NPL Introduces Instrument to Measure Performance of Ultrasonic Cleaning Systems

Using aluminium foil to measure the efficacy of ultrasonic cleaning systems seems, well, kind of primitive. According to the UK National Physical Laboratory (NPL), it doesn’t work all that well, either. Yet, that is the recommended means of measurement from the UK National Health Service. The NPL has developed an alternative technology that, it believes, will set a new quality assurance benchmark.

Ultrasonic systems clean devices by passing a high frequency sound wave through a liquid detergent. This creates thousands of small bubbles that implode with such force that the impact removes contaminant particles from submerged materials. To measure system performance, the UK National Health Service recommends the use of aluminium foil, which is eroded and punctured by the imploding bubbles. This method is unreliable and can lead to contamination of the cleaning fluid, according to the NPL, which developed the CaviMeter to counter these concerns.

The CaviMeter consists of a shielded sensor connected by a thin flexible cable to a portable monitor and display unit. By monitoring the acoustic signals generated when the clouds of bubbles implode, the instrument quantifies the cavitation that is taking place at a given location, allowing equipment to be fine-tuned to produce the ideal quantity and distribution of cleaning action. This approach helps ensure that only the required energy is used, reducing cost and environmental impact, says the NPL.

“The Cavimeter is the first device to acoustically map cavitation produced by ultrasonic cleaning systems used in healthcare,” says Mark Hodnett, NPL Senior Research Scientist. The organisation has teamed up with the National Measurement System to conduct further research into ultrasound systems. Next up: using the microbubbles themselves as sensors.

Tags: cavimeter, NPL, ultrasonic cleaning