Acute head trauma can cause disability and death without prompt diagnosis and treatment. The methods of choice for such diagnosis are x-ray CT or MRI, but these systems are costly and lack portability. Blood has an electrical conductivity and a dielectric permittivity about 50 to 100% higher than that of healthy brain tissue, depending on the excitation frequency. This suggests that an entirely non-contact technique for detecting bleeding in the brain (hematoma) could be based on a magnetic induction measurement that responds to anomalous changes in the conductivity between the skull and dura. One possible design of such a sensor would consist of concentric transmitting and receiving coils in close proximity to the head, but not touching. If the frequency is swept over a suitable range, then a one-dimensional profile of conductivity as a function of depth could be generated by exploiting the electromagnetic skin effect. The advantages of this approach over near-infrared spectroscopy include the non-contact nature of the measurement and the possibility of using a conductivity profile to delineate the dimensions of the hematoma. A conductivity sensor could be designed to be portable, compact and relatively inexpensive. A prototype sensor suitable for testing on tissue phantoms will be developed in Phase I
