Ultrasonic sensors provide key safety feature

Edited by the Engineeringtalk editorial team Aug 1, 2006

Morgan Electro Ceramics provides materials expertise and piezoceramic components for Debiotech's latest infusion pump, IV Expres

Swiss-based Debiotech specialises in the research and development of innovative therapeutic and diagnostic medical devices.

It works with industrial and manufacturing partners, education institutions and suppliers to develop products based on breakthrough technology.

One such partnership is with Morgan Electro Ceramics who has been providing materials expertise and piezoceramic components for Debiotech's latest infusion pump, IV Expres.

IV Expres is a miniature lightweight infusion pump that accurately dispenses medication and fluids, such as morphine and nutrition, into a patient's circulatory system.

Measuring just 14.0 x 4.3 x 5.8 cm and weighing only 380 grams, it can be used at home, for example clipped to a wheelchair, or in a hospital or alternative care facility.

A key safety feature of the pump is an 'air-in-line' detection system, which monitors for the presence of air bubbles in the fluid.

"Accurate detection of air bubbles is vital in maintaining the health and recovery of patients," says Ary Saaman, QA Director, Debiotech.

"Air embolisms can lead to serious complications in blood flow and the heart's operation".

There are other technologies that are used to detect air bubbles such as infrared.

However, research undertaken by Debiotech showed that for small compact devices, such as the IV Expres, ultrasonic technology provides the most accurate and reliable detection.

Morgan Electro Ceramics was chosen to work with Debiotech because of its materials expertise of piezoceramic sensors for the medical sector.

The sensors use Morgan Electro Ceramics' PZT 5A piezoceramic, a material which is known for its mechanical and electrical properties.

"The sensor works on the principle of a switch," explains Tony Beswick, General Manager, Morgan Electro Ceramic.

He continues; "Two pieces of PZT, tuned to a frequency, are carefully aligned opposite each other, each side of the infusion line".

"An electric current is passed to one piece - the transmitter".

"This sends a signal through the infusion line and fluid to the other PZT - the receiver".

"If there is fluid in the infusion line between the sensors then a signal is received, but when air passes through a reduced signal is received".

"This change in signal generates an alarm, alerting the user that an air gap is present, and the pump automatically stops infusion".

Morgan Electro Ceramics was also chosen for its customised manufacturing capability of complete sensors and the company now produces more than 4000 of the fully assembled IV Expres sensors every year.

Parts are shipped to Delphi Medical Systems who are the license holders of the IV Expres and have rights to manufacture and market the product.

"We needed a partner that could provide both initial technical expertise and a value added manufacturing capability," says Saaman.

"The assembly of the IV Expres sensor is an intricate process".

"Each sensor is potted in a special housing to protect it from any potential external electrical signals and interference".

"Morgan Electro Ceramics was able to deliver on both counts and we were extremely impressed at how quickly everything was in place".

Resistance to wear and its inherent stability make ceramic an ideal material for a wide range of medial applications from implants to surgical tools.

Morgan Electro Ceramics works with many leading medical device manufacturers, providing them with technical expertise and ceramic components for applications including ultrasonic imaging, surgical cutting and bone growth simulation.

The company is already working on more projects with Debiotech such as its micropumps.