This study investigated a novel multi-electrode-array (MEA) design capable of long-term and highly selective recordings of axonal signals using PDMS microtunnels. We successfully grew neurons in culture so that only axons extended through narrow (10 µm wide by 3 µm high) and long (750 µm) microtunnels under which multiple electrodes were integrated. This permitted the recording of relatively large (up to 200 µV) electrical signals, including the propagation speed and direction of these travelling action potentials. To further demonstrate the operation of the device as a diagnostic tool for drug screening assays, the drug mepivacaine was applied in washout experiments. Here, we identified significant changes in mean spiking rate and conduction velocity.