SYGNUS allows simple integration into the casting header of the IPG that CCC produces. It has helped reduce the header volume while keeping a good insulation between contacts.

For years, manufacturers of pacemakers, defibrillators, neurostimulators, and other active implantables have been feeling extraordinary pressure from shareholders and other funding sources to quickly move from prototype to design and build. As a result, many device makers have begun searching for opportunities to integrate or systemize in order to make the most of precious time and capital. In addition, for an increasing number, this search is leading straight to the header cavity where housing of the critical lead interface takes place.

Active implantables, also known collectively as implantable pulse generators, or IPGs, have been around in their most basic form since the 1950s. These small bundles of electronics, batteries, and wires, positioned within the body and used to send electrical pulses to nerves and organs, found their earliest application in the treatment of cardiac-related conditions such as bradycardia (slow heart rhythm) and tachycardia (fast, irregular heart rhythm). However, by 1960, less than a decade after their inaugural use, IPGs were also in use to deliver pain-reducing, life-improving therapies to the deep brain and spinal cord as well.

In recent years, there have been exponential advancements in the design and efficiency of IPGs, resulting in the emergence of additional use. Seeking to deliver new modalities of pain management to an aging population (nearly 28% of Americans will turn 65 in the next decade), a fresh crop of manufacturers, fueled by entrepreneurial spirit and venture capital, have been introducing breakthrough technologies for the treatment of angina, epilepsy, and even hearing loss. Once a “dumb” unit designed only to deliver, today’s IPG has evolved into a device that can, in some cases, predict seizures by sensing microvolt fluctuations in brain wave activity – and potentially stop them before they begin.

Nevertheless, as the number of new players in the IPG marketplace has grown, so too have investors’ demands for faster, less resource-intensive development of innovative devices and new therapies. The answer for some manufacturers has been to look within their designs for opportunities to systemize and integrate.
 

Top-Down Approach
One area identified by many OEMs as ideal for integration is the device header. This implantable-grade plastic or silicone enclosure at the top of the IPG is hermetically sealed to the can – the metal housing in which the electronics and battery reside – and it can make up as much as 25% of the overall device volume. All of the critical connections that drive the IPG’s functions originate in the header connector cavity – where transmission of power is through multi-channel connections – going out as signals from the battery and electronics to the lead, and ultimately out to the body. Electrical contacts inside the header ensure that the transmission of the right signals occur through the right channels on the lead, and that the seals between those contacts are isolated against both bodily fluids and electrical cross talk that may otherwise cause false positives, improper stimulation, or general malfunctioning of the device.

In the half-century or so since the introduction of the first IPG, this dual need for connecting and sealing has remained constant. However, some of the tools engineers use to meet that need have changed significantly.
 

Connection Progression
In the early days of IPGs, the setscrew was the primary method for fastening and connection. Used in series along the header, it provided both mechanical retention and electrical contact. However, as device functionality improved and the need for multiple connections grew from four, to six, to as many as 16 in some neurostimulators, the process of tightening each setscrew during the surgical process became less and less viable. While it acknowledged the continued need for a setscrew to ensure absolute retention of the lead in the device header, the medical community demanded alternatives, and several new types of contact technologies began to emerge.
 

Among the first of these to supplant the multiple setscrew setup was the Multi-Beam contact – resembling a leaf spring ribbon inside a can – which was designed, manufactured, and introduced by Medtronic and is still widely used today. Constructed of stainless steel, titanium, and MP35N, the Multi-Beam offers cost-effective electrical connectivity. However, its relatively low number of contact points (six to eight) can mean higher contact resistance, which may result in reduced battery and device service life. In addition, the Multi-Beam has inherent size limitations, and its leaf springs have linear force curves that can result in variations of insertion and extraction forces.

The Canted-coil spring, a contact technology developed around the same time as the Multi-Beam, offered designers yet another alternative to the setscrew. Designed by Bal Seal Engineering Inc., the spring was first employed in an IS-1 ring connection, but it soon evolved into a spring/housing combination that could provide a desirable weld surface. The combination, which became known as the Bal Conn, continues to be specified by many of today’s device makers, due in large part to its ability to provide very low electrical resistance in a limited space. The Bal Conn’s Platinum-Iridium spring allows for low, highly-controllable insertion and extraction forces, and its spring coils provide multi-point conductivity. While it can help conserve header real estate, the Bal Conn is best suited for challenges that cannot be met by off-the-shelf solutions.

The ImplanTac Contact Socket is a more recent IPG interconnect offering. Its manufacturer, Hypertronics, describes the design as a basket of wires that positions lengths of wire strung at an angle to the socket’s axis. This contact offers low electrical resistance and low insertion/extraction forces, but its construction limits it to a set axial length, which can be prohibitive for OEMs seeking to reduce package size or pack more contacts into the connector cavity.
 

Stuck in the Middle
Unlike their contact counterparts, the seals used to provide fluidic and dielectric isolation inside the device header have not evolved all that much. Generally, they have been (and continue to be) molded from implantable-grade silicone, a material with properties that are widely known and accepted in the implantable world. Silicone is soft and malleable, so it flows easily into and around non-uniform surfaces while retaining the ability to seal. It is also relatively inert, so it is less likely to react with the metals used to form the contacts and lead.
 

The SYGNUS system allows a simple integration into the casting header; it has a reduced size, a controlled pitch, and adjustable  numbers of contact per row.

Arriving at Integration
Traditionally, producers of IPGs have had little choice but to undergo the costly, iterative, and time-consuming job of purchasing electrical contacts and designing, creating, and testing their own isolation seals for the critical lead interface. By some industry accounts, this process can tack as much as six months onto the development of a new device.

However, a new kind of plug-and-play connector technology, slated for formal introduction this month, may make the process obsolete – at least for some smaller OEMs and startups focused on emerging therapies.

The concept behind this technology is relatively simple. First, take a proven electrical contact platform and package it with isolation seals that can guard against fluid infiltration and prevent signal leakage. Then, test the components for insertion and extraction forces, conductivity, electrical resistance, seal isolation, and other criteria, so that a manufacturer can confidently integrate the entire connector system into its device design and move closer to the ultimate goal of market introduction.

Bal Seal Engineering has developed an example of this approach, which effectively pairs seals and contacts in a pre-tested, compact, and scalable package. Marketed under the trade name SYGNUS, this solution is built around the Canted-coil spring technology and is thought to be the world’s first seal-integrated contact system.

The SYGNUS system combines the tiny springs made from Platinum-Iridium, metal housings of MP35N, and implantable-grade silicone isolation seals in a configuration that forms a dense connector stack to accommodate lead diameters ranging from 0.90mm to 3.20mm. Since a version of the seal/contact combo is engineered to the recently-ratified four-pole standard (IS-4 and DF-4) for cardiac health management devices (a proximal cap serves as the datum, and a distal cap completes the footprint), the company says SYGNUS gives manufacturers the ability to dedicate resources to therapy and function improvements, instead of component procurement or development.

“There has definitely been a growing need for this kind of solution,” says Bal Seal Business Development Manager Bill Nissim. “To some companies, especially those facing venture capital deadlines and clinical trial windows, choosing a system like [SYGNUS] provides a level of freedom that could mean the difference between success and failure. Similarly, from a patient’s perspective, it might be one of the factors that determine whether or not a breakthrough therapy ever makes it to market.”

Cardiac IPG device makers who have recently tested and adopted the new standardized seal/contact technology cite reliability, safety, and ease of implementation as primary reasons for their choice. Moreover, in a move that mirrors their CHM counterparts, designers of active implantables used in the delivery of neuromodulation therapies are now eyeing the same kind of stack solution – engineered to even smaller, more contact-dense specifications – for the very same reasons.

For now at least, this new focus on systemization – especially of the contact/seal variety – is more prevalent among small, agile manufacturers whose organizations do not afford for the vertical integration common to the industry giants. However, it may not be long before even the heavy-hitters discover the benefits of specifying pre-packaged, pre-tested connecting solutions for their devices.
 

Q&A with CCC:
With the introduction of SYGNUS, the integrated implantable seal/contact system for use in cardiac and neuromodulation devices Today’s Medical Developments caught up with a representative of CCC Medical Devices, a company that has already started using it.

In the following Q&A, CCC Business Development Manager, Oscar de Oliveira, explains his company’s decision to use the integrated seal and contact stack, and how that decision has affected technology and yield at CCC.

