A multidisciplinary research team at Harvard’s Wyss Institute for Biologically Inspired Engineering have fashioned a novel 3D-printed, biocompatible graft that could be used to repair a damaged eardrum. The Phonograft device, as it is called, is also intended to mitigate the pain, drainage, and hearing loss associated with a damaged eardrum.

The eardrum – or tympanic membrane – is a thin but intricate membrane that conducts sound in the ear. The eardrum is however easily perforated by blasts, traumatic injuries, and chronic ear infections, that require reconstructive surgical interventions; surgical failures are common with this type of delicate surgery, making revision surgeries necessary.

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Additionally, patient-derived tissue grafts used as repair very often have imperfect sound-conducting abilities because their structure does not match that of the native eardrum.

After extensive research, the PhonoGraft device was made to mimic the domed shape of the natural eardrum, replete with patterned “wheels and spokes” like a bike wheel. This pattern enables it to vibrate in response to auditory stimulation, and to transmit the sound for further processing by the brain. The Phonograft is composed of a specially developed synthetic polymer-based ink, for 3D printing.

Not only does the implant itself work to restore hearing, but it provides a scaffold for the recipient’s own cells to regenerate. Tests in chinchillas, which have similar ear anatomy and hearing ranges to humans, proved promising.

The researchers believe the novel technology used in the Phonograft could eventually enable permanent repair by first mimicking and then restoring the eardrum’s sound-conducting mechanical properties and barrier functions.

As a bonus, the PhonoGraft can be inserted through the ear canal, thus doing away with invasive surgical repair.

“Three months after implanting our optimised graft into the chinchilla’s ear, we had a genuine eureka moment,” said Dr. Aaron Remenschneider, from the Massachusetts Eye and Ear teaching hospital. “The hearing tests indicated full restoration of sound conduction, which has been a big hurdle. Then we took our first peek down the ear canal with the endoscope. What we were seeing was merely the ghost of our graft that was being replaced with new tissue – a beautifully reconstructed eardrum with its radial-circular pattern.”

According to the researchers, the technology is now entering commercial development as part of high-priority institute project.

A new, wearable ultrasound patch that essentially tracks the rate at which blood flows through a patient’s body can help warn of impending cardiovascular problems such as blockages and blood clot. Engineers at the University of California-San Diego (UCSD), US, developed the patch to continuously monitor blood flow and pressure, and heart function in real time in a non-invasive manner.

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UCSD professor of nanoengineering Sheng Xu, whose team led the device’s development, said it ensures, “a comprehensive, more accurate picture of what’s going on deep in tissues and critical organs like the heart and brains, all from the surface of the skin.”

A single patch – made up of a thin sheet of soft, stretchable polymer – can accurately sense and measure cardiovascular signals as deep as 14 cm (5.5 in) beneath the skin, thanks to a 12 by 12 grid array of millimeter-sized ultrasound transducers known as an ultrasound phased array. The transducers emit ultrasound waves that can penetrate through a major blood vessel and encounter movement from red blood cells; movement changes or shifts in the reflected ultrasound waves will be picked up and analysed accordingly by the patch.

The phased array has two operational modes: all the transducers can either be synchronised to transmit ultrasound waves together to produce a centralised, high-intensity ultrasound beam; or, be programmed to transmit out of sync to produce a wider-reaching ultrasound beam.

“With the phased array technology, we can manipulate the ultrasound beam in the way we want,” explained UCSD postgraduate student Muyang Lin. “This gives our device multiple capabilities: monitoring central organs as well as blood flow, with high resolution. This would not be possible with [just] one transducer.”

Professor Xu highlighted that the ultrasound beam produced can also be tilted to probe different areas in the body – another innovation in the field of wearable technology (existing wearable sensors typically only monitor areas directly underneath it).

In tests, the patch performed as well as a commercial ultrasound probe used in the clinic and accurately recorded blood flow in major blood vessels. The patch is still hard-wired to a computer and power source, but plans call for it to ultimately be self-contained and wireless to better enable “point of care or continuous at-home monitoring.”