Researchers at the Department of Energy's Pacific Northwest National Laboratory developed a patented inspection method that uses sound waves to detect foreign objects in processing streams. Originally developed to look for bone fragments and foreign materials in chicken breasts, the method can also detect cartilage, metal and plastic -- essentially anything that shouldn't be in the product. Battelle, which operates PNNL, funded the research and the method is available for licensing.
A process stream is typically a continuous flow of slurry or liquid that goes through multiple steps on its way to becoming a finished product. During processing, objects can fall into the mixture, bones can be left in meat, or pits and seeds may be left in fruit.
The PNNL-developed method combines both ultrasonic and optical capabilities.
"Our method is the only one we're aware of that uses both acoustics and optics," said Aaron Diaz, PNNL staff scientist. "Because it can be automated, it's inherently safer and more effective than inspecting certain types of process streams manually. And automation eliminates the need for costly and slower inspections using methods such as x-ray, which typically requires added safety precautions and complex operator training."
Acoustics, combined with transmitted light through the product, adds to the data extracted from the stream, making results more accurate. The two methods, however, can be used separately, depending on the properties of the product being inspected.
"Our process involves multiple sensors configured along the process stream," continued Diaz. "We flood the stream with sound pulses of acoustic energy, while at the same time transmitting optical energy. We're looking for reflected echoes that we can correlate with location, such as depth and lateral position, in the stream relative to the product's flow rate. If the received acoustic response is abnormal, it indicates there's something in the stream that shouldn't be there and we know, generally, where the foreign object is."
Unwanted objects can also occur "naturally" in a process stream. In chicken breasts, for example, components of the raw materials may be unintentionally left in the breast during a separation process.
The challenge in using acoustics to examine chicken breasts is the innate presence of air bubbles within the chicken "slurry." These bubbles reflect sound energy. The reflections may be interpreted as bones or other materials, making the PNNL-developed method ill-suited for its original purpose.
Fortunately, these limitations don't prevent it from being useful in other applications.
For example, no one wants foreign objects in baby food. The "first step" baby foods, usually popular pureed fruits and vegetables, could also be examined with this method.
"Although the original application presented some challenges and, ultimately, didn't work out, it's a useful technology that could positively impact manufacturing in many other areas," said Diaz.
For licensing and other business inquiries, contact David Greenslade at 509-375-6555.
PNNL is a DOE Office of Science laboratory that solves complex problems in energy, national security, the environment and life sciences by advancing the understanding of physics, chemistry, biology and computation. PNNL employs 4,200 staff, has an annual budget of more than $725 million, and has been managed by Ohio-based Battelle since the lab's inception in 1965.