TMD: What does CCC Medical Devices do?
CCC: We are a medical device company offering design and manufacturing contract services, with more than 40 years of experience with implantable medical devices and systems. CCC’s customers are research institutions and medical device companies, and we design and develop devices and systems for many medical fields, including neurostimulation, heart failure, obesity, diabetes, blood pressure control, sleep apnea, patient monitoring, and many others.

TMD: What are some of the major challenges CCC faces in the development of IPGs?
CCC: The biggest challenge is to implement all the required features while minimizing the power consumption and the size of the device, and maximizing the product reliability.

TMD: Did CCC identify a need for a header connection solution that integrated seals and contacts? What was driving this need?
CCC: Neurostimulation therapies require delivering electrical pulses to the body, using leads with several electrodes as the interface. The IPG header must be able to connect the lead’s contacts to the internal circuit and it must be as small as possible in order to decrease the total volume of the device. From an electrical point of view, the header has to ensure a suitable seal between each pair of connectors. These factors led us to need a connection solution that could provide easy integration to the header, suitable sealing and small size, in order to minimize the size of the device and optimize its manufacture.

TMD: What led you to choose the SYGNUS Implantable Contact System as a possible solution?
CCC: The SYGNUS system allows a simple integration into the casting header; it has a reduced size, a controlled pitch, and an adjustable number of contacts per row. In addition, the silicone seal not only ensures electrical insulation between each pair of contact, but also helps eliminate epoxy leakage that could occur during header casting.

TMD: How does CCC use the SYGNUS system?
CCC: We pre-assemble it in one stack with the correct number of contacts and with an end cap and a connector block with setscrew for the lead mechanical fixation. Then it is welded to the device and goes through the epoxy header casting process.

TMD: How does SYGNUS solve the size challenges you described earlier?
CCC: The IPG header volume is usually 1/4 to 1/5 of the total IPG volume, so any solution that helps to reduce the IPG header will have an important impact on the IPG size. The SYGNUS system has helped us to reduce the header volume while keeping a good insulation between contacts.

TMD: As a result of using this system, what is the biggest benefit to CCC?
CCC: The biggest benefits of the use of the SYGNUS system are the IPG header size optimization, and the improvement of the assembly process and the product yield.

Bal Seal Engineering Inc.
Foothill Ranch, CA
sygnusconnects.com
balseal.com
 

CCC Medical Devices
ccc.com.uy

 

As the doors opened for IMTS 2010, opening day of the show also meant the first Industry Inspiration Day at IMTS 2010 – an invite-only luncheon – featuring opening remarks by Doug Wood, president, AMT – The Association For Manufacturing Technology. Following Wood’s remarks was a panel presentation, which offered attendees snapshots on four key manufacturing industries.

Rene van de Zande, president/CEO, Emergo Group, speaking on the medical manufacturing sector and its changes said, “There is a definite trend away from approving medical devices solely based on performance, and now more of an emphasis is on achieving a proper balance between cost and outcomes. Value for the money – not to be confused with low cost – will be the mantra moving forward, and medical device engineers and management need to keep this in mind during the device development phase.”

Discussing the automotive industry, in regards to manufacturing and the future, Ford Motor Co.’s VP of North American Manufacturing, Jim Tetreault, told the audience, “We have modernized every one of our engine and transmission plants over the past several years so that our manufacturing processes are as state of the art as our new engines and transmissions are. We have also made steady, sizeable investments in our plants to create a manufacturing systems – worldwide – that is both lean and flexible.”

Denise Bode, president/CEO, American Wind Energy Association discussed the growth the U.S. has seen in wind power together with the vast opportunities for components manufacturing as each turbine consists of more than 8,000 parts.

Allan McArtor, chairman and CEO, Airbus Americas, awed the audience with his look at where aerospace is today, and Airbus’ vision of where aerospace can head. Discussing the growth of additive layer manufacturing (ALM) and the possibilities it offers in aerospace manfuacturing and design, McArtor explained how Airbus is currently starting small, with a blended approach to this technology for components, while envisioning a move to the higher value parts.
Following the opening day luncheon was the four-and-one-half-day conference series, featuring more than 50 sessions on a range of manufacturing and production topics. Tom Grasson, associate publisher/editor in chief of the Industrial Group at GIE Media, lined up the stunning list of speakers and their topics, helping achieve a record-breaking number of pre-registrations. More than 400 individuals pre-registered to attend the conference, participating in sessions that educated them about Materials Engineering, Machining Technology & Trends, Alternative Manufacturing Processes, and much more.

