Bionics is defined as the union of biology and electronics. Unlike prostheses, the bionic implant actually mimics the original function of the body part, sometimes surpassing the power of the original organ or other part. It enables the replacement or enhancement of organs, processes or appendages with electronic or mechanical components.As with other life saving devices such as drug coated stents and artificial heart assist devices, patients will drive the use of bionics.

The most common and well known of these bionic technologies include cochlear implants and the artificial heart. There are several major target areas for researchers including bionic muscles, brain/electronic interfaces, artificial organs, and retinas.

Artificial Retina
In the U.S. there are two major types of retinal degenerative disease that end in blindness: retinitis pigmentosa (RP) and age-related macular degeneration (AMD). These conditions affect 500,000 (RP) and 12 million (AMD) patients in the U.S. Currently, there is no cure for either of these diseases but their progression can be slowed with surgery and drug therapy.

Until a cure is found or artificial eyes are available, one solution is to replace the patient's eye tissue with an artificial retina. Optobionics' solution is the Artificial Silicon Retina (ASR), a microchip that is designed to stimulate damaged retinal cells, allowing them to send visual signals again to the brain via the optic nerve. The device is based on an extremely small silicon microchip, 2 mm in diameter and 25 microns thick. In the chip there are 5,000 microphotodiodes or microscopic solar cells. These microphotodiodes are designed to convert the light energy from images into electrochemical impulses that stimulate the remaining functional cells of the retina. One advantage of the ASR system is it is powered by light. Thus, it does not require the use of external wires or batteries. The ASR system will require surgery to implant the chip under the retina.

The Second Sight device uses external sensors to acquire light and supply power. It also requires a two-hour surgical procedure to implant an electrode array on the retina. The array is used to electrically stimulate the viable retinal cells. The resolution of the image depends on the number of electrodes used.

Artificial Muscles
Natural muscle has the ability to repair and strengthen itself, contract and expand, generate stresses, transform to fuel in a body's starvation state, and convert energetic fuel to mechanical energy.

There are many potential applications for artificial muscles. Lab tests showed that these devices have a lifting strength more than 100 times that of normal skeletal muscle. This enables the technology to be used to replace appendages or heart muscles, to be used in the urinary sphincter to treat incontinence, and as an artificial diaphragm to help people breathe. It can also be used to provide the scaffolding for healthy tissue growth for transplantation.

Researchers have focused on two forms of bionic muscles. Both of these are based on using a "memory wire" that mimics natural muscle fibers. One design focuses on powering artificial muscles with alcohol and hydrogen. These chemicals act as catalysts that cause the wire to bend and then return to its natural shape.

The other technology first converts chemical energy into electrical energy. The electrical energy causes carbon nanotubes to change shape in response to the electrical current. This technology is referred to as an Electroactive Polymer Artificial Muscle (EPAM). It is a rapidly emerging motion technology that has significant advantages. EPAM technology can produce 20% more energy than motors and has a longer life expectancy. This will allow it mimic the human muscle.

At the University of Texas at Dallas, Nanotech Institute scientists are working with nano sized cylinders. These nanotubes are made of graphite and conductive polymers and are powered by electricity.

Neural Interfaces
The first mechanical prosthetics were designed to replace missing body parts. The problem was that they offered only limited mobility. In 2001, technology enabled a computerized mechanical prosthesis with robotic, human-like movement. The next goal is to connect a robotic prosthesis directly to the nerve endings or to the brain, i.e., produce a neural interface. When successful, this will allow patients to better control the prosthetic device. These next generation products may be able to provide an individual with the ability to control devices that allow breathing, bladder and bowel movements.

There are several types of neural interfaces. These include electrooculogram (EOG), electromyogram (EMG), electroencephalogram (EEG), electrocardiogram (EKG), and neural electrodes. EOG technology obtains signals from eye movements with sensors that are in contact with the skin on a user's face.

Neural electrodes obtain signals directly from active neurons using electrodes. Neural electrodes provide a two-way data transmission between mind and machine. This technology is currently five to six years away from commercialization.

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