Helpful Definitions and Terms

Below are some helpful definitions and terms which might be used throughout our website or company literature.

  • 3D printing
    Also known as additive manufacturing, this is the process of making three-dimensional solid objects from a digital file.  This contrasts to subtractive processes, such as the NC machining of traditional manufacturing, in which material is removed rather than being added.

    An object is made in an additive manner by depositing successive layers of material until the entire object is built.  Each layer can be visualized as a thinly sliced horizontal cross-section of the eventual object.

    It all starts with a digital or virtual design of the object you want to create, made with a 3D modeling program by using a 3D scanner to copy an existing, usually hand-sculpted object.  The 3D scanner digital copy of the object that is used as the template for 3D printing.

    From prosthetics to heart valves, the tech brings custom designs into operating rooms and doctors' offices. Hospitals and researchers are experimenting with 3D printers in hopes of printing human tissue and organs.
  • Adhesives -                                                                                                                    
    Materials used to hold two surfaces together.  An adhesive must wet the surfaces, adhere to the surfaces, develop strength after it has been applied, and remain stable.   (See below for classification on the several adhesives).

    Characteristic and Availability                                                                              
    .  Chemistries   -   Epoxies, polyurethanes, polyimides and more
    .  Form - Paste, liquid, film, pellets, tape and more
    .  Activation method - Hot melt, reactive hot melt, thermosetting, pressure sensitive, contact, and more
    .  Load-carrying capacity - Structural, semi-structural or non-structural

  • Automation - 
    Automation is the use of equipment in a system of manufacturing or other production process that needs minimal human intervention.  Automation can also be the use of a machine designed to follow a predetermined sequence of individual operations.
  • Bump Tubing - 
    Bump tubing is a tube that has different diameters at each end.  The diameter may also vary along the tube's length.  Generally, the small diameter end is inserted into the body and the larger diameter attaches to a medical device.

    The manufacturing process is similar to other extruded tubing processes, except bump tubing adds the complexity of forming and sizing more than one diameter as the part is continuously extruded.  The larger diameter is formed as the extrudate leaves the die, in the gap between the die and a cooling device.  This is achieved by controlling the internal air pressure while varying the speed at which the product is extruded.  That is, the puller speed slows while internal air pressure increases to create the larger diameter.

    The reverse brings the tube back to the small diameter.  The rate of change must be accurately controlled to maintain consistent diameters.

  • Catheters -
    Medical catheters are tubes used in healthcare to deliver medications, fluids, or gases to patients, or to drain bodily fluids such as urine.  Examples include vascular access devices or intravenous catheters, urinary catheters, and chest drainage tubes.

    Catheters are generally inserted into a body cavity, duct, or blood vessel.  They may be thin, flexible tubes called soft catheters or thicker and more inflexible catheters called hard catheters.  A catheter that may be left in the body, whether temporarily or permanently, is referred to as an indwelling catheter.

    A Ballon Catheter incorporates a small balloon that may be introduced into a canal, duct, or blood vessel and then inflated to clear an obstruction or dilate a narrowed region to drain body fluids.  Drug-coated catheters, a more recent
    innovation, are designed to deliver anti-restenosis compounds like those used in drug-eluting stents.

    A Guidewire Catheter is a wire or spring that provides extra strength and stability during catheter placement and exchange during contralaterial access (the opposite side of the body on which a particular condition exists) and in carotid
    procedures involving the two main arteries that carry blood to the head and neck.  A guidewire also aids in catheter delivery.

  • Dip Molding -
    Dip molding is any process in which a mold is dipped into a polymer for the purpose of molding a part.  This process is ideal for caps, grips, formed parts and more.  To begin the process, aluminum or steel mandrels/molds are mounted on a handling rack.  The rack is ideal for dipping in a mold-release agent to help remove a part, prior to preheating.  The mandrels are then dipped into a plastisol material for a predetermined time.  Ready parts are cured, dip-quenched and stripped off the mandrels.

  • Disposable Devices - 
    A disposable device is any medical apparatus intended for one-time or temporary use.  Medical and surgical device manufacturers worldwide produce many types of disposable devices.

    Examples include:  hypodermic needles, syringes, applicators, bandages and wraps, drug tests, exam gowns, facemarks, gloves, suction catheters, and surgical sponges.

    The primary reason for creating disposable devices is infection control.  When an item is used only once, it cannot transmit infectious agents to subsequent patients.