Booth Snapshots
Planning and preparing for an event the size of IMTS means exhibitors typically unveil their latest products for all to see. Grand announcements and cutting-edge technology graced all four halls of McCormick place during this six-day exposition.

Revealed during IMTS at the Tornos Technologies booth was the EvoDECO – a new turning center featuring fully synchronous drives with strong acceleration/deceleration, significantly reducing cycle times for parts that require a lot of stopping. Additionally demonstrated during IMTS were the expanded lines of Almac milling machines and Esco by Tornos coil-fed turning machines.

Zoller Inc. hosted its new »pom« – short for »process-oriented-measuring« – product series for the first time at IMTS 2010. With »pom«, a new type of inspection machine has been designed especially for use in the tool manufacturing industry as well as grinding and sharpening companies. »pom« machines are equipped with special functionalities required i.e. for the production of milling cutters or drills and used directly next to the CNC machine. Developed for sample inspection and quick tool checks, »pom« machines are deliberately built small and compact and can easily fit in any production environment.

Mike and Geoff Howe, from Howe and Howe Technologies, airing on the Discovery Channel, graced the Flow International Corp. booth – meeting fans, signing autographs, and describing how their Flow waterjet enables them to develop some of the most versatile and advanced rescue and military vehicles. As a highlight to Howe and Howe’s appearance, a personal all terrain vehicle, developed for the consumer while having the appearance of a one-man open military tank, was unveiled.

Toolmex Corp. promoted a new generation of high performance slant bed lathes – the FTM700 and FTM1000 – which are not only larger in size, but that offer greater capabilities to the user, including the ability to handle heavier parts and multiple machining operations in a larger work envelope. A unique feature of the FTM series is that there is no loss of machining diameters by cross slide. Unlike other lathes that lose up to 20% on their diameter swing over cross slide, the FTM700 and FTM1000 maintain their diameter swing, allowing users to turn, mill, drill, thread, tap, and bore on a single lathe.

Specializing in the development and manufacturing of ultra-precision turning machines, Hembrug Machine Tools demonstrated machining techniques on the Mikroturn 300 Baseline slant bed horizontal – the first time Hembrug displayed a machine at IMTS or at an U.S. trade show. Offering superior finish of components, dimensional and form accuracies are held to 2µm or less, with achievable surface finishes as low as 0.1µm. The 300 Baseline has a 12" swing and is offered with a Fanuc 0i control system that has axis resolutions of 0.1µm.

Ganesh Machinery Inc. unveiled the Cyclone-52 TTMY dual spindle, dual turret lathe, which combines both turning and milling operations for complete part processing. Both the main- and sub-spindles use dead-length collets for part transfer and machining efficiency, including all radial, end working, and Y-axis live tooling working on both the front and back of the part while a dual 16-station live tool turret accommodates a total of 32 tools.

An expanded range of multi-material tools – including the addition of numerous thread cutting and thread forming taps – were highlights at the Precision Dormer booth. Carrying the brand name Spectrum, product introductions targeted the growing requirement for versatile cutting tools that offer high performance across a range of engineering materials. The Spectrum line is designed to promote a continuous production process, with all spiral flute Spectrum taps featuring a three radii flute profile with a constant rake angle – facilitating the creation and subsequent evacuation of narrow, regular chips, resulting in negligible chip congestion.

Demonstrations of the thermal drilling process, at the Formdrill U.S.A. booth, acquainted visitors with this new-to-North America process. Considered new to North American manufacturing, thermal drilling is widely used by fabricators and small machine shops throughout Europe. Demonstrations on a small drill press, in the Formdrill booth, highlighted the ease of perforating metal using friction and how one main benefit of this process is that material that normally would be cut using the conventional drilling process, is now pushed through a bushing that triples the material thickness.

Marking metals, plastics, glass, or paper is easily achieved with the Lasit U.S.A. Inc. CompactMark 2010 Laser Marking System – with built-in automation. Demonstrated during IMTS 2010, the CompactMark 2010 features up to eight motors in one machine for marking cylindrical parts, measurement rings, tapered probes, endoscopic rods, plastic handles, trays of varying parts, and the inside and ends of objects. Up to 32 characters can be marked and read with vision on a screw as small as an eyeglass screw.

