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German Fraunhofer Institute for Photonic Microsystems Develops Ultrasound Transducer to Assist in Medical Diagnosis

October 21, 2019 by Luke James

A brand-new type of ultrasound otoscope has been developed at the Fraunhofer Institute for Photonic Microsystems (IPMS) and is expected to facilitate faster and more reliable diagnoses of middle ear infections.

Fraunhofer's prototype ultrasound transducer should soon be able to deliver fast and reliable middle ear infection diagnoses.

Both the Fraunhofer Institute (IPMS) and OtoNexus, a U.S. company, are collaborating on the development and application of this technology. The transducer is integrated into an otoscope and aids physicians in diagnosing infection and deciding whether antibiotics are necessary. 


Aiding Ear Infection Diagnosis

Otitis Media (OM) is a type of middle ear infection that is the number one reason for antibiotic prescriptions in paediatric medicine and the leading cause for surgery. This is the case globally. Almost every single child on the planet will suffer a middle ear infection that is severe enough to warrant seeing a doctor, and many will suffer repeat occurrences of them during childhood. 


Image courtesy of Fraunhofer IPMS

Image courtesy of Fraunhofer IPMS.


U.S. CDC research and other studies have shown that diagnostic error rates for middle ear infections average around 50 percent, particularly when making the distinction between a viral and bacterial middle ear infection. This means that many viral middle ear infections are wrongfully diagnosed, and antibiotics are inappropriately prescribed to help treat it. This, of course, is not only expensive but does nothing to help quell the problems we are facing re. antibiotic resistance.

Conversely, underdiagnosis of middle ear infection can result in the need for surgical intervention or, in more extreme cases, hearing loss.


The Ultrasound Otoscope

The current otoscope design has been used to diagnose ear-related ailments for decades and has been virtually unchanged since its inception. It consists of a magnifying lens, battery, and light source. This provides only a limited view of the eardrum, however, being able to accurately know of the contents of the middle ear on the other side of the eardrum is key to accurate diagnosis. 

So, the need for a more accurate way of diagnosing middle ear infections is apparent—that's exactly what Fraunhofer IMPS' transducer-powered otoscope does. 

The transducer emits ultrasonic pulses and captures the echo reflected by the eardrum. Using this data alone, the device can generate a reading that tells the doctor or another medical professional about the degree of infection.

Dr. Sandro Koch, a physicist at Fraunhofer IMPS, said, “The classic otoscope is an optical system and hasn’t changed in decades…. But when fitted with our ultrasound transducer, which is both a transmitter and receiver, it develops new functions.”

This is done using air coupled with ultrasound to facilitate the precise diagnosis of middle ear infections. A capacitator formed by two electrodes is separated by a small air-filled gap. One of the two electrodes is flexible, and the device uses vibrations of this electrode to transmit ultrasonic pulses. When the echo from this signal hits a membrane, the vibration is converted into an electrical signal that can be detected and used for data analysis. 


Suitable for Mass Production

The ultrasound transducer is a capacitive micromachined ultrasonic transducer, or CMUT. It is produced on a silicon wafer using proprietary MEMS technology developed at Fraunhofer. It has low power consumption and can easily and cheaply be produced en masse. And, unlike other CMUTs, this one can be miniaturized for easy deployment into an otoscope.

Other potential applications for the MEMS CMUT include distance measurement in robotics, smartphones and tablets for gesture control, and onboard vehicles for infotainment system control. 

The new otoscope featuring a Fraunhofer CMUT is currently at the prototype stage with market launch anticipated within a few years. The device is being manufactured by OtoNexus Medical Technologies using Fraunhofer sensor technology. 

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