    One might think the most important factor in the design of single-use products is cost, but disposable medical devices require a careful balance between performance, cost, reliability, material, and shelf life.

    Plastics are often used in the manufacturing of disposables because they are relatively inexpensive and there are many different types.  In a device such as a syringe that must undergo extreme pressure, polycarbonates are used because of their strength.  PVC can also be used because of its flexibility.  Reusable devices, on the other hand, are typically made of more costly, sturdier materials such as ceramics or steel.

    Disposable-device assembly depends primarily on injection-molded plastic, assembled by bonding, gluing, ultrasonic welding or radio-frequency welding.  The high production volume of single-use devices calls for an automated assembly in clean rooms to minimize human contact.

    Unlike reusable devices, which are often sterilized at the healthcare facility, disposable devices are sterilized before leaving the manufacturing site.  The device and packaging must be designed to accommodate sterilization.

    The reprocessing of medical devices labeled for "single use" has been a standard practice in U.S. hospitals for years, because it can cut costs and reduce medical waste.  But before medical devices can be reprocessed and reused, a third-party or hospital reprocessor must comply with the same requirements that apply to original equipment manufacturers, according to FDA regulations.

  • Ethylene Oxide Sterilization -
    Ethylene Oxide (EtO or more recently EO) sterilization is the process of sterilizing medical and products that cannot withstand heat, such as electronic components, catheters, plastic packaging, and plastic containers.

    Important specifications to control in an EO process are relative humidity (RH), temperature, and pressure.  Vacuum (negative pressure, less than - psia) is pulled prior to introducing the EO process, to ensure that gas permeates the product being sterilized.

    A common sterilization cycle has several stages.  Preconditioning exposes the product to a warm, humid environment for at least 12 hours (70% RH, 55°C) to ensure the product is at a reliable temperature and humidity.  Next, a vacuum is pulled to introduce EO gas.  The product is exposed for 4 to 8 hours.  Lastly, the EO is removed by repeatedly flushing the chamber with air and pulling a vacuum.  This cycle is repeated until the EO gas is cleared out.  There is no standardized cycle for EO sterilization, which is performed at a wide range of exposure times and gas concentrations.

  • Gamma and E-beam Sterilization -
    Gamma and E-beam sterilization are radiation-based techniques.  Neither method, however, results in radioactivity.  Exposing a product to continuous gamma rays performs gamma sterilization, and E-beam sterilization uses electron beams.  E-beam is more powerful and has a shorter exposure time.  Reusable devices sterilized by these methods must undergo a "Quarterly Dose Audit" to ensure that they meet the established standards and sterilization levels.

    Sterilization through irradiation is considered efficient because it leaves no residue on the sterilized device and doesn't require a quarantine period.  The rays can penetrate dense materials and closed package products with minimal temperature increase or effect on the product material.  E-beam radiation, however, has certain limitations when penetrating dense materials or products with varying densities.

  • High-Performance Plastic Usage in Medical Devices -
    Prior to the development of high-performance plastics, many medical devices were heavier, more expensive, and ultimately less efficient than the equipment used today.  Recent plastics and polymers have improved existing technologies, helped create new medical solutions, and are on the cutting edge of future devices.

    So common are plastics in the medical industry that their presence in almost every facet of healthcare can easily go unnoticed.  Child-proof locking systems for prescription pill bottles, tamper-evident seals, prosthetic limbs, surgical gloves, MRI and X-ray machines, all rely on plastics.  Depending on the specific application, there are many different types of plastics created for medical needs.  The basic composition for these materials begins with polymers.

    Polymers are large macromolecules comprised of repeated subunits called monomers.  Monomers chemically bind to each other to create polymer chains that are either linear, branched or cross-linked.  In linear polymers, such as polyvinyl chloride (PVC), the molecular structure is a single, extended chain.  Branched polymers have extensions or "branches" attached to the molecule chain, but do not connect with separate macromolecules. Branched polymer materials tend to be stiffer than linear polymers.

    Cross-linked polymers, or network polymers, also have extensions; the difference is that these branches bond to other polymer chains.  The result is a material that is more brittle than the two other chain types, but harder, that doesn't lose its shape when heated.  Thermoset plastics are an example of a cross-linked polymer. These materials are the building blocks of high-performance plastics.

    Thermal and radiation stabilizers, tougheners, plasticizers, antistats, and catalysts are just a few additives used to optimize plastics for specific uses.

