insulating the leads of cardiac implants with medical-grade adhesives like Nusil silicone. Properly coating these leads is important because they take the electrical current from the pulse generator and stimulate the heart to beat in a normal rhythm. If the sealing on the leads gets damaged, they cannot send proper signals to the heart.

For this application, we recommend the HPx High-Pressure Dispensing Tool, which consistently applies viscous fluid through dispense tips as small as 0.004”. Featuring an ergonomic design that reduces hand fatigue, this is especially important when manufacturers are working on insulating at least two pacing leads per pacemaker or ICD.

The HPx works with our Ultimus I benchtop fluid dispenser for control of the dispensed amount via foot pedal and dispensing settings, such as time adjustment as fine as 0.0001 seconds. Paired with our MicroDot Dispense Tips, which range from 27-33 gauge, the system delivers repeatable micro-dispensing.

Semi-Automated Fluid Dispensing

Lubricating Titanium

Manufacturers use lubricants to coat the flat pieces of titanium before they press and form them into the housings of the pacemaker and ICD generator. The 781Mini spray valve consistently sprays lubricants on the flat pieces of titanium before pressing them into the pacemaker or ICD housing molds to avoid cracking.

Getting a proper seal reduces the likelihood of the pieces cracking as they get pressed into the molds. Most cardiac implants are roughly two inches long and about two quarters stacked in width. Working with such small parts the 781Mini allows manufacturers to reliably dispense uniform spray patterns as small as 1 mm (0.04”) wide. The small form factor also allows the valve to get close to the part and dispense exactly where it is needed.

Bonding Septum to Cavity

During pacemaker assembly, a septum needs to be inserted into each circular header cavity on the transparent device header with a medical adhesive. The septums are small, circular, flexible barriers that are placed over the openings of a pacemaker header.

These holes provide access points for surgeons to puncture with a needle to manipulate the leads during surgery or any follow up procedures. They prevent bodily fluids from entering the device, which could cause contamination.

For this application, we recommend our PICO XP jetting system. This technology is extremely precise and maintains accuracy even as temperatures rise and fall. Jetting is advantageous because it consistently dispenses onto uneven workpieces. It’s also faster than contact valves because it doesn’t require Z-axis movement, which is beneficial for manufacturers building roughly ≥ 250,000 pacemakers annually.

Pair this with our PROPlus Series automated dispensing system, which is our most advanced robot designed for precision and simplified usability. Its high-definition CCD smart camera allows manufacturers to easily see where they’re dispensing and accurately dispense even on transparent surfaces. Equipped with laser height sensing, this robot is a great option when working with delicate and small substrates.

Insulating Electrical Parts with Silicone

Another application is attaching the head of a pacemaker to the pulse generator with a medical grade silicone. This fluid works well because it’s tolerated by the human body and acts as an insulator for electrical parts. For this application, the Ultimus V high precision dispenser is recommended since it works well with silicones. This process can be automated with our PROX automated dispensing system for a complete system and a secure bracket for the syringe barrel.

It includes all the same features as the PRO/PROPlus Series but offers a larger working area of 500 mm x 500 mm to fit even more pacemaker housing parts to keep up with the growing demand. This robot uses a contactless linear motor, which lowers motor wear and tear, improving longevity and reducing maintenance requirements.

Coating the Pulse Generator

The pacemaker housing assembly, or pulse generator, is another critical step in the manufacturing process. This is where the electronic circuitry and battery are located. Manufacturers will generally use a special silicone formulation such as pyrroline to coat the outside of the pacemaker.

The pulse generator not only monitors heartbeats, but also captures data that can be remotely collected by a patient’s doctor. It is crucial for this part of the device to function properly since it is constantly monitoring and analyzing the patient’s heart rate depending on physical or physiological changes, which information then gets sent through the leads to stimulate the heart.

Protecting PCBs with UV Masking Material

Manufacturers will use UV masking to cover places they don’t want covered by a conformal coating in the final step to protect the PCB from bodily fluids. For this application we recommend the 752HF-SS high flow diaphragm valve, which provides precise, drip-free dispensing of UV coatings.