Offering numerous advantages over the design of tradition collet chucks, Quick-Grip CNC Collet Chucks from Royal Products showed advanced technology to attendees at IMTS. What intrigued attendees most was the demonstration of how the collet is installed. A special installation tool compresses the rear end of the collet so that it can be inserted. Upon expansion, the collet locks into place via a hook and groove arrangement.

MMK Matumoto Corp. introduced the DEAT70 rotary table that integrates MMK’s Ott worm gear with a direct drive table. Completely submersible for EDM work and a true A/B axis table, the DEAT70 features a small footprint, which allows it to be used on smaller EDM machines – typically with no modifications to the EDM tank required.

Model B380 Deep Hole Drilling machine from Unisig, drills a 2.6" (65mm) diameter hole form solid or a 3.9" (100mm) diameter hole using trepan or counter-boring tooling, up to 157.5" (4m) deep. Demonstrated to attendees, the latest in deep hole drilling tooling showed how the B380 uses counter-rotational drilling to achieve 0.001" to 0.003" variations from the centerline of the hole being drilled per 1ft of drilling depth.

Although this recap does not come close to encompassing all the technology that the nearly 1,200 exhibitors displayed during IMTS, we hope it provides a quick snapshot at the technological advancement the manufacturing world is offering – and the growth we all see in this always-important segment to the U.S. and the world.

Material selection and coatings are two important factors to consider in dealing with friction when designing pass-through seals for endoscopic trocars. Engineers at Minnesota Rubber and Plastics (MRP) state that specifying the correct material and coating can reduce friction in these applications by as much as 90%.

The design of these seals is developing into a science of its own with friction playing a major role. Friction in these pass-through seals is extraordinarily complex. The amount of force it takes to slide one surface past another is affected by many variables influencing the surgeon’s skill and quality of the procedure.

Some of the variables that have a profound impact on friction, and those that MR&P deals with in designing pass through seals for the medical community, include the lubrication state, material modulus, surface finish, temperature, geometry of the part, and direction of the relative forces.

Surgical instrument insertion and retraction through a seal must feel smooth and easy. The more the material grabs the shaft of the instrument, the more force it will take to manipulate the instrument.

Quantifying seal friction is measured as frictional force (pounds) and is important in designing the highest quality trocar seal. Frictional force is directly related to the coefficient of friction (COF) of the material. For the most part, COF (measured using ASTM D1894 test) is what the engineers at MR&P use for comparisons as it is a sealing system measurement rather than a measurement of the property of the material.

When moving a surgical instrument or cannula through a trocar seal, the inertia that it takes to start moving is different from the inertia that it takes to stay moving. This is called the static (starting) COF and the dynamic (moving) COF. This difference will vary tremendously by material, application, and most of all, the lubrication state and/or coating, and is a central element of the feel of a trocar.

“Contrary to most thinking, sliding a rod (cannula) through a seal is never smooth,” states Ted Ahrenholtz of Minnesota Rubber and Plastics. “While it may feel smooth, in reality it is not. There is always a stick/slip force that is present where the seal flexes to accommodate the cannula’s movement, and then rebounds back to a stable state. In general, the smaller the difference between the static and dynamic COF, the smoother the inertia feels. The best seal design and the most appropriate material formulation will minimize this stick/slip phenomena. However, it is important to note that some degree of friction will always be present in all seals used for this purpose.”

Surface Finishes, Coatings
However, surface finishes and coatings on the trocar seal material can substantially reduce the coefficient of friction – the smoother the surface, the greater the COF. A matte finish can greatly reduce the amount of friction on a very smooth surface. However, maximum friction reduction is achieved with the correct coatings applied to the material surface. Depending on the substrate and its application, PTFE, parylene, chlorination, and MR&P’s proprietary processes can reduce friction by as much as 90%.
 

Doctors, hospitals, and individuals depend on the highest quality hypodermic needles to administer medicines and draw fluids. Unfortunately, 100% visual and/or water leak test inspection of the needle tubing or finished product for microscopic cracks or defects is nearly impossible. A hypodermic needle manufacturer has integrated automated eddy current testing solutions from Criterion NDT into their production lines to inspect 100% of their material for cracks and defects.

