Contactless ultrasonic sensors facilitate hygiene and help prevent contamination. The clamp-on sensors have many advantages, especially in single-use systems, such as those being used increasingly in pharmaceutical production.
Process chains consisting of many sterile single-use systems are preferred especially in the production of highly active, small to medium-volume biopharmaceuticals such as vaccinations. There are several reasons for this: the investment costs for such systems are low. These systems can be set up and put into operation quickly, lower the risks of contamination, speed up processing times, and reduce the amount of cleaning required. Furthermore, they protect the user in situations when cytotoxic substances and highly active biological materials are used. Still employees have to wear personal protective equipment to ensure that they do not come into contact with the reagents. Since wearing protective gloves can make working with small switches, hoses, and other devices difficult, all single-use technology components have to be as easy to use as possible.
Based in Halle, Germany, Sonotec Ultraschallsensorik Halle GmbH designed a single-use version of its clamp-on sensor Sonoflow CO.55 for these types of applications. This contactless ultrasonic sensor reads the dosage and flow rate at any point where liquids are automatically being added to a batch in the production of pharmaceuticals. The sensor can take measurements in PVC and flexible tubing and can even be retrofitted into various devices. A special holder is not needed as the sensor attaches to the tubing directly.
The developers modified the sensor’s material and design for the single-use model: the new stainless steel version CO.55 is also approved for use for cleanrooms; has its own locking mechanism, making it easier to use with gloves; and is available for various tube diameters.
Contactless clamp-on ultrasonic sensors are also in demand in a new DNA analysis system. Tiny air bubbles can form in the liquid being analyzed during the sequencing process. Bubbles less than the size of 1 µl would be small enough to damage the sample or produce incorrect results. The Sonocheck clamp-on air bubble detectors type ABD06.85 are even able to detect bubbles smaller than 1 µl. These detectors can be used with PEEK and PTFE tubing that have an internal diameter of 0.79 mm (external diameter: 1.59 mm).
The ABD06 sensors belong to a series of clamp-on ultrasonic sensors that detect air bubbles in fluid-filled tubes and measurement chambers, allowing them to monitor fluids and send out wet/dry alarm notifications. They adapt to dynamically changing acoustic conditions, which gives them the ability to reach high measurement stability despite fluctuations in the surrounding environment. The measurement cycle takes 200 µs, and the reaction time is usually 1 ms. A micro-controller with expandable functions, such as fail-safe and serial communication features, can be used to program the ultrasonic sensor for each application.
One version from the ABD06 series is used, for example, to fill biological protein products where even the smallest bubble is not allowed. Sonocheck ABD06 detects air bubbles smaller than 1 µl in PTFE tubing even in this environment. This detector is equipped with software that makes configuration easy and allows sensor output to be monitored. The user can also use the serial communication protocol to estimate bubble size and track the estimated loss of fluid.
The redundant Sonochek ABD08 sensor is another clamp-on ultrasonic sensor for non-invasive air bubble detection. This patent-pending, square device combines two ultrasonic sensors into one casing with sides that are 35 mm long. It complies with the third edition of European Standard EN 60601–1 and meets the FDA requirements in regard to the reliability and accuracy of sensors used in medical devices.
The redundant sensor design prevents air bubbles from getting into the patient’s bloodstream. But the integration of the two sensors in a single casing caused electrical crosstalk to occur in the two ultrasonic channels. Sonotec solved the problem by creating a design that holds not only the electronics, but also the acoustic path.
All of the ultrasonic sensors introduced in this article can be connected to a computer through a serial interface, allowing for easy configuration and display of readings using monitor software. With this feature, the user can test the sensors and adapt them to the present requirements—within predefined limits. Any other application-specific modifications to design, interfaces, and safety routines or power supply will be undertaken by the sensor manufacturer.
Anne-Luise Gellner Sonotec Ultraschallsensorik Halle, Halle, Germany
Additional information Sonotec develops and manufactures customer-specific ultrasonic transducers and sensors, testing equipment, and measurement technology solutions. Its products are used, among others, in the medical technology and chemical-pharmaceutical industry. www.sonotec.eu
Teilen:
