| Dopamine (DA) is the neurotransmitter produced by neurons in the nigrostriatal pathway of the basal ganglia motor loop in the brain. Degeneration of the DA producing neurons disturbs the smooth, coordinated function of body muscles, causes loss of memory and leads to neurological disorders like Parkinson's disease, Huntington's disease and Tourette's syndrome. Hence tremendous research is underway in the field of neuroscience to detect DA and animals are used as the models for humans in the laboratory. Carbon fiber and carbon paste electrodes are commonly used to detect DA in vivo in rat brains. However these electrodes have only a single detection site and do not allow simultaneous distinction of different neurotransmitters or detection of other electroactive compounds (such as, nitric oxide and oxygen) that are present along with DA in the brain. Therefore, there is a need to develop multi-site electrochemical probes. To serve this end, multi-site microelectrode devices were constructed using low temperature cofired ceramic (LTCC) as substrates and various conducting pastes that are compatible with LTCC processing as electrodes. The LTCC fabrication facilitates three dimensional structures to enable contact with the electrode at various levels in the probe. It is also relatively easy to fabricate as compared to silicon micro lithography and micromachining. The electrodes were composed of both carbon and gold pastes. In some cases, the surfaces were modified with a catalyst. The resulting electrode devices were characterized by electrochemical analysis of DA and model compounds. Scan rate studies and concentration studies were done to study the behavior of the electrodes at fast scans and to identify the detection limit of the device. Chip-based designs that are used for proof-of-concept studies and dagger-shaped designs that are suitable for insertion into the rat brain will be reported. It is anticipated that this technology will eventually contribute toward the real-time monitoring of DA under physiological conditions of the rat brain. |
