Development of a Controllably Homogenous Conductive Ballistic Gelatin as a Realistic Spinal Cord Phantom

In this paper, we explore a moldable, conductive gelatin-based phantom that provides an average impedance close to that of the spinal cord tissues possible. Such phantoms can be employed to validate spinal cord electrodes recordings and data collection in preclinical stimulation tests, where voltage or current pulses are applied to paralyzed muscles and aid rehabilitation. By using phantoms, some surgery procedures will be eliminated, and a large number of quick tests will become feasible. In this research, ballistic gelatin was chosen as the phantom's primary foundation because it is low-cost, easy-to-use, simple-to-shape, and also can provide a conductivity range similar to that of spinal cord tissue. Doping Sodium chloride (NaCl) is used to modify the ions concentration in the gelatin-based phantom and significantly change the conductivity of the solution. So, the phantom's conductivity can be easily controlled, making it suitable for a range of applications based on the acquired conductivity. The molds were designed using AutoCAD software to be made using a 3D printing technique resulting in similar samples, proper for reliable comparison. We used Ag/AgCl dry electrodes to connect the samples to a designed low noise electrical circuit to measure the phantom impedance as a function of frequency. Then samples with similar conductivity to that of spinal cord tissue were chosen as the primary material for spinal cord phantom.