Learn how developing standards-approved cleaning procedures for precision medical and surgical components such as titanium implants and endoscopic devices are facilitated with benchtop ultrasonic cleaners. Here are guidelines on selecting your ultrasonic cleaner, accessories and cleaning chemistries.
Benchtop Ultrasonic Cleaners Facilitate Cleaning Process Development for Medical Devices and Implants
Ultrasonic energy is widely accepted to remove contaminants including free iron, chips, and machining oil residues, and to passivate stainless steel, on products such as endoscopes and surgical implants. Benchtop ultrasonic cleaners help develop standards-compliant procedures for scale-up to production-line cleaning, passivating, rinsing and drying systems.
Why Ultrasonic Energy is Preferred for Cleaning Medical Devices
An ultrasonic cleaner for medical parts uses the scrubbing power of imploding microscopic bubbles to loosen and carry away surface contaminants on instruments immersed in specially formulated cleaning baths or solvents. The process, described as ultrasonic cavitation, is explained in the post How Ultrasonic Cleaners Work.
Ultrasonic medical parts cleaning is favored for:
Speed: Cleaning is faster than mechanical washing.
Thoroughness: Reaches all surfaces immersed in the cleaning bath – surfaces that can be missed by mechanical or manual cleaning.
The following information provides guidelines on
- selecting your pilot-scale ultrasonic medical device cleaner – capacity and features
- ultrasonic cleaning baskets, fixtures and accessories – critical for thorough cleaning
- ultrasonic cleaning chemistries for medical devices, and
- using volatile solvents to clean medical device components
Selecting a Pilot-Scale Medical Device Ultrasonic Cleaner
Ultrasonic cleaners are offered in a variety of sizes, defined as cleaning solution volume and cleaning tank dimensions. An example for pilot-scale research is the 1.5-gallon Elmasonic Select 60 that stores up to 4 frequently used cleaning programs for quick recall.
The Select series is offered in 11 models up to 23.5 gallons in the Select 900 unit.
This series offers a number of performance-enhancing features that may be useful in achieving thorough medical device cleaning. Already mentioned is the ability to store up to four frequently used cleaning procedures. This can save valuable set-up time when evaluating candidate cleaning procedures. Here, in brief, are
Elmasonic Select Series Features and Benefits
| Sweep Mode | Uniformly cleans all surfaces |
|---|---|
| Pulse Mode | Power bursts remove tenacious contaminants |
| Dynamic Mode | Combines Sweep and Pulse |
| Eco Mode | Gentle cleans highly finished surfaces |
| Degas Mode | Speeds prep of fresh cleaning chemistries |
| Heater | For recommended cleaning solution temperature |
| Digital Timer | Set cleaning cycle from 1 minute to 6 hours |
| Drain | Remove spent solutions prior to replacement |
Ultrasonic Cleaner Baskets, Fixtures and Accessories
When selecting an ultrasonic cleaner for medical parts, there are additional points to consider beyond cleaning tank dimensions.
That’s because cleaning is best accomplished in baskets, the dimensions of which are slightly less than tank dimensions.
Baskets are designed to suspend parts at the proper level in the cleaning bath for optimum cleaning action. Another key consideration is parts must be fully immersed, without crowding, in the cleaning solution. A key takeaway here is best results can be achieved by running multiple cleaning cycles rather than trying to save time by cleaning too many parts in a single cycle.
As examples, the Elmasonic Select 60 mentioned above has tank dimensions of 11.8 x 5.9 x 5.9 inches (L x W x H) and recommended basket dimensions of 10 x 4.1 x 3.7 inches.
The Select 900 ultrasonic cleaner has tank dimensions 23.6 x 19.7 x 11.2 inches (L x W x H) and basket dimensions 21.5 x 18.1 x 7.5 inches.
Modular Baskets and Fixtures Boost Cleaning Effectiveness
Medical device components and implants come in a variety of sizes and configurations that can be a challenge to clean. Modular basket systems facilitate parts placement for maximum cleaning efficiency.
