Implantable microprobe with arrayed microsensors for combined amperometric monitoring of the neurotransmitters, glutamate and dopamine

An implantable, micromachined microprobe with a microsensor array for combined monitoring of the neurotransmitters, glutamate (Glut) and dopamine (DA), by constant potential amperometry has been created and characterized. Microprobe studies in vitro revealed Glut and DA microsensor sensitivities of 126 ± 5 nA μM−1 cm−2 and 3250 ± 50 nA μM−1 cm−2, respectively, with corresponding detection limits of 2.1 ± 0.2 μM and 62 ± 8 nM, both at comparable ∼1 s response times. No diffusional interaction of H2O2 among arrayed microelectrodes was observed. Also, no responses from the electroactive interferents, ascorbic acid (AA), uric acid (UA), DOPA (a DA catabolite) or DOPAC (a DA precursor), over their respective physiological concentration ranges, were detected. The dual sensing microbe attributes of size, detection limit, sensitivity, response time and selectivity make it attractive for combined sensing of Glut and DA in vivo.