Heidi B. Martin

Our research focuses on engineering of materials for biomedical and biochemical applications, with emphasis on implantable electrochemical devices including neurosensors and neural/muscle stimulators. We want to generate smaller, faster, more robust and versatile sensors and stimulators, and use these devices to aid in expanding medical knowledge and advancing clinical therapies. This will require improved microfabrication/nanofabrication procedures that still permit control of the electrode surface chemistry to maintain device performance. We will also need to understand and control the interaction of the material surface with the biological/biochemical environment. Electrochemical studies of mediated and direct electron transfer will aid in fundamental understanding of the electrochemically-based biosensor surfaces.

Diamond-based electrodes are a promising technology for biomedical research. We are currently developing conductive, diamond-based materials as superior electrodes for extracellular, neurological sensing and stimulation. Diamond provides a unique opportunity to integrate stimulation and sensing in the same device. We hypothesize that diamond electrodes will provide real-time neurological sensing capability, with greatly improved sensitivity, selectivity and stability, as well as an expanded potential range of operation over present materials. Diamond may expand neural stimulation capabilities by avoiding side reactions that lead to tissue damage and by providing long-term stability. These advantages will be applicable to a broad variety of neurological systems. We are exploring these capabilities by focusing on extracellular sensing of "chemical messengers" of the brain and nervous system, dopamine, adenosine, and serotonin, and evaluation of neural stimulation, using our diamond technology toward addressing specific neuromodulatory questions.

Neurotransmitters play key roles in normal brain function and are linked to a number of neurological and psychiatric disorders including Alzheimer's, Parkinson's and Huntington's diseases, as well as depression, epilepsy, drug/alcohol dependence and schizophrenia. It is hoped that we can improve our understanding of the relationship between neurotransmission and human behavior and illness. Monitoring and manipulating the concentration of these neurochemicals in real time provides a direct way to understand the processes that regulate and control communication between neurons. Incorporation of diamond into implantable devices could translate into a significant expansion of existing in vivo sensing and stimulation capabilities, providing long-term devices, not just for neural applications, but for a variety of other biological systems.