The basket systems are designed to accept a broad variety of inserts and fixtures. These allow cleaning process developers to create compartments, levels, and position complex medical parts in ultrasonic baths by using pin sets, comb holders and other components.
Other useful accessories include mute boxes to reduce noise, and drying units to speed cleaning and rinsing solution evaporation.
Additional resources on baskets, fixtures and accessories can be found in the product information catalog and on our accessories web page.
Ultrasonic Cleaning Chemistries for Medical Devices
Contaminants remaining on surfaces of newly manufactured medical devices and implants can include oil films, free iron and other small particles.
Ultrasonic cleaning chemistries, or formulations, are available to help meet these challenges. Here are examples:
Removing oil films and similar contaminants from newly fabricated and machined parts is achieved with biodegradable elma tec clean A4 universal degreaser available in 2.5, 10 and 25-liter containers. This mildly alkaline, demulsifying formulation can be diluted with water to a 1 to 5% solution to remove oil films and residues remaining from fabrication processes or other parts-handling steps.
Cleaning sensitive parts such as medical and laboratory instruments and implants made of aluminum and light metal alloys, glass, ceramic and plastic is accomplished with neutral, foam-inhibited elma lab clean N10 diluted to 2% with tap or Di water.
Passivating stainless steel endoscopy components and implants is achieved with mildly acidic, demulsifying elma tec clean S1 diluted to 10 to 20% with water.
Using Volatile Solvents to Clean Medical Device Components
If low-flash-point volatile solvents such as IPA, acetone and toluene are employed to provide residue-free cleaning, such as required for surgical implants, special equipment and operating procedures are called for.
This is because the use of such solvents creates what is termed a hazardous location. National, local and company regulations* dictate the positioning and operation of equipment used in these applications.
Options for Flammable Solvent Ultrasonic Cleaning
For small parts, consider a flammable solvent ultrasonic beaker kit placed in a well-ventilated area.
Kits contain:
- a benchtop ultrasonic cleaner
- two beakers and caps in either 600 or 1000 ml capacity
- beaker support rings and
- a two-holed lid to support the beakers, at the proper level, in the tank
Optional fine-mesh baskets sized to fit in the beakers can be used to contain very small parts.
In brief: The ultrasonic cleaner tank is filled with water plus a surfactant.
Small medical parts can be placed in the beakers or fine mesh baskets. Solvent is added to cover the parts; beakers are capped and inserted into the two-holed lid. Beaker bottom should be positioned one to two inches above the tank bottom.
When the unit is activated, ultrasonic energy passes through the beaker walls to act on the medical device components.
Equipment options and a full description of the process is covered in How to Use Ultrasonic Cleaner Beaker Kits for Flammable Solvents.
Large-Part Cleaning with Flammable Solvents
For large-scale flammable solvent ultrasonic cleaning, process development labs should use code-approved* explosion-proof ultrasonic cleaners. An example is the SOL XP flammable solvent ultrasonic cleaning system offered in 6 tank capacities from 2 to 33 gallons.
SOL XP systems feature remote electrical panels and generators, intrinsically safe tank circuits, and a nitrogen-purged transducer enclosure – all aimed at isolating potential ignition sources from the solvent. Options include:
- Cooling jackets capture vapor and reduce odor
- Solvent filtration systems prevent contaminant redeposition and extend solvent life
- Mesh baskets position parts at the proper level in the tank to maximize cleaning effectiveness
- Containment pans for spills
More information and other resources on these units are provided on the SOL XP Product Data Sheet. For a general overview on this critical topic, check our post How to Select an Explosion-Proof Ultrasonic Cleaner.
Other Useful Resources on Ultrasonic Cleaning
How to Use an Ultrasonic Cleaner
A Cleaning Solution Selection Guide
*Codes and standards may include the National Electric Code (NEC/NFPA 70), NFPA 496 for purged and pressurized enclosures, UL 698A for industrial control panels for hazardous locations, along with NFPA 91 for exhaust systems, requirements imposed by local authorities having jurisdiction (AHL), and company-specific safety policies.