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Neurotransmitters are used by the nervous system to transmit messages between neurons. The abnormal levels of the neurotransmitters may lead to neurological disorders. It is very important to monitor their levels in patients. Herein, we report a polymer nanostructured electrode-enabled electrochemical sensing microchip for detecting dopamine and serotonin. The nanostructures on the electrode can enhance the surface area of the electrode dramatically. As a result, the measured electrical signals increased in comparison with those of an electrochemical sensor with an electrode of a flat surface. It has been found that this microchip can detect neurotransmitters with a level as low as ~120 nM with high specificity and can be used to monitor the dopamine and serotonin in a mixed sample successfully in both static and dynamic conditions. Finally, the real-time measurements of dopamine released from N27-A dopaminergic neural cells using the microchip have been demonstrated. 

We report a method to fabricate silicon micro–nanostructures of different shapes by tuning the number of layers and the sizes of self-assembled polystyrene beads, which serve as the mask, and by tuning the reactive ion etching (RIE) time. This process is simple, scalable, and inexpensive without using any sophisticated nanomanufacturing equipment. Specifically, in this work, we demonstrate the proposed process by fabricating silicon micro- or nanoflowers, micro- or nanobells, nanopyramids, and nanotriangles using a self-assembled monolayer or bilayer of polystyrene beads as the mask. We also fabricate flexible micro–nanostructures by using silicon molds with micro–nanostructures. Finally, we demonstrate the fabrication of bandage-type electrochemical sensors with micro–nanostructured working electrodes for detecting dopamine, a neurotransmitter related to stress and neurodegenerative diseases in artificial sweat. All these demonstrations indicate that the proposed process provides a low-cost, easy-to-use approach for fabricating silicon micro–nanostructures and flexible micro–nanostructures, thus paving a way for developing wearable micro–nanostructures enabled sensors for a variety of applications in an efficient manner.