Medical grade hypodermic needles are available in numerous diameters and wall thicknesses. A hypodermic needle manufacturer wanted to detect through-wall cracks down to 0.100" x 0.004" (2.5mm x 0.1mm), in needles down to 0.011" (0.28mm) in diameter. The manufacturer’s process commences with the forming and welding of medical grade stainless steel strip, where tubing is drawn through forming dies and annealed, repeating this process until the desired diameter is achieved. The manufacturer wanted to ensure the quality of the tubing immediately prior to the needle cutting process.

Eddy current testing is very well suited for finding defects in metallic tubing and wire used for medical applications. As an example, a heart valve manufacturer employs eddy current to test the wire used in their heart valves. Manufacturers also use eddy current testing to find cracks and flaws in metal components such as bearings, gears, and shafts. Because eddy current testing is sensitive to the structure of the material, other applications may include detection of proper material hardness, case depth, and alloy. the solution In eddy current testing, an induction of an electromagnetic field into a metallic object, by way of an electrical coil, is the first step. The flow generated by the eddy currents in the metal will vary depending on the microstructure of test material. A crack or a flaw in an object will physically affect an eddy current, causing it to have to flow around the defect. The eddy current coil is sensitive to the magnetic field produced by the eddy current flow in the metal, and information related to changes in this field are processed by the eddy current instrument. The flaw detection thresholds are set based upon the enduser’s established quality requirements.

For the hypodermic needle application, the manufacturer installed eddy current testing systems just prior to the needle cutting process, where defective materials could easily be cut out in-line, in real-time. This allows the medical tubing to be 100% tested at production line speeds with the test designed to find defects in both the weld and base material.

The complete testing solution consists of an eddy current encircling coil and an eddy current test instrument, interfaced with the production line cutting/sorting mechanism. The tubing passes through the eddy current coil, which contains two separate windings, and in order to optimize flaw detection, the encircling coil is precision designed to ensure a close fit with the material.

The eddy current test instrument drives the windings in the coil with one or more test frequencies selected specifically for the material being tested. The eddy current instrument then monitors the received eddy current signal variations to determine whether a defect is present based on alarm limits that were previously established around a known good product’s test data. If a defect is present, the industrial I/O controller within the instrument sends a signal to a PLC in the cutting/sorting mechanism to remove, automatically, the defective material from the production line.

A typical eddy current flaw signals the user and the InSite eddy current instrument allows the manufacturing engineer or the operator (utilizing password protected limited access settings) to adjust the detection threshold to set the flaw detection criteria and eliminate false alarm readings. Besides providing a good/bad sorting process, the data can be stored and used to identify process control issues and significantly reduce scrap rates. By installing testing equipment at various stages in the manufacturing line, each process can be easily monitored. In addition, Criterion NDT’s Zetec InSite eddy current instruments are capable of testing tubing at various line rates.

As the hypodermic needle manufacturing process runs continuously, the eddy current encircling coils are subjected to extreme wear conditions. To provide maximum durability and life, Criterion NDT uses TTZ (Trans-Toughened Zirconia) ceramic coil inserts. The hardness of the TTZ significantly extends the life of the coils, protecting the electrical windings from wear and damage caused by the cutting action of the small diameter tubing, as well as protection from any burrs and snags that may occasionally be present.

Tube manufacturing processes can introduce permeability variations, which influence the test results by adding a significant amount of consistent electromagnetic noise and local areas of residual magnetism, which can result in large, intermittent flaw-like responses. Small permanent magnets can be installed in the encircling coil to realign the magnetic domains within the material as it passes through the coil, greatly attenuating any permeability variation and residual magnetism noise.

One hundred percent in-line, real-time eddy current inspection can help ensure the overall quality of the product without sacrificing production throughput. It also helps manufacturers identify problems early on in the production process, helping with continual process improvements while reducing scrap and saving money by not adding value to sub-standard materials. Eddy current testing is a green technology, not requiring the use of chemicals or dyes, and allows the capturing of production line statistical data. Eddy current testers can also be used to validate heat treat processes and material structure conditions.

Criterion NDT
Auburn, WA
criterionndt.com