13. Neurostimulation Design from an Energy and Information Transfer Perspective

Neurostimulation—defined as electrical charge delivery for the purpose of affecting the behavior of nervous tissue—is one of the fastest growing applications in biomedical engineering. In the United States alone, neurostimulation products represented a $628 million market in 2006 with an expected annual growth rate of 20% [1]. Example applications include neurostimulation for pain control, incontinence, hearing loss, epilepsy and essential tremor. Even more exciting for engineers, researchers and venture capitalists are the nascent and under-developed applications of neurostimulation—particularly neurostimulation to restore function lost to neurological diseases or injury. At the heart of any such system is a circuit which drives neural tissue with electricity. An example radiograph showing the key elements of a neuromodulation system is shown in Fig. 13.1 these elements include the energy source, neurostimulation circuitry, mechanical packaging and stimulating electrodes. All neuromodulation systems have these general elements.