Please contact me for more information.

Kevin Wickson

01323645300  Ext 204

kev@pesl.net

By Dr. Demetri Chrysostomou, Director of Technology, PVA TePla America, Inc.

Materials used for orthopedic implants are typically inert metals/alloys, ceramics and polymers. Their surface properties are engineered to encourage osteo-integration, while surface cleanliness and sterility are critical for avoiding inflammatory responses. Indeed, for implanted medical devices, achieving and maintaining surface cleanliness at the molecular level demands careful attention and exhaustive procedures.
Plasma processing is capable of removing organic contamination at the molecular level subsequent to machining, tooling and wet chemical processing steps. Plasma cleaning acts on surfaces in a conformal fashion, not only for substrates of complex geometries but also on textured surfaces with “rough” topographies. Plasma has also been shown to increase surface bioactivity, particularly on organic tissue scaffolds.

What is plasma?
Plasma is a state of matter just as a solid, liquid or gas. Add enough energy to a gas and it becomes ionized into the plasma state. Chemically it is a highly reactive environment that is used to change the properties of surfaces without affecting the bulk material.
In PVA TePla America’s plasma systems, we generate plasma by using electrical energy. This excitation process produces a soup of chemically active species at ambient temperatures that can induce chemical reactions on the surfaces of materials that are not possible under normal conditions. The collective properties of these highly active species can be controlled and harnessed to perform various surface treatments such as precision cleaning, activation, chemical functionalizing, coating deposition etc. PVA TePla America’s expertise is in the way we control the properties of the plasma.

Precision plasma surface cleaning
Using x-ray photoelectron spectroscopy, elemental surface atomic species were measured on titanium as a function of different cleaning methods. High signals from carbon indicate high levels of organic contamination, where as high signals from titanium indicate a clean surface.

Bar chart showing relative atomic percentages of carbon and titanium as a function of different cleaning procedures. Data taken from M. Wieland, Ph.D. Thesis, (1999) Swiss Federal Institute of Technology, Zurich
From the graph above it is clear that the highest signal from titanium, and the lowest signal from surface carbon both come from the plasma treated surface. For this reason plasma is ideally used for precision cleaning titanium and Co/Cr alloys after tooling and polishing implant devices. Likewise, plasma is used to clean PEEK materials after tooling and deburring. In this case plasma has a particular advantage as a cleaning technology over wet chemical methods since solvents can cause PEEK to swell thus contaminating the bulk material

Materials used for orthopaedic implants are typically inert metals/alloys, ceramics and polymers. Their surface properties are engineered to encourage osteo-integration, while surface cleanliness and sterility are critical for avoiding inflammatory responses after implantation. Indeed, for implanted medical devices achieving and maintaining surface cleanliness at the molecular level demands careful attention and exhaustive procedures.
Plasma
Decontamination Surface chemistry
Sterilizes Promotes cell adhesion
Removes organic
residues
Removes bioburdens
Minimizes leachables
Plasma removes organic contamination at the molecular level following machining, tooling and wet chemical processing steps. The decontamination is conformal not only for substrates of complex geometries but also on textured surfaces with “rough” topographies. Plasma has also been shown to increase surface bioactivity, promoting attachment.

Plasma precision cleaning of PEEK
Polyetheretherketone (PEEK) is a preferred material for vertebral implants due to its biocompatibility, physical properties, and above all its radiolucency. It is a semi-crystalline thermoplastic and therefore prone to absorption of cleaning solvents (0.5wt.% of water by test method ISO 62). This can cause the material to swell and its bulk to become contaminated. Obvious concerns are therefore raised over the choice of cleaning method used for implantable applications (traditionally 99% DI water+1% Alconox).
Since plasma is a dry, gaseous process under low vacuum there are none of the liabilities associated with wet chemistry. After plasma cleaning PEEK the total aerobic bio-burden count (CFU/SIP) was <1 and the quantification of extractable residues by chloroform using gravimetric analysis is compared with standard cleaning methods (see graph below).

When comparing cost of ownership between plasma and chemical cleaning equipment, again plasma looks very favorable. The table below compares the most significant costs; labor and consumables.

Plasma sterilization
The increasing importance of infection control in lifescience industries is placing greater focus on sterilization technologies. New regulatory forces are generating industry specific criteria. This, coupled with the need for fast turnaround and economical sterilization methods, is defining sterilization technologies for specific market applications.
Advantages of Plasma Sterilization
Process Method
Low Temperature <55C No special building requirements
No polymer damage No licensing process gases
Non-hazardous Processes validated by DIN EN ISO 14937
Tubing up to 5m meters Low cost of ownership
Short process times Turnkey systems
No risk of corrosion Cost ~ $75 US dollars per cycle
No discoloration or embrittlement Low setup costs
The germicidal affects of plasma have been known for a long time. PVA TePla America offers a sterilization solution for in-house manufacturing, targeting implantable medical devices in orthopaedics and cardiac rhythm systems. Our Steriplas offers up to 2000 litres capacity, and TUV certified for H2O2 / plasma sterilization.

WHAT IS ABRASIVE JET MACHINING?
Abrasive Jet Machining, or AJM, is the impingement of fine abrasive particles in a high-velocity gas stream. This process is also referred to as “pencil blasting” or “micro-abrasive blasting”.
SOUNDS LIKE SANDBLASTING?

AJM differs from conventional sandblasting in that the abrasive is much finer, the nozzles are much smaller and the process parameters are precisely controlled, thereby ensuring the utmost precision in cutting action. AJM can be used to process hard, brittle materials in a large variety of applications ranging from cutting to cleaning.

