Using Plasma Measurement to Improve Medical Device Organisations

Plasma processing is extensively utilized in medical device manufacturing. Applications include the modification of surfaces (to decrease friction or enhance adhesion), sterilization and biocompatible coatings for implants.

Impedans has helped several multinational medical device manufacturers to implement plasma measurement solutions to decrease product scrap and optimize process performance.

They have developed many applications to identify RF-related issues such as arcing and equipment malfunction, which result in reduction in product yield and poor tool performance.

The main applications can be summarized in the following way:

  • RF matching unit tracking at millisecond report rates for sub-second RF sterilization processes
  • Direction current measurement to identify plasma ignition failure at intervals through a 50 Hz power cycle, in processes used for catheter treatment
  • RF impedance monitoring and arc detection for process monitoring of plasma chambers employed for treating several in-vitro medical devices
  • Direct ion energy measurements on multiple shelves (at the same time) in stent and catheter plasma processing chambers

The Process

Firstly Impedans’ development team works with the customer to find the best plasma sensing solution for their application. Next, a custom sensing solution is developed and, lastly, the sensor is made and installed.

If necessary, the software team works together with the company’s IT team to find the best solution for data management. Data is gathered for a wide scope of experimental conditions. Their plasma team collaborates with Impedans experts to analyze the data and find any faulty signatures.

Together with Impedans experts, corrective action procedures are developed. Impedans Protect support packages are available to uphold the accuracy of the custom sensing platform.

The Solution

For a 50 Hz ignition failure application, a custom Langmuir probe design and algorithm was created. In place of the catheter, the Langmuir probe was installed and the measurements demonstrated times when the plasma did not strike, resulting in regions of the catheter that were unprocessed.

These measurements permitted the customer to solve the issue by fine-tuning the equipment. The Octiv RF sensing platform was perfect for millisecond tracking of the matching network in the RF sterilization process. For process monitoring, the customer also utilized the industrial EtherNet/IP protocol.

A custom Semion (retarding field energy analyzer) was developed to be used in a multi-shelf plasma processing chamber application. This system showed that plasma was not igniting between some shelves, leading to stent/catheter scrap. This data was utilized by the customer to track the source of the problem and optimize tool performance.

The Alfven event detector platform and Octiv RF platform were employed to observe plasma impedance and RF arcs in a process utilized for in-vitro medical device processing. This gave the customer invaluable data for their control applications and process monitoring.


The huge pool of plasma and RF expertise built up by Impedans over several years is used by medical device customers to combat their plasma processing issues. Data management and sensing systems are adapted to meet the requirements of the medical device customer.

The return on investment far exceeds the cost of implementation in all instances. As production volumes are ramped up and medical device processing becomes more complicated, smart sensing and data management capabilities become vital requirements.

Using Plasma Measurement to Improve Medical Device Organisations

Image Credit: Impedans

This information has been sourced, reviewed and adapted from materials provided by Impedans Ltd.

For more information on this source, please visit Impedans Ltd.


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