A STUDY OF PROPOSED NEURAL EXCITATION BY INTERACTION OF ULTRASONIC AND ELECTROMAGNETIC ENERGY,
Abstract
A neural stimulation system is proposed exploiting the low frequency response of neurons to an excitation potential. Ultrasonic and electromagnetic energy interact in electrolytic solutions due to conductivity variations caused by the ultrasonic pressure waves in the solution. The potential of largest magnitude resulting from the interaction has a frequency equaling the sum and difference of the ultrasonic and electric field frequencies. The frequency of the applied field is chosen to exceed the response time of the neurons, preventing excitation; the frequency of the induced potential, being the difference of two frequencies, can be constrained to fall within the response time of neurons and produces excitation. The shape and position of the volume containing the excitation potential is controlled by focusing the ultrasonic waves to high intensity in a small volume. The system is modeled both electrically and ultrasonically by a simple salt solution similar to body interstital fluids. The relevant field equations for a conducting solution are applied to the model; the conductivity function contains a small time varying perturbation which is a linear function of the local dynamic pressure due to a focused ultrasonic source. The resultant nonlinear, partial differential equation is solved by an assumed power expansion of the solution in applying perturbation theory. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1968
- Accession Number
- AD0672002
Entities
People
- Elmer L. Hixson
- James D. Wolfe
Organizations
- University of Texas at Austin