Fabrication and testing of a novel all-diamond neural probe for chemical detection and electrical sensing applications

Fabrication and testing of all-diamond probes for neural applications is reported for the first time. Instead of commonly used silicon, undoped polycrystalline diamond (poly-C) with resistivity of ~10⁵ Omegacm was chosen as the structural material of the probe. In addition, highly boron-doped (resistivity of ~10^-3 Omegacm) poly-C film was used as the electrode material due to its excellent electrochemical properties and resistance to chemical attack. The diamond probe consists of 8 electrode sites with diameters ranging from 20 to 150 mum. The measured electrochemical potential window of the poly-C electrode was approximately -0.8 to 1.4 V in 1 M KCl. Initial measurements of electrochemical detection of a neurotransmitter called norepinephrine (NE) are very encouraging.