Medical Cables: Often Overlooked

Medical cables are as important to a medical device as the device itself. Medical device designers many times focus on the device and overlook the wire and cables that is needed for the device to perform its function. Medical cables tend to be more specialized due to the many types of uses and environments it is subjected to. The wire and cable is many times not thought of until the end of the design process, which may be too late. Knowing your medical cable limitations and the options available to you in the beginning is important especially when designing housing or specifying connectors. Some things to keep in mind when specifying wire and cable for a medical device:

• Size- With the size of devices becoming smaller many times smaller gauge wire and cable is needed. Off the shelf wire and cable usually go as small as 28AWG. Fine wire and custom cable designs are usually needed.
• Flexibility- Handheld devices and medical robots require flexible cables which can withstand repetitive flexing. Higher stranded conductors and sometimes alloys are needed to achieve this.
• Sterilization- Sterilization can be done with alcohol, steam or gamma to name a few. Cable jackets need to withstand the sterilization process.
• Bio-compatibility- Medical grade cables are needed depending on the level of contact with the patient. Bio-compatible and implantable grade compounds are available for medical devices.
• Construction- Cables sending signals, power and even gas/fluid can be constructed in on jacket. Constructions can vary from the simple wire to complex hybrid cable.
• Unique- Medical devices are all unique in regards to application, requirements and environment. You should not use an off the shelf mass produced cable designed for to meet the generic needs of a variety of industries for a specialized medical device.
  

Considering your wire and cable needs from the early stages of your product design will prevent problems down the line in regards to failures in the field, design issues and time constraints. Designing custom medical cables for your application ensures you have a medical device that will exceed performance and longevity you require.

Depending on the type of use a variety of medical grade insulation materials are available. Reusable medical cables are built to endure constant flexing and extended cycles of sterilization. Insulation may be Teflon®, TPE or silicone rubber with TPR or silicone jackets. For disposable medical cables PVC and PE are the insulation most commonly used. Discuss your application with your custom cable manufacture in order to choose the right material for your medical device.

Working with a custom wire and cable manufacture is easier than you think. Custom wire and cable engineers work with you every step of the way to determine and suggest the best materials and construction for your medical application. It's like having a wire and cable expert on your team. Cable designs are usually modified throughout the design process to accommodate changes to the device design. Many custom wire and cable manufacturers are able to produce small quantities for prototypes and clinical trials.

Silicone Ribbon and Flat Cables: More Flexibility

When you think of extremely flexible wire, silicone insulated wire comes to mind because of its flexible properties. But what about using silicone in ribbon cable? Manufactures turn to silicone ribbon cables when applications require flat cables with specialized requirements or extreme flexibility. Flat cables and ribbon cables are often used when space is a factor ribbon cables can also be easily mass terminated using

an insulation displacement connector (IDC). Ribbon cables are manufactured in a variety of materials and configurations including silicone; the most common and least expensive insulation is PVC.

Space is a luxury as devices become smaller. Manufacturers are using flat and ribbon cables for more applications.

Industries include:

Aerospace
Automation/Robotics
Medical
Industrial
Automotive
Telecommunication

These types of applications often need insulation materials other than PVC due to special requirements such as extreme temperature, low smoke, flammability, flexibility, sterilization and chemical contact. Silicone is an excellent choice for these types of requirements. Not only is silicone wire extremely flexible, it can withstand millions of flex cycles, and has good steam and chemical resistance. Silicone ribbon cables can be extruded or bonded depending on the type of termination that is used. Extruded ribbon cables have a tighter center to center tolerance than the bonded ribbon cable. When using a bonded ribbon cable, terminating with IDC is recommended. Extruded ribbon cables normally require tooling to control shape and pitch which may add to initial cost. Bonded ribbon cables normally do not have special tooling used.

Flat cables can be manufactured in a variety of constructions which may include zip cords, ribbon cables and flat cables with an outer jacket. Custom cables can also be constructed with shielded twisted pairs, overall shield, and with tubing or lumens. Custom flat cables are also available in smaller gauges which you cannot find "off the shelf".