  • High-Performance Polymers -
    High-performance polymers are hard-wearing plastics with a thermal resistance >150°C.  A few examples include:
    .  PEEK - Polyetheretherketon                         .  PES - Polyethersulfon                         .  Pl - Polyimide

  • Hypodermic Needle - 
    A hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body or extract fluids from it.  They may also be used to take liquid samples from the body, for example, taking blood from a vein in venipuncture.  Large-bore hypodermic intervention is especially useful in treating catastrophic blood loss or shock.

    A hypodermic needle also provides for rapid delivery of liquids.  It is also used when the injected substance cannot be ingested orally, either because it wouldn't be absorbed, as with insulin, or because it would harm the liver.

    Hypodermic needles also serve important roles in research requiring sterile conditions.  The hypodermic needle significantly reduces contamination during inoculation of a sterile substrate in two ways.  First, its surface is extremely smooth, preventing airborne pathogens from becoming trapped between irregularities on the needle's surface, which could subsequently be transferred into the media as contaminants.  Second, the needle's point is extremely sharp, significantly reducing the diameter or the hole remaining after puncturing the membrane, which consequently prevents microbes larger than the hole from contaminating the substrate.

  • Injection Molding -
    Injection molding makes parts by injecting heated and nearly liquid material (usually plastic) into a mold where it cools and holds a required shape.

    Plastic injection molding is a manufacturing process for producing thermoplastic and thermosetting polymer materials.  It can be used to produce a variety of parts, from micro-sized components to complete medical devices.

    Simple molds can be one-part devices in which a two-part material is poured.  Parts required in high quantities and at tight tolerances are made in molds cut from tool steel and polished so that parts can be removed easily. Prototypes or noncritical parts may be formed in molds cut in aluminum to save time and test ideas.  A mold may have several cavities along with slides and screws that produce relatively complex parts.

  • Joining Materials Method -
    The joining of materials is an important technology in many manufacturing industries.  Most products, machines or structures are assembled and fastened from parts, and the joining of these parts may be achieved through rivets, seaming, clamping, soldering, brazing, welding and the use of adhesives.

    With continuing advances in the medical industry, medical devices are becoming increasingly complicated.  Such devices are usually comprised of components and materials that must be joined in some way, whether used outside the body, in the case of instruments and surgical tools, or inside the body, for diagnostic or therapeutic purposes.

    To create highly reliable devices, one must choose which joining process is appropriate at every step.  Many factors influence those choices, from production economics, to mechanical properties such as strength, vibration damping and durability, corrosion and erosion resistance, as well as the ability to correct defects.

    Joining processes are typically divided into three categories:  mechanical joining, welding, and adhesive bonding.  Medical devices are manufacturing using a a variety of materials, from metals to polymers to ceramics, and can be joined using all three methods.

    Mechanical joining is a process for joining parts through clamping or fastening using screws, bolts or rivets. Advantages of mechanical joining include versatility, ease of use, and the option to dismantle the product in cases where regular maintenance requires it.  The ability to join dissimilar materials is another benefit.  A drawback of using mechanical joining is the lack of a continuous connection between parts, because the joint is achieved through discrete points.  Also, holes created for joining are vulnerable to fractures and corrosion.

    Welding includes fusion welding, brazing and soldering, and solid-state welding.  In fusion welding, melting and solidification occur in the zone being joined.  For details and plastics, both the work pieces and the filler material experience melting.  Brazing and soldering join materials by adding a melted filler material between the joined surfaces.  Solid-state welding requires no melting of base or filler materials, because it only involves plastic deformation and diffusion.

    Adhesive bonding joins parts using bonding chemicals.  This process may be used to join polymers and polymer-matrix composites, as well as polymer-to-metal, metal-to-metal, and ceramic-to-metal.  In this method of joining, joints can withstand shear, tensile and compressive stresses, but do not have good resistance to peeling.

  • Medtech Manufacturing - 
    This has become more challenging as more functions and features are added to medical devices.  There is a growing need for smaller devices with precise, high-quality, small features made with techniques beyond those found in traditional manufacturing.  Laser processing has been filling this need.  Today, lasers routinely mark, cut, and drill various materials for the production of medical devices.

