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Commercial development of the cochlear implant
Nucleus Ltd
Cochlear division of Nucleus Ltd
Refining the mechanics of the implant
Clinical trials overseas
Cochlear Ltd today
Engineering considerations
Manufacture of the implant

Cochlear - MAIN

To allow the implant to be improved and made accessible to more people it was necessary for it to become a commercial enterprise. Commercialisation of the cochlear implant was essential if it was to be an economically viable project. However the Australian market was too small.

Nucleus Ltd
Nucleus Ltd, a group of companies that manufactured highly developed medical equipment, won a tender to "carry out a market survey and cost development plan for the cochlear implant". (Epstein, 1989: 51)

The four member team responsible for the plan worked on two tasks:

  • research overseas to study market potential
  • a review of the cochlear implant system design — resulting in a simplified version featuring a single integrated circuit.

In 1981, with the University of Melbourne and the Australian government, Nucleus set out to develop a commercially viable cochlear implant and to carry out a worldwide clinical trial.

Reports were written for both tasks and presented to the Australian government. Nucleus Ltd was awarded the contract to develop the cochlear implant.

Cochlear division of Nucleus
Paul Trainor, Chief Executive Officer, Nucleus Ltd, formed the Cochlear Division of Nucleus he then selected a three member Tiger Team.

A Tiger Team, according to Trainor's philosophy, was a small single-minded group moving forward very quickly on a specific project and as far as possible not distracted by the usual day-to-day commitments of a job. They were relieved of much of the bureaucracy and administration so that they could concentrate on the main task, and they were given fully equal or rotating responsibility for accelerating the work. Naturally, as the project matured so did the necessity for red tape and administrative practice, but at the beginning freedom for the job itself was all important. So the small team began and at first constructed the device by hand, acting as designers and manufacturers and checking each other's work for quality control. (Epstein, 1989: 53)

The team increased in size and each member was responsible for a component. The implant was broken down into:

  • implant system design
  • integrated circuit design
  • promontory simulator: a test which demonstrated whether the nerves of the inner ear were working properly.
  • speech processor: received, processed and stored information in a way appropriate to each individual implantee.
  • external electric components
  • automatic gain control device: necessary to expand or compress incoming sounds to an acceptable level.
  • electrode array
  • implantable stimulator. (adapted from Epstein, 1989: 53)

Refining the mechanics of the implant
A newly emigrated Polish mechanical engineer, Janusz Kuzma, was responsible for the mechanical aspects of the implant. He

…had to devise a way of sealing (the implant) hermetically with biocompatible material as well as incorporating a mini antenna coil to pick up the signals. He solved the latter problem by looping the coil outside the small round device and enclosing the whole in soft silastic. A new electrode system with 22 electrodes had to be accommodated, and he was also responsible for the design of the external headset. He knew the electronic parts would not function correctly unless the mechanical parts were perfect. He knew the team was dependent on and accountable to public funds. He knew there was a time limit and time was running out. He had many sleepless nights. … (Epstein, 1989: 54)

Building on the University of Melbourne research, Cochlear developed the more advanced 22 channel implant and the wearable speech processor (WSP). The design philosophy was to make a flexible cochlear implant with sophisticated sound processing in the externally worn speech processor. This allowed the recipient to take advantage of improvements in technology without surgically replacing their implanted device.

Twelve months after the team began it had managed to completely redesign the whole cochlear implant system and develop an implantable device. The system was ready for clinical trials.

Clinical trials overseas
Clinical trials of the Australian cochlear implant were set up in Australia and overseas. Competition in electronic engineering and microchip technology in medical devices was world wide and the Australian government wanted to capture some of the overseas market.

For the Cochlear implant to be available to the American market, and indeed world wide the US Food and Drug Administration had to give its official approval. This was achieved in 1985.

Cochlear Ltd today
Since 1988, Nucleus, including Cochlear, had been a wholly owned subsidiary of Pacific Dunlop. In 1995, Cochlear was sold by Pacific Dunlop and floated on the Australian Stock Exchange, as a publicly listed company.

The Nucleus® 24 Contour implant won the Australian Design Award™ of the Year in March 2000. It has some important features:

  • an electrode that is curved before insertion into the cochlea
  • it places the electrodes closer to the important parts of the cochlea
  • does not exert any force on the bone or tissue after it is inserted.

Engineering considerations
Some significant engineering considerations were addressed in the development of the Nucleus® 24:


Easy insertion
Ability to insert a pre-curved electrode array that is designed to fit inside the inner wall of the human cochlea and has a coating which is moulded from silicone into the correct shape. To insert the electrode into the cochlea it is temporarily held straight using a fine wire stylet. Once inserted, the stylet is removed. The electrode must be flexible enough to move around the cochlea without causing trauma and have sufficient memory to return to its original curved shape. The stylet also must be easily removable and all components must be easily manufactured.

Simulation of contour insertion
Simulation of contour insertion (New York University)
Simulation of contour insertion


The implant is made from titanium, silicone rubber and platinum. The sophisticated electronic sub-assembly is encapsulated by the titanium shell. The electronic package is connected to the electrodes by insulated platinum wires about 25 microns in diameter. The electronic package is implanted into the mastoid bone in the skull. The titanium shell must prevent bodily fluids from entering the package, but also have a connection to the 22 electrode array and the radio frequency antenna outside the package. The device also needs to be strong enough to withstand surgery and implantation and subsequent flexing for its design life of 70 years.