The 303 stainless steel fluid body is resistant to corrosion and provides manufacturers with a trusted dispensing solution that’s made to last. The valve also provides manufacturers with a positive shutoff for a clean dispense, ensuring that the fluid is dispensed exactly where it is needed. This can be easily mounted onto any automated dispensing system.

Impact (Why Fluid Dispensing Matters)

Pacemakers have such a positive impact on patients and ensuring these devices are functioning properly from the beginning assembly steps is ever important. With precision fluid dispensing solutions, this gives manufacturers the ability to produce high-quality cardiac implant devices with less waste and fewer rejects to save time and costs.

Conclusion

Cardiac implant manufacturers face a growing demand for pacemakers as technology improves, more information about the heart is being discovered, and an aging population with a wide variety of heart conditions increases. In turn, they have searched for the best fluid dispensing systems on the market to ensure they’re meeting and surpassing all the stringent regulations around their products and bringing their best to the market.

Frequently Asked Questions

What are cardiac implants?

The most common types of cardiac implants include pacemakers and ICDs. Pacemakers are recommended for patients whose sinoatrial node (SA node) isn’t working properly and cause the heart to beat too slow, too fast, or irregularly. The pacemaker monitors and ensures the heart beats in a normal rhythm by delivering electrical stimulation through two leads. A cardiac resynchronization therapy (CRT) is similar to a pacemaker but has three leads used for patients who have heart chambers beating out of time with each other, requiring the extra electrical stimulation.

ICDs are used for patients with recurrent tachycardia (categorized by a heart rate over 100 beats per minute outside of age and physical activity) or ventricular fibrillation, also known as arrhythmia, where the lower heart chambers contract rapidly and in an unpredictable manner. This technology jumpstarts the heart in a way by delivering an electric shock to the heart.

What fluids are used to manufacture cardiac implants?

Medical grade adhesives, lubricants, silicones, and UV masking are the most common fluids used in manufacturing cardiac implants.

What automated fluid dispensing systems are used by cardiac implant manufacturers?

Cardiac implant manufacturers use automated dispensing systems when their application requires more precision and increased production. These automated systems can easily be paired with precision fluid dispensers, which provide greater control than the typical hand syringes used in manual assembly processes. For a complete, system, manufacturers can choose from a wide variety of jet valve systems, valve systems, or syringe barrels to mount onto the robots for virtually any application.

Forward-thinking, cardiac implant manufacturers may be interested in the PICO Nexµs jetting system. This controller monitors and controls the PICO Pµlse XP jetting valves’ programming through a human machine interface (HMI) at the point of dispense.

This is the next step in automation. Its small, 24V, DIN-rail mounted construction saves valuable room on the factory floor. It’s also extremely customizable and users can operate the controller using Industrial Ethernet and protocols such as PROFINET®, EtherNet/IP™, or NX protocol via TCP/IP.

How are fluid dispensing solutions used in cardiac implant manufacturing?

Fluid dispensing systems fall into every step of the cardiac implant assembly process, including:

• Insulating leads
• Coating the pulse generator housing
• Adhering septums to the head of implants
• Insulating electrical parts
• Coating the pulse generator
• Protecting PCBs with UV masking material

Especially with all the regulations around implants that are surgically placed in a human body, it is ever important that there is precision, especially during the fluid dispensing step of the manufacturing process.

What impact does fluid dispensing have on cardiac implant manufacturing?

Fluid dispensing solutions help cardiac implant manufacturers produce high quality products. Using precise, repeatable technology, manufacturers can increase production, reduce rejects and fluid waste, and ensure they will meet and exceed industry regulations.

关于艾哈迈德·汗

Ahmed Khan 是诺信 EFD 精密流体点胶和自动化部门的全球产品经理。他为客户提供建议和解决方案，并帮助进行初始系统集成。Ahmed 拥有 13 年的流体点胶经验。他于 2013 年加入诺信 EFD，常驻英国。