Planar arrays of electrode are limited when studying acute slices of brain tissue as they only monitor signals from the damaged layers of the neural tissue. Arrays of micro-needles can penetrate past this damaged layer and monitor the activity of neurons within the neural substrate.
This “bed-of-nails” type electrode array is able to penetrate brain tissue and record extracellular single-unit activity at high resolution (60 microns) and is being extended to cover ~2mm2 of tissue.
Dr Deborah Gunning leads this work and is funded through a prestigious Royal Academy of Engineering Fellowship.
For an example of this technology, please read the paper "Dense arrays of micro-needles for recording and electrical stimulation of neural activity in acute brain slices".