Health Sciences · Hospital for Sick Children
A cochlear implant covered in a soft casing made of transparent silicone. The main body of the unit consists of a circular element, the receiving coil with a magnet at its centre. The magnet is used to attach an external component, the external RF coil, to the skin opposite the implanted element. A flexible opening in the silicone cover allows for it to be removed if the patient requires an MRI.
Adjacent to the receiving coil on the implanted element is an internal stimulator, housed in a titanium case. This performs signal processing and transmits electrical pulses to the electrode array.
Two long, thin silicone-covered electrical elements emerge from the internal stimulator. One terminates in an electrode array that is implanted within the cochlea. The other is an extracochlear reference electrode that serves as a return electrode.
The silicone skin on this implant has been damaged with handling and has been repaired with a piece of adhesive tape.
Accession Number: 2025.sk.57
Alternative Name:
Primary Materials: Silicone, Titanium.
The word “DEMO” is moulded into the silicone case on the bottom surface of the receiving coil.
Dimensions (cm): Height = 15, Width = .4, Length = 3.4
Cochlear implants are used for severely to profoundly deaf patients for whom acoustic amplification offers no benefit. A cochlear implant stimulates the auditory nerve tissue directly using electrical signals in order to create a sensation of hearing.
A cochlear implant consists of two separate components, an internal element with an electrode array implanted within the cochlea, and an externally worn component. The external element contains such things as a microphone, a battery, a sound processing system, and a transmitter that sends the sound signal and power to the implant.
This is a demonstration unit representing a Nucleus 24 cochlear implant, which was commercialized in the late 1990s. The implant’s main casing is meant to be surgically inserted beneath the skin behind the ear, with its electrode array implanted into the cochlea.
The artifact appears intact. The silicone skin is torn in two places: on the perimeter of the magnet hole and along the edge near to where the electrodes attach to the main unit.
Associated Instruments:
Manufacturer: Cochlear Pty, ltd., Sydney, Australia
Date of Manufacture: Late 1990s
This is part of a small collection of artifacts, gathered by Archie’s Cochlear Implant Lab at The Hospital for Sick Children (SickKids), that was photographed on 8 October 2025. The items represent various stages of the technology used since the lab’s founding in 1998.
These items remain on site and in possession of the Lab. They are used for teaching and demonstration purposes.
James F. Patrick, Peter A Busby, and Peter J Gibson (2006). “The Development of the Nucleus® FreedomTM Cochlear Implant System.” Trends in Amplification 10, no. 4: 175–200.
Karen A. Gordon and Blake C Papsin (2013). “From Nucleus 24 to 513: Changing Cochlear Implant Design Affects Auditory Response Thresholds.” Otology & Neurotology 34, no. 3: 436–42.
Cochlear, ltd. was founded in 1981 based on developmental research into cochlear implants by a group led by Dr. Graeme Clark at the University of Melbourne, Australia. This followed a decade of research in areas such as biocompatible materials and safe thresholds of electrical stimulation with the cochlea. The company’s first-generation cochlear implant system, based on the Cl22 implant, was commercially released for adults in 1985. (See Patrick, Busby, and Gibson 2006, 177.)
This is the initial (CI24M) version of the Nucleus 24 cochlear implant was released in 1997. The Nucleus 24 was approved by the FDA in 1998, supplanting the earlier Nusleus 22 implant, though the company continued to support the earlier implant in its ongoing product development.
The Nucleus 24 features a 16.4 mm array of 22 electrodes spaced evenly at 0.45 mm. The device was subsequently modified over several generations.