Silicone insulated wire and cables do have their drawback. Silicone has poor abrasion resistance, which can be a critical problem for applications where the cable comes in contact with sharp objects. Higher abrasion resistant formulas are available for silicone. Consult your wire and cable manufacturer regarding your application to find out the options available to you.

To find out more about flat cable options or if silicone cables are right for your application contact Calmont for assistance with your design or request a quote. Feel free to leave a comment.

Silicone wire: Art Using Custom wire and Cable

Custom wire and cable in art? One usually doesn't think of custom cable and art. From time to time we are contacted by artists looking for custom wire and cable for their art projects which are usually in the way of sculptures. Often times the custom wire is part of the art piece. In 2007 Claude Zervas an artist in the Seattle area needed an extremely flexible wire for an electronic art piece he was working on. The flexible custom wires needed to be placed in a way to be aesthetically pleasing and not to take away from the art piece as the wire becomes a part of the art.

"Since the wire is often exposed and becomes a formal part of the sculpture it needs to have certain physical properties such as color and flexibility. The high flex silicone insulated wire is perfect since it resists kinking and drapes like string or rope" says Claude.

His challenge was "off the shelf" wire was too stiff and could not be draped and arranged properly. The wire Claude chose is a silicone insulated wire with a high strand count conductor. This is an extremely flexible wire which was easy to incorporate into the art piece. Silicone insulation is used in a variety of industries and applications requiring super flexible wire, high voltage or high temperature.

The silicone wire was used in a sculpture commissioned by the King County Arts Commission for the exhibition hall at the Brightwater Treatment Facility (pictured on left). Happy with the performance and look of the wire, he has been using the silicone wire for other art pieces as well.

The photos below illustrate the layout and a close up of Claude's sculpture. The silicone wire plays a part in the design and function of the art piece.

"Diatomoton 5" The layout A closer look at Diatomoton 5

Here's a video of Diatomoton 5 in action:

About Claude

Claude Zervas' artwork uses technology and a variety of media to explore representation of landscape, social ecology, and memory. He creates 2D, 3D, and time-based work using video or custom computer programs. He has stated, “I grew up in a rural part of Whatcom County and I have been greatly influenced by the physical landscape, the social topology, and the transformation of this region. I am interested in how the idea of place evokes emotion, the way emotion affects memory and how memory in turn affects perception.”

After attending art school at Western Washington University Zervas fell into a career as a software engineer, eventually returning to art full-time. He leverages many of the skills acquired from his engineering experience to produce his art. Click here to see more examples of Claude's art.

If you have questions or an application requiring custom wire or cable contact Calmont for assistance. Please feel free to comment or share this article.

D5 from Claude Zervas on Vimeo.

Silicone Wire- Popular Applications of Silicone Insulated Wire and Cable

Silicone insulated wire is a popular choice for a variety of industries due to its operating temperature range, extreme flexibility, and voltage properties. Silicone wire and cable compounds are available in special grades and formulas are available for specific requirements such as, medical grade/implantable, low smoke/halogen-free, increased resistance to abrasion , flame retardant and more.

Silicone wire advantages include:

• Service temperatures from –50 to +200 °C
• Special grades are available for use in a temperature range from –90 to +300 °C
• Excellent aging resistance, even under extreme conditions
• High resistance to many different chemical substances
• Outstanding electrical properties
• Extreme flexibility

Aerospace

Aerospace and space applications often require low smoke halogen-free wire and cable. Silicone insulated cable can be manufactured with low smoke halogen-free grades. Low smoke halogen-free silicone cables offer several advantages over conventional cable products:

• Silicone does not emit any corrosive gases.
• Flame resistance - Ensures reduced flame propagation.
• Halogen-free cables generate little smoke, ensuring clear visibility during fires.

Commonly used Mil-Specs for silicone wire, is the MIL-W-16878

• MIL-W-16878/7 Wire, Silicone Insulated, 200°C, 600 Volts.
• MIL-W-16878/8 Wire, Silicone Insulated, 200°C, 1000 Volts.
• MIL-W-16878/29 Wire, Silicone Insulated, 150°C, 600 Volts.
• MIL-W-16878/30 Wire, Silicone Insulated, 150°C, 1000 Volts.
• MIL-W-16878/31 Wire, Silicone Insulated, 150°C, 1000 Volts, Glass Braid, Abrasion Resistant.
• MIL-W-16878/32 Wire, Silicone Insulated, 200°C, 1000 Volts, Glass Braid, Abrasion Resistant.

Other Mil-Specs using silicone insulated wires with FEP Jacket include MIL-DTL-8777, MS25471 and MS27110.

Medical Applications

Medical device manufactures use silicone insulated wire and cable because can be used in an autoclave, its chemical resistance and ultra flexible nature. Silicone is widely used in applications that include medical robotics, implantable, sensors and handheld devices just to name a few. Silicone wire is also manufactured for medical tubing and is typically used in applications such as catheters, drains, feeding tubes, and peristaltic pumps. Manufacturers considering silicone for these types of applications can choose from special grades that meet stringent health agency requirements.

Automation and Ribbon Cables

Typical ribbon cables are not designed for repetitive flexing. These cables are generally made of PVC which is brittle and not resistant to harsh chemicals. For applications in the automation and robotics industries a cable designed specifically for hi flex applications is needed. Silicone ribbon cables can withstand millions of flex cycles and can be extruded or bonded from as little as two conductors to over twenty and can be manufactured up to 40AWG. Applications such as multi-axis motion systems, robotic equipment, linear motor stages and packaging equipment all require flexible flat cable designed to achieve reliable performance. Silicone ribbon cables are also used in static installations where a flexible cable is required.

Automotive

temperatures, tight spaces, and contact with fluid and chemicals. This type of environment is perfect for silicone wire and cables. Silicone insulated wire is normally used in the automotive industry for ignition, battery and spark plug wire. Custom silicone cables can be manufactured to improve the engine's performance. High performance options for ignition wires can include EMI suppression, Kevlar strength members, fiberglass braid, nickel alloy conductors.

There are many applications suited for silicone wire and cable. This article only named a few. If you would like to discuss your application or have questions, please contact Calmont. Feel free to leave a comment or share this article. To find out more about silicone insulation visit our silicone page or our Insulation and jacket materials page.

Custom wire and cable: Reducing your cost.

With custom cable it is not uncommon to hear “Copper prices just dropped, why didn’t my cable price go down?” Copper prices are a major factor affecting custom wire and cable prices but not the sole factor. Custom cable is normally made to order and many times in smaller quantities which is affected by the prices of materials at the time of ordering. “Off the shelf” commodity wire is usually made continuously and in large volumes which absorb day to day cost fluctuations of copper/metals, compounds and labor/set up keeping the price more stable.

Here are just a few factors which affect the prices of custom wire and cable products

Petroleum prices- Which can range from transport and freight costs to the actual compounds which are made from petroleum products.beside copper:

• Material shortages- An example is the fluoropolymer (FEP), earlier this year due to the earthquake in Japan affected production for Daikin and DuPont which are the only manufacturers of fluoropolymers in the world today. In addition with China cutting back on their fluorospar exports which happened at the same time resulted in an increase of 20-30% for the compounds.


• Material minimums- Custom cable designs sometimes use conductors and compounds which are not commonly used and are subject to minimum buys which are factored into the per foot price of the cable.
• Set up- Setting up equipment takes time and material, the higher the volume the less the set up costs affect final price.

There are ways to help keep your cost down, for example:

• Plan ahead – Placing blanket orders, scheduling orders over multiple shipments over time. Buying higher volumes helps absorb minimums by amortizing material, set up and labor costs. Sometimes the overall cost for ordering 1000 feet is less than ordering 200- 500 feet. Ask for price breaks to evaluate your options.

• Request samples – Custom wire is usually specialized to the design however you can check to see if your manufacture has a similar item they can sample you. This is helpful when you need prototype of proof of concept quantities. Many custom cable manufacturers have sample stock and overruns available which may be similar to what you need.