For decades PESL has specialised in the field of micro abrasion technology. We offer manual, automated and custom systems as well as job shop services to accommodate a number of diverse applications.
We do free proof of process at our labs. So call us today on 01323 645300 and we will collect your samples, process them and send them back to you completely free of charge . Let us show you the benefits of using our Micro Abrasive Machines for your products.
Steve Dryden

FEATURE BENEFIT SALES ARGUMENT

 SINGLE STEP PUSH Easy and Minimal The average process is 10 minutes hands on
BUTTON PROCESS Process, Minimal time for loading and unloading samples. The control
Labour Costs is automated to push button. The system transitions
automatically through up to 64 process steps.

 A DRY CHEMICAL None of the Chemical baths of chromic acid, HCI and organic
SURFACE MODIFICATION Liabilities of wet solvents such as Hexane, Toluene, Trichloroethylene
PROCESS Chemistries. are all highly dangerous chemical’s not to mention
Plasma is a Green silanes. Their use will be subject to a stricter
Technology. regulatory landscape in the future (EPA)

No costly Plasma systems use gas and monomer bottles
Chemical Storage stored & secured behind the instrument. By contrast
Facility Required. dangerous wet chemical storage requires facilitating.

No expensive Gases are exhausted in milligram quantities and in
Chemical Disposal most cases are non polluting requiring no scrubbing
Required. or regulation. By contrast wet chemical disposal is
expensive dangerous and requires documentation.
Safer and Cleaner Far less occupational health and safety issues for
For the Operator the operator. Whereas many wet chemistries are
highly toxic carcinogens and neurotoxins. Even low
vapour exposure can cause respiratory problems
such as asthma, emphysema.

Cost Savings Over The amount of gas and power used in a plasma
Wet Chemistries. process is very low. Wet chemicals are expensive.
Typical plasma treatment is 10c of gas, 1c of
electricity, 6 mins of hands on processing time

No Residues, Wet treatments require the extra steps of washing
Product Swelling and drying. Drying residues are problematic. PEEK
or Distortion (Poly Ether Ether-Ketone) is a orthopaedic
implantable plastic. In wet treatments it can swell,
distort and subsequently leach.

 MULTIPLE MASS FLOW Process Flexibility Most plasma tools can be used for multiple uses and
CONTROLLERS CAN HANDLE Means a Cost applications, (i.e. etching, cleaning, activating,
VARIOUS GAS MIXTURES. Effective Equipment copolymerizing, polymer coating) on a wide range of
PC CONTROL GIVES UP TO Purchase materials (i.e. plastic, metal, glass, rubber, composites,
bio tissues).

 FULLY AUTOMATED Precise Process Fully automated plasma processes reduces human
PARAMETER CONTROL BY Control Leads to variability and adds consistency, reproducibility and
PC (TIME, POWER, Excellent QC parameter recording.
PRESSURE, GAS VOLUME
STEPS)

Manual Wire and Die Bonders — Operator directs targeting with manual controls
Semi-Automatic Wire Bonders — Operator targets initial bond, machine makes connection
Automatic Wire Bonders — All targets are defined in software, machine bonds automatically
Pull Testers — Wires are stressed to limit or to destruction

Product machines are listed by their Model Numbers within these function groups; however, within the groups, models are further separated by appended Series Letters, generated historically, to distinguish similar mechanism designs and principles of operation. These letters and their meanings are:

“A” — X-Y-Z Single Lever Micromanipulator, original design, three-point follower. Tool Assemblies use mechanical cams.
“B” — X-Y-Z Single Lever Micromanipulator, increased throat depth, follower on balls. Tool Assemblies on four-bar linkage with sliding wire clamps.
“C” — X-Y-Z Single Lever Micromanipulator, constrained axes, pneumatic axis locks. “A” Series Tool Assemblies retained.
“D” — X-Y-Z Micromanipulator of C Series, updated with E Series self-contained wire clamps.
“E” — X-Y-Z Single Lever Micromanipulator, orthogonal straight-line axes, pneumatic axis locks. Tool Assemblies on four-bar linkage with forward pivot. Overhead, gantry construction. Also Moving Head Automatics with orthogonal axes and gantry construction.

Some machines in each Series are “convertible” in that they can be configured by exchange of attached sub-assemblies to perform bonding by different bond methods. They can be identified by repeated method numbers in their Model Number sequence. These numbers are included in the Model Number list of links to aid in finding their defining Specification, even though that Specification is for that model family.

Contact Kevin on 01323 645300 for further information

ADHESION PROMOTION

Plasma activation of electronic connectors and sensors prior to potting and encapsulation ensures an excellent hermetic seal, reduces current leakage and provides stronger physical bonding to the device. Plasma activation raises surface energies and ensures good wettability, and more complete flow of resins onto almost all low energy polymer materials, including PTFE, silicone rubber and Kapton. Polymer surfaces are made bondable by the reactive chemistry present in the plasma. New chemical functional groups are formed with strong chemical bonds to the bulk of the plastic allowing both aqueous based solutions and adhesives to wet into every crevice of the material. This allows a tremendous improvement in bonding, sometimes up to 50 times the strength of the traditional bond.

CRITICAL CLEANING

Residual cleaning of organics at the molecular level on materials such as glass, metals, plastics, polymers or composites prior to bonding, potting, printing, marking, painting or labeling. Plasma de-smear and etch-back of PCB’s allows for the smear left on via walls after drilling to be removed before metallization can occur. In the optical disc mastering industry plasma cleans optical disc stampers, improves replicate release properties, and is used to eliminate certain types of defects on the disk masters.