Ceramic plate speeds blood cleaning

A new ultrasound device for use in open-heart surgery could help patients recover quicker.

The equipment uses a ceramic plate to create ultrasound waves that help clean the blood of micro-emboli – small clots that can block blood vessels.

The firm behind the device, Morgan Technical Ceramics, says it is more flexible and convenient than the filtration and centrifugation systems currently used. It can also be used continuously, is quieter than other devices and doesn’t experience fouling.

Blood is pumped from the patient to the ultrasound unit, which is about 20cm by 15cm in size, where ultrasound is used to remove the micro-emboli while recovering the red blood cells.

‘The speed at which the blood is cleaned is critical,’ Jon Mould, Morgan’s actuator business manager told The Engineer. ‘The quicker you can get the blood clean, the quicker the patient’s recovery.’

The ceramic plate generates ultrasound by employing reverse piezoelectricity, where an electric current causes the plate to expand and contract, creating the ultrasound waves. This technology is more typically used for industrial applications such as ultrasonic cleaning.

‘Our biggest challenge was creating the electrode layer, made from a nickel coating, on the ceramic,’ said Andrew Cooper, Morgan’s actuator engineering manager.

To do this, the firm attached a mask to the plate and then used vacuum deposition to apply the nickel electrode coating in the correct pattern.

Cutting the plate to the correct thickness of 1.4mm also proved difficult. ‘Because of the nickel, the plate needed a superb finish,’ said Cooper. ‘We are used to slicing ceramics but this material is quite hard so it needed a lot of development.’

Morgan developed the device in partnership with ErySave, a firm that specialises in particle separation by ultrasound (PARSUS). ErySave has obtained permission for a doctor working with the firm to trial the device, and large-scale production is expected to start in 2011.