Towards a smart experimental arena for long-term electrophysiology experiments

Advancements in wireless power and data transmission have raised the prospects of using a variety of low power microelectronic devices such as biosensors, stimulators, and actuators in long-term uninterrupted electrophysiology experiments on small freely behaving animal subjects in large experimental arenas. This paper presents our progress towards developing such a system, called the EnerCage. This system includes a stationary unit for inductive power transmission through a scalable array of overlapping hexagonal coils, which are optimized using an accurate inductive link model and an iterative optimization process. Furthermore, the EnerCage system is equipped with an array of 3-D magnetic sensors and a smart tracking algorithm for non-line-of-sight positioning of the animal subject. EnerCage also has a small mobile unit, which is either attached to or implanted in the subject's body. This unit includes a magnetic tracer and an efficient power management block, which is capable of closed-loop regulated inductive power delivery to the experimental device(s) of interest. An early prototype of the EnerCage system with six coils has been presented here. The coil array achieves a power efficiency of 17.8% at the worst-case horizontal misalignment of 42 mm (half of the coil radius) at a coupling distance of 70 mm with the mobile unit coil of 20 mm in radius.