• Wait for it- If you time to wait, ask your cable manufacture if they have any upcoming jobs using the same material. Running your order along with another may save you on set up costs and/or minimums. It's a long shot, but can be done if your material is a more common one.

• Substitutions- Ask what is driving the price. If a material minimum is involved, find out if there is a substitute material which may be readily available you can use. Sometimes just changing the plating or strand count can make the difference.

Custom Cable-High Performance Custom Wire and Cable

What makes a wire or cable a custom wire or cable? One would think it would have to be an elaborate cable design, but in reality something as simple as a unique color or printing can make the cable become a custom cable.

Custom wire and cable is not readily available or stocked by distributors or manufacturers. Simply put, custom wire and cable is anything that is made to order specifically for a customer. Hypothetically, let's say you have a commodity cable that you use regularly but now your product design has changed and you need one or two more conductors. You check with your distributor and the manufacture doesn't offer that construction. You now need to turn to a custom wire and cable manufacturer which is set up to run special construction cable with little or no minimums

.Yes you will pay a little higher per foot than you do with the commodity wire however, you get exactly what you need and the performance you require. Prices between custom and commodity cable can't be compared as the construction and materials are different and the quantity produced are much lower with the custom cable. In the end it's all about having choices available to make a better product.

A few benefits of using custom wire and cable include:

• Engineered specifically for your application
  
• Custom configurations
• Custom colors and/or printing
• Improved performance

You have choices! When having a custom wire or cable designed you a wide range of options to assist in building the right wire or cable for your needs. Some options include:

• Gauge sizes, smaller gauges available
• Insulation and jacket materials
• Type of shielding and construction
• 
  Conductor stranding, plating and type
  

Reverse engineering is used in situations where the origin of a cable is unknown or there is no information about the wire or cable. Engineers in most cases will carefully dissect the wire or cable taking measurements and noting the construction of conductors, cable lay, shielding, fillers and other vital information. A series of tests are performed to determine the insulation and jacket materials. At this point if a customer would like to see improvements in the cable's performance such as a more flexible cable, or higher flex life it should be mentioned to the engineers so changes can be made to the design.

So who uses custom cables? Just about every industry including medical, robotics, aerospace, music/audio, and more. Building a better mousetrap often means designing a product that will exceed its expected performance and the wire and cable needs to be considered as well.

If you do not know much about wire and cable properties, don't be alarmed. Custom cable manufacturers have engineering resources to assist you with every step of the way starting with deermining the right materials and construction based on your application and requirements.

If you have questions about custom wire and cable or a project that you need assistance with, contact Calmont for assistance. Feel free to post any questions or comments you may have. If you enjoyed this article please feel free to share it.

Medical Wire and Cable-Applications of Medical Wire

Medical wire and cable is different than wire and cable

used in other applications. Design engineers need to keep this in mind when specifying their cable. Often time custom medical cables are needed due to bio-compatibility, sterilization and possibly smaller sized device requirements.

When specifying a medical cable one needs to keep in mind several factors such as:

• Sterilization techniques autoclave, gamma, alcohol?
• Will this be a disposable cable?
• Will the cable come in contact with the patient? Bio compatibility.
• Flexibility requirements.
• How will the device be used day to day?

Due to time constraints many times engineers will sometimes settle for a readily available off the shelf cable for prototypes or proof of concept, which is fine for the short term. When it comes to field and clinical trials a prototype should be made with wire or cable specifically designed for the application to better measure longevity and functionality. Medical cable applications fall into several categories; handheld medical devices are a large segment of medical cable applications.

Medical Hand Piece Cables

Cables for medical hand pieces must carry the power, control, sensor and data to and from the hand piece. The cable may be as simple as a two-conductor cable, providing power to a cut & cauterize scalpel or a multi-conductor power, control and sensor cable used on an orthopedic surgery device. Cables for handheld medical lasers likely contain lumens for cooling. Ablating hand piece cables can also contain lumens for irrigation and suction removal.

The design of medical hand pieces falls into two categories: re-useable and disposable. See below for information on Disposable Medical Cables and Re-useable Medical Cables.

