Module stacking enables sensation-free compact hearing aid

Fraunhofer researchers are developing a new microsystem designed to make hearing aids small enough to be concealed out of sight within the ear. 

Part of the EU WiserBAN project, the research is expected to lead to hearing aids that are more comfortable and efficient.

‘Ideally, patients should not even be feeling of wearing the hearing aid over long periods of time,’ said Dr. Dionysios Manessis from Fraunhofer Institute of Reliability and Microintegration IZM in Berlin.

With dimensions of 4mmx4mmx1mm, the new microsystem is fifty times smaller than the current models for body area network (BAN) applications. To achieve this, the project partners first developed miniature antennas, system-on-chip integrated circuitry and high frequency filters.

The Fraunhofer researchers then integrated a total of 19 components into a single module.

‘This is a real challenge as all the components are of varying sizes and thicknesses. But having exploited various embedding technologies, which lead to advanced system-in-package (SiP) miniaturisation, we have managed to arrange all the components in the smallest possible space – just as in a package,’ Manessis said in a statement.

The Fraunhofer team saved extra space by building the components into several smaller modules and then stacking these on top of each other.

Project partners are also looking to optimise energy management. Hearing aids worn behind the ear are powered by a 180mAh battery, which must be either replaced or recharged approximately every two weeks.

The next step is to minimise the system’s energy consumption to around 1mW and extend battery life to up to 20 weeks.

The overall aim of WiserBAN is to develop wireless body area networks (WBAN) that can improve personal sensing capabilities by using miniature, unobtrusive, long-life sensor nodes.

The FP7 project is expected to deliver wearable and implantable radio microsystems for healthcare applications and systems are envisioned for cardiac implants, insulin pumps, and cochlear implants.

To this end, the project partners are developing antenna and wireless protocols that serve to communicate information such as pulse, blood pressure or glucose levels straight to a doctor’s tablet or smartphone.

The resulting WiserBAN wireless system negates the need for a relay station, an extra device that patients have previously been obliged to wear to extend the communication range.

According to Fraunhofer, another advantage is that the wireless protocols developed within the project are based on IEEE 802.15.4 and 802.15.6 standards. Conventional devices have ordinarily relied on Bluetooth, where there are often issues with interference with other devices.