    As with most things related to human health, there are stringent requirements for materials and the methods used to process them.  Materials for which laser tools are selected tend to be of high strength, purity, and chemical resistance, often making them difficult to fabricate and process by other means.  They also run a gamut of materials, such as:

    .  Corrosion-resistance and high-strength metals, such as stainless steel and titanium; 
    .  High-strength ceramics such as zirconia and alumina;
    .  A recent class of medical-grade polymers composed of various TPUs (thermoplastic polyurethanes),    
       polycarbonates and fluoropolymers such as PTFE (teflon).

    Such materials must be extremely pure.  In addition, their manufacturing processes, such as drilling and cutting, must be as clean as possible, leaving behind minimal debris and residue to cut down on costly and time-consuming post processing.

    Laser tools in medtech manufacturing are dominated by high-average-power C0and high-pulse-energy excimer designs.  But as medical devices continue to shrink and become increasingly specialized, leading to lower production volumes, these lasers are proving unsuitable in some cases.

  • Minimally Invasive Devices-
    Minimally invasive surgery refers to surgical techniques that limit the size of incisions needed, or has a short recovery time.  When a medical device is placed within a patient during such a surgery, it is a minimally invasive device.  Many procedures involve the use of arthroscopic or laparoscopic devices, and remote-control manipulation of instruments with indirect observation through an endoscope or large display panel.  The surgery is usually carried out through the skin or through a small body cavity or anatomical opening and can involve a robot-assisted system.

  • Nitinol -
    Nitinol is a metal alloy of nickel and titanium with unique properties, including superplasticity and pseudo-elasticity and "shape memory" properties.  That means nitinol can remember its original shape and return to it when heated.  It also shows great elasticity under stress.

    Medical applications for nitinol include:

    .  Dentistry, especially in orthodontics for wires and brackets that connect the teeth.  "Sure Smile" dental braces
       are an example of its application in orthodontics.
    .  Endodontics, mainly during root canals for cleaning and shaping root canals.
    .  In colorectal surgery, the material is used in various devices for reconnecting the intestine after pathology is
    .  Stents.
    .  Orthopedic implants.
    .  Wires for marking and locating breast tumors.
    .  Tubing for a range of medical applications.

  • Nitrogen Dioxide Sterilization -
    Using nitrogen dioxide (NO2) gas for the sterilization of medical equipment offers many advantages.  NO2 sterilization is a rapid, room-temperature process performed without using a deep vacuum.  The in-house process is considered efficient and cost effective.

    NOsterilization is done in custom chambers in load volumes of 360 to 5,000 liters.  The sterilization process is similar to other gas-sterilization methods.  The chamber is evacuated to a predetermined pressure before the sterilant and humidity are introduced.  Medical devices are sterilized during a dwell period in which spores and microbes are killed, and the NO2 and humidity are removed.  Multiple injections and dwells ensure the required sterility assurance level. 

  • Paratubing - 
    Paratubing joins two or more tubes in a side-by-side formation, allowing for customization for specific medical applications.  The tubes are thermally welded or solvent-bonded longitudinally, and are used in applications in which several fluid lines are joined in one conduit, and then branch apart to different connections.  Multiple tubing configurations are possible.

  • Peristaltic Pump -
    Peristaltic pumps generate fluid flow in a tube through the use of external, rotating rollers.  These rollers are mounted on a rotor turning on an axis.  As it rotates, the rollers make contact with the outer diameter of the tubing.  The rollers then press into the tubing, which must have some flexibility, to propel the media.  As one roller rotates away from the tube, another makes contact, continuing the constant motion of the contained fluid.

    At the points of contact, the flexible tube becomes compressed and forces the media in the direction of the rollers' movement.

    Peristaltic pumps have a number of advantages over other pump designs.  For instance, the fluid within the tube is not exposed to other pump components and only makes contact with the inside of the tube.  This prevents contamination of the fluid and pump, ensuring that the pump is not damaged by the fluid or particulates within the fluid, and that the fluid remains completely pure and undamaged by pump operation. The design also minimizes cleanup.  When a tube has worn excessively, it is usually easy to remove and replace.

    Specialized peristaltic pumps are used in various medical applications.  In some cases, the pumps move blood through the patient's veins and arteries.  The action of the pump is such that it does not damage blood vessels or blood cells.  These devices assist blood flow in various surgical procedures, and medical operations, such as open-heart surgery, in which the beating heart must be stopped so the surgeon can properly place a new valve.

  • PTFE -
    Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene with numerous applications. The best known brand name of PTFE-based formula is Teflon by DuPont, which discovered the compound.  It is a strong, tough, waxy, and nonflammable synthetic resin produced by the polymerization of tetrafluoroethylene.