Disposable Medical Cables

Disposable medical cables are made from the lowest cost materials that will meet the design needs of the device. Conductor cost is dictated more by the number of strands used to make the conductor. The higher the strand count the more flexible the wire becomes. A marketing trade-off is often made for disposable cables, i.e. increase stiffness can be tolerated by the need to hold cost down. 7 or 19 strand conductors can be used, where in re-useable cables the strand count can be well over 50. The use of plating is reviewed and bare copper is the most often used. Tin plating is used only to enhance solder ability. Crimping the wires is often the cheapest means of terminating the conductor. Silver plating is rarely used for disposable cables. Conductor sizes are determined by the current needs of the device.

Insulation and jacket materials are chosen by cost. Low cost materials such as Poly Vinyl Chloride (PVC) or Thermo Plastic Elastomers such as poly urethane are often used. Polyethylene can be used as insulation. Insulation and jacket thickness are determined by the voltage ratings of the signals in the cable.

Shields, when required, are usually of a spiral type rather than braid to hold the cost down. Spiral shields may lose shield effectiveness during repeated flexing, but the number of flexes for disposable cables is limited.

Jacket colors usually are chosen by the program. The need for gamma sterilization may limit the color shades available. Colors can change during gamma sterilization and are usually required to be stable for less than 10 cycles to allow for re-sterilization when repackaging is needed.

Re-useable Medical Cables.

Medical cables designed for re-useable devices have to use materials that will withstand several cycles of sterilization by alcohol based agents or autoclaves.

Conductors are made from high strand count conductors for maximum flexibility and often they are made from high strength copper alloys. The size of the conductors is determined by the current they must carry to the device. To withstand the rigors of sterilization, plating’s of tin or silver plating may be required.

Insulation must also withstand the rigors of sterilization and are often either Teflon’s such as FEP, PFA or Tefzel® or Silicone Rubber. The use of lower cost materials may be made on a case by case basis.

When shields are required, they must be made from materials resistant to many sterilization cycles and are often silver plated copper or silver plated high strength copper alloys. Shield construction is usually of a braid rather than a spiral, as spiral shields can move during flexing and compromise the shielding effectiveness.

The more popular choice for cable jackets are made from Santoprene™ TPE which is good for up to 100 cycles of autoclave, or Silicone Rubber.

Medical cable applications also include implantable, medical robotics, therapeutic devices, sensors and monitoring equipment.

To find out more or discuss your applications with medical wire and cable please contact Calmont Wire & Cable.

Please feel free to leave your comments; we would enjoy hearing from you.

Medical Cable- Applications of the Lumen in the Medical Industry

In the medical device industry a lumen is a term used to describe tubing which is typically used to transfer liquids, gases/air or even other cable components such as fiber optics and cameras. Lumens can be manufactured in a variety of configurations and incorporated inside a cable with multiple lumens (multi-lumen).

If you have been to the dentist then you have had experience with lumens. The handpiece used for air and water has lumens within the cable. The suction piece placed in your mouth is a disposable lumen. Other uses for lumens include micro-surgical instruments and pressure transducers. Cables for handheld medical lasers likely contain lumens for cooling. Ablating handpiece cables can also contain lumens for irrigation and suctioning.

Lumens are not limited to the medical cable industry. Lumens are used in many industries and are often called other names such as tubing or hose.

Other industries using lumens include:

• Industrial
• Automotive
• Instrumentation and sensors
• Automation/ robotic

As products become smaller and more compact and it is more common to see tubing and cable incorporated into one component. A few examples outside the medical industry include hi-tech hand sprayers with electronic controller in handpiece, cables with hydraulic fluid tubes, pressure transducers and air controlled switches.

Often when designing a device or equipment with tubing or lumens a custom cable solution is needed. It is important to tell your cable manufacture as much information as possible about the application and its intended use.

Key information may include:

• Used for fluid, air or other?
• Will it be pressurized?
• Type of fluid or gas?
• Flexibility requirements?
• Bio-compatibility requirements?

