Magnetic sensor spells relief for acid stomach

Do you sufferer from stress-related gastroesophageal reflux disease? If you do then you will be more than interested in a new wireless, remote query sensor that could help you out.

GERD, or esophagitis, is a common digestive problem. Reflux occurs when gastric acid moves from the stomach up into the esophagus, causing heartburn, chest pain, cough, or asthma, as well as complications which include esophageal cancer.

Conventional diagnosis involves passing a catheter connected to recording electronics through the nose, then down the esophagus, where it is then left in place for 24 hours. The procedure is so unpleasant that about half of patients refuse it.

The new sensor technology, developed at the University of Kentucky in Lexington with support from ENG’s Electrical and Communications Systems Division and the National Institutes of Health, offers a less invasive way to detect gastric reflux.

The sensor allows a wide range of measurements—of temperature, pressure, fluid flow velocity, chemical analyte concentrations or the viscosity of liquids—without need for a physical link between the sensor and the measuring dial.

The sensor is based on a polymer-coated magnetoelastic film that changes shape according to its environment—in the reflux work, according to changing levels of gastric acidity.

Changes in the film’s shape result in changes in its resonance frequency, and these changes are picked up by a receiver coil that is worn by a patient. The sensors require no batteries, as they are powered by the interrogation signal; and the materials cost is only a few pennies.The device itself is suitable for two applications.

‘In the first one, the patient swallows a small piece of polymer-coated film, which goes naturally through the digestive tract, sending out its measurements of pH and pressure along the way,’ Grimes says.

The sensor can also measure acid levels near the stomach opening for a day or two. ‘Instead of going through your nose, [doctors] go down the esophagus with a thin tube, clip the strip-like sensor to the live esophagus tissues just above the stomach opening, and remove the tube,’ says Grimes. ‘The patient should not feel the small piece of film. As tissue cells are continually replaced, the clip floats free within two days, and passes through the digestive tract.’

The Kentucky researchers have filed five patents on the sensor technology.

For more information, contact Craig A. Grimes at: grimes@engr.uky.edu.