    PTFE is distinguished by its slippery surface, high melting point, and resistance to attack by almost all chemicals.  It is used in a variety of products, including vascular grafts used to bypass obstructed blood vessels and grafts used for dialysis access.

  • Plasma Sterilization -
    Plasma sterilization uses hydrogen peroxide (H2O2) gas plasma technology.  A common use of this method employs a chamber to draw a vacuum.  Hydrogen peroxide is then introduced and ionized by a radio-frequency field, turning the H2O2  into electrons and reactive free radicals, or ions.  When these components encounter a microbe, they take an oxygen from it, which upsets its chemistry and kills it.

    The process is usually performed at room temperature, eliminating high temperature hazards.  Plasma sterilization is considered non-toxic, as it uses harsh chemicals.  Treatment time is one minute or less. Additionally, the process offers versatility, and can sterilize almost any material and crevice.

  • Pump -
    A pump is a mechanical device that uses suctions or pressure to raise or move liquids, to compress gases, or to force air or gases into inflatable objects, such as balloon catheters.

    The most common pump, used in medicine is the external infusion pump.  This device delivers fluids into a patient's body in a controlled manner.  There are many different types of infusion pumps, used for a variety of purposes and in different environments.

    Infusion pumps may be capable of delivering fluids in large or small amounts and may be used to deliver nutrients or medications, such as insulin or other hormones, antibiotics, chemotherapy drugs, and pain relievers.  Some infusion pumps are intended for stationary use at a patient's bedside.

    Portable or wearable versions are called ambulatory infusion pumps.

    A number of commonly used infusion pumps are intended for specialized purposes.

    Patient-controlled analgesia pumps deliver pain medication.  The pump is equipped with a feature that lets patients self-administer a controlled amount of medication as needed.

    Enternal pumps deliver liquid nutrients and medications to patient's digestive tract.

    Insulin pumps typically deliver insulin to patients with diabetes.  Insulin pumps are frequently used in the home.

    Infusion pumps may be powered electrically or mechanically and operate in different ways.

    Syringe pump - fluid is held in a stretchable balloon reservoir, and pressure from the elastic walls of the balloon drives fluid delivery.

    Elastomeric pump - fluid is held in a stretchable balloon reservoir, and pressure from the elastic walls of the balloon.

    Peristaltic pump - a set of rollers pinch down on a length of flexible tubing, pushing fluid forward.

    Multi-channel pump - fluids can be delivered from multiple reservoirs at multiple rates.

  • Radiopaque Tubing -
    Tubing placement during surgical procedures is critical for many device applications.  To make the tubing visible during imaging processes, such as fluoroscopy or x-ray, radiopaque filler is added to the plastic.

  • Reinforced Tubing -
    Reinforced tubing is typically used to support access devices or as a delivery method for another device. Reinforcing the walls of plastic tubing increases its internal pressure rating, provides kink resistance, adds column strength, and increases torque transmission.  The result is stronger tubing compared to non-reinforced tubing.  Some applications that use reinforced tubing include MCI-compatible catheters, stent replacements, shafts, vascular access sheaths, and endoscopes. 

  • Rubber Molding - 
    Rubber molding is a process that creates a useable rubber part.  Rubber products are typically made from elastomers or uncured rubber.

    An elastomer is any material with sufficient resilience or memory for returning to its original shape in response to pressure or distortions.  A wide variety of elastomers and rubber can be derived from natural sources, but are usually synthetic, produced through highly controlled chemical processes.  In tasks that require materials to stretch and revert to their original shape, rubber work is about the best.

    As another molding method, rubber molding injects a block of rubber into a metal cavity to create parts.  The mold is then heated to activate a chemical reaction that will retain the shape of the mold.  While there are method variations, the majority of rubber manufacturers use three types of heat and pressure for rubber molding.  Those molding methods include rubber injection, compression, and transfer.
  • Seals - 
    Seals, important components in many medical devices, are used to isolate and sometimes transmit fluids and gases.  They are also occasionally used to provide structural support for other components of the device.

    There are three basic seal designs:

    Status seal applications, in which there is no movement and are the most common, include preventing fluids and drugs from escaping into or out of a medical device.  Static seals range from basic O-rings to complex shapes and can be found in medical devices ranging from pumps and blood separators to oxygen concentrators.