The more your cable manufacture knows, the better the design will meet your needs. Working with a cable manufacturer early in your design phase will help to determine tubing size, material and construction to insure your project goes smoothly from the start.

Comments are welcome! Tell us about your lumen application or challenge.

Implantable silicone lumen One of the obvious benefits for using silicone wire

Silicone wire and cable is known for being extremely flexible and resistant to high temperatures, which makes it the material of choice in a variety of applications and industries that require an extremely flexible cable. Silicone wire is also flexible in the many applications and industries that it is used in. For example, Calmont is involved in a wide spectrum of projects using silicone wire and cable ranging from medical implants, automotive ignition wires to applications where the wire was weaved into fabric and even used for art and decorative lighting.

Industries that use silicone wire include:

• Medical
• Aerospace
• Robotics and automation
• Automotive

for wire and cable is the flexibility. Silicone wire, depending on the construction can be as limp as a piece of string. This type of wire is ideal with applications where routing a wire through a tight space is required such as, box builds, equipment, robotic arms or handheld devices. Other benefits include resistance to gasoline, alcohol-glycol. The temperature range for standard silicone is -60°C to 200°C and has excellent weather-ability. The downside to silicone is it's abrasion resistance which is fair. Depending on the application this may have no impact, best uses are static installations or when the wire or cable is not subject to contact with sharp objects.

Fluorosilicone is another type which is widely used and has a significantly greater chemical resistance than silicone. It is resistant to hydrocarbon fluids (gasoline / diesel) and solvents. The temperature range varies by the grade. Most is 250C it is available up to 350C upon request. Fluorosilicone also has excellent flexibility and flame retardant properties.

Tell your wire and cable manufacturer any special requirements your application has to get the right silicone compound. There are different grades, and durometers available. Sometimes a special formula or additive may be needed to meet the requirements listed below.

A few options include:

• Medical grade
• Flame retardant
• Low smoke
• High temperature to 350°C

Silicone ribbon cables are often used in place of PVC ribbon cables when flexibility is required. Silicone ribbon cables can be extruded or manufactured using a special process to bond the conductors. The construction of the silicone ribbon cable can be from two conductors to over twenty depending on the manufacturer's capabilities.

Co-extrusion: Silicone wire to the Hula Hoop.

Choosing co-extruded silicone wire for applications that require suppression of electrical noise, corona resistance, low loss of power and extremely flexible nature is ideal. The co-extrusion process for silicone wire involves the combination of two extruders running simultaneously to produce the semi conductive silicone insulation and the silicone outer jacket. There are many applications which require this type of performance.

These applications include:

• Aerospace
• Medical
• X-Ray and MRI
• Radar systems
• Photo copiers
• Robotics

Extruding the semi-conductive insulation and the outer jacket layers of silicone at the same time insures that there is no air or any contamination particles at the joining of the two layers. The use of a semi-conductive silicone layer over the copper conductor reduces corona by filling the space around the conductor with semi-conductive silicone to remove the air. The semi-conductive material also increases the effective corona inception diameter from that of one of the strands in the conductor to a diameter slightly larger than the total conductor diameter. This results in the higher corona inception values and increase effective radius of conductor found in co-extruded silicone wires.

Features and Benefits:

• Corona, moisture and ozone resistant
• Lightweight and extremely flexible design
• Radiation resistance
• Excellent electrical characteristics
• Resistant to temperature extremes
• Lower EMI

Increased Customer Benefits:

• Reduces noise on radar
• Spots on Xerox copies
• Error spots on medical x-ray's

Built in stripes

Other uses for Co-extrusion
In 1958, The Wham-O Company had a problem: The stripe in the original Hula Hoop was painted on and was wearing off quickly after a short time of use. The Wham-O Company asked Calmont Wire & Cable's founder Bill Chilcote to find a solution to the problem. Bill seized the opportunity and developed a co-extrusion process and built the equipment to add the stripe right into the tubing, which made the stripe permanent. The stripe has evolved over the years but the fundamentals of Bill’s technology are still being used today for the Hula Hoop and many other applications in a variety of industries.