Design and fabrication of a wearable device for early stage detection of Parkinson's disease.

In recent years, the demand for small electronic sensors able to monitor biological signals is increasing