    An example of a reciprocating seal, one with linear motion, is found in endoscopes, devices used in minimally invasive surgery.  These trocar seals allow the insertion and manipulation of surgical instruments in procedures ranging from hernia repairs to complex cardiac procedures.

    Rotary seals and the commonly used O-rings, seal around rotating shafts.  They let a spinning shaft pass through the inside dimension of the O-ring.  Motorized systems, such as scanning devices, require rotary seals. In these applications the important consideration is heat from friction where the rotating component meets the seal material.

  • Silicone Molding -
    Injection molding with liquid silicone rubber (LSR) is a process capable of producing durable parts in high volume.

    LSR molding is a thermoset process that mixes two components that are heat-cured in the mold using a platinum catalyst.  An injection-molding process is used similar to conventional plastic injection molding, but the material delivery system is cooled while the mold is heated.

    LSR parts are considered strong and elastic with exceptional thermal, chemical, and electrical resistance.  Their physical properties also maintain at severe temperatures and withstand sterilization.

    Additionally,  the parts are biocompatible and work well for products that come in contact with human tissue.

  • Steam Sterilization - 
    Steam sterilization is considered a simple and effective decontamination method.  In steam sterilization, products are exposed to saturated steam at temperatures of 121°C to 134°C.  Products are placed in a pressure chamber called an autoclave and heated with saturated steam at about 30 psi to kill spores and microorganisms.

    Steam sterilization's high temperatures mean it cannot be used for many materials.  A quarantine and down-time period is also required after sterilization as packages must dry completely before being removed from the autoclave to prevent contamination.  Once removed, they must be allowed to cool to room temperature, which usually takes several hours.

    To be considered effective, it is critical that the steam entirely covers all device surfaces.  Many autoclaves have built-in meters and catalogers to display temperatures and pressures to help achieve optimal conditions. Biological indicators and indicator tape also help gauge performance.  The tape is placed inside and outside of the sterilized packages, and bioindicator devices release spores inside the autoclave.  The spores are incubated for about 24 hours and then their growth rate is measured.  If the spores have been destroyed, the sterilization process is deemed successful.

  • Sterilization - 
    Sterilization refers to any process that eliminates (removes) or kills all forms or microbial life, including transmissible agents (such as fungi, bacteria, viruses, and spore forms) present in a specified region, such as on a surface, in a volume of fluid, medication, or in a compound such as biological culture media.

    Sterilization is accomplished with one or more of the following:  Heat, chemicals, irradiation, high pressure, and filtration.  Sterilization is distinct from disinfection, sanitization, and pasteurization in that sterilization kills or inactivates all forms of life.

  • Syringe - 
    A syringe is a pump consisting of a sliding plunger that fits tightly in a tube.  The plunger can be pulled and pushed inside the precise cylindrical tube, or barrel, letting the syringe draw in or expel a liquid or gas through an orifice at the open end of the tube.  Pressure is used to operate a syringe.  It is usually fitted with a hypodermic needle, nozzle, or tubing to help direct the flow into and out of the barrel.  Plastic and disposable syringes are often used to administer medications.

  • Tubing Connectors
    Tubing connectors for medical applications come in an almost endless variety, but the recent thrust in their design is to prevent accidental connections.  For instance, by one estimate a hospital room could have nine different fluids in use, making the possibility of a misconnection too high.

    That makes it important to have a simple and repeatable process for selecting the best connector.  The process requires an analysis of the application to ensure connectors will be compatible with the physical, chemical, and biological environment, and be easy to use as well as help prevent misconnections.  

  • Validation and Testing - 
    Validation and testing is the process of making sure a medical device meets all of the engineering requirements that make up its product requirements.  Developers must also track all the data generated from bench-top, in-tissue, animal and human testing.

    All medical devices, from simple Class I products to complex Class III devices, must be tested against all product requirements to verify that they meet engineering specifications and are validated to meet product specifications.

    During an FDA audit, the device developer must be able to demonstrate that all reasonable tests were done to lower the risks associated with the device.

  • Valve - 
    A valve is a device that controls the passage of fluid through a pipe or duct, especially a device that allows movement in one direction only.  A common example of a valve in a medical contact is a replacement heart valve.

    In most cases, heart-valve replacement is an open heart operation.  This means the surgeon breaks the patient's ribs or sternum for access to the heart and to replace the damaged valve.  The new artificial (usually a prosthetic) valve is then sewn into place.  In patients too sick to undergo surgery, the valve can be replaced via catheter without opening the chest.