3. Long term reliability
The implant is guaranteed for ten years but designed for a life of 70 years.
4. Safety during insertion and after receiving the implant
After implantation the processor and system must be customised for each individual. During programming of the device it is important that the recipient is not exposed to excessive stimulation which could be painful.
5. Ease of manufacture
The implant is handmade under a microscope.

Manufacture of the cochlear implant

Production of the speech processor
The behind-the-ear (BTE) speech processor differs from a conventional body-worn speech processor, as it contains a directional microphone, contained within the same case as the speech processor unit. The production processes for each processor are very similar.

assembly of the cochlear
Precision assembly of the cochlear implant (Cochlear Pty Ltd)

1. The ten-layer, double-sided circuit board, which is the heart of the body-worn processor, is mounted with six integrated circuit components as well as capacitors, transformers, resistors and other components.
2. A pick and place machine is employed to automatically place and solder components to the gold pads on the board, according to a program that is loaded for each different circuit board configuration. The push button switches, which are eventually operated by the external buttons, are manually soldered to the board, as are connectors (which are used to connect cables to the test system during testing), a lithium battery and a power transformer.
3. The circuit board, which is made up of flexible and rigid parts, is tested and then fixed to the plastic casing.
4. The control panel, with buttons and LCD window is assembled onto the moulded plastic case.
5. The closed processor is tested to ensure that the circuit is functioning correctly, before it is baked overnight, and then re-tested.
6. The small double-sided circuit board of the BTE processor contains a custom integrated circuit, which is protected by a blob of semiconductor coating, and other components. The microphone, potentiometer (an adjustable resistor which is seen as the dial from the outside), and switch, are soldered to the populated board and everything is placed into the case.
7. The RF socket and the battery terminals are connected to the circuit, before the board is coated.
8. The closed processor is tested, before the cover and the ear hook are attached.

Production of the cochlear implant
The Cochlear implant itself is made up of three main functional components:
1. the stimulator
2. the antenna coil and
3. the electrode unit.

The heart of the stimulator is the Cochlear implant chip, an integrated circuit. The stimulator also contains a ceramic disk, or feedthrough, with twenty-four platinum pins to which each of the twenty-two electrode wires, and two coil wires, are attached in the final assembly. The stimulator is responsible for picking up the signals from the antenna, and sending out the appropriate electrical energy to the electrodes. The stimulator is encased in titanium shells, which are laser welded together.

The antenna coil, which forms the loop of the implant, is welded to the stimulator, to form a functional antenna. It is then wound into the shape that you see in the final implant. An extracochlear electrode is assembled, using fine platinum wire, and is also attached to the stimulator. Stimulator components are prepared and cleaned prior to entering the clean room. All antenna coil assembly is conducted in the cleanroom.

assembly of the cochlear
Most of the assembly operations for the behind-the-ear speech processor and the stimulator assembly are done under a microscope. In the stimulator production and external production areas, controls are in place to protect the statically sensitive devices being handled, therefore operators wear special lab coats, wrist and heel straps for grounding, and gloves.
(Cochlear Pty Ltd)

The cleanroom is a totally controlled environment with set temperature and humidity levels, where electrode assembly and final implant assembly takes place. Strict controls are required during the final assembly of implants to ensure that the final product is clean, and after sterilisation, ready for implantation. Full body garments are worn in the cleanroom, from boots, overalls, hood, mask and gloves.

The electrode unit can either be made up of a straight electrode array or a contoured array.

1. Each platinum electrode wire is welded to a platinum ring. The wires are fed through the rings, and one at a time, each wire is attached to one ring. A lead wire is attached and the whole thing is encased in silicone.
2. This electrode unit is attached to the stimulator, and the individual wires are attached to the corresponding pins on the stimulator.
3. The assembly is electrically tested and then silicone is injected to insulate the stimulator.
4. The outside titanium shell is laser welded to the stimulator, and the unit is tested again.
5. The implant assembly is baked overnight in a vacuum oven, and then undergoes final hermetisation, which means that the small hole in the stimulator shell is fused resulting in a gas-tight seal around the stimulator.
6. A small magnet is then inserted in the outer moulding and the entire implant assembly is placed in a moulding die into which silicone is injected, to completely encase the implant.
7. The implant is bent so that the coil is at an angle to the stimulator and the magnet is removed.
8. The implant is washed, the magnet reinserted, and the assembly is electrically tested.
9. Finally the product is packed in a sterile pouch, this complete assembly is sterilised, and the implant is packed.

This is a basic overview of the manufacturing processes involved in producing the components necessary for a functional Cochlear implant system, which transmits signals from outside the body, to the electrode inside the cochlea, allowing the recipient of the implant to hear. Text provided by Cochlear Pty Ltd.

Design process
The following two diagrams illustrate the design process flow. They incorporate the philosophy of plan, do, check, act used by Cochlear Pty Ltd.

Process flow

Process flow (Cochlear Pty Ltd)

Click to view larger image
Design process flowchart indicating the stages involved in developing a product. Note the tollgates or check points throughout the process. (Cochlear Pty Ltd) Click image to view enlarged version.

At significant points in the design process Cochlear has set up tollgates or check points where approval from a management team is required before the process can continue. Refer to the design process flowchart when considering the information in the table.

When it occurs
Approval to proceed to:
1 Project start System development
1A Completion of system design Design
2 Completion of detailed design Process development
3 Completion of implementation Pilot production
4 Completion of pilot production, Clinical trials Production
5 Completion of market stability assessment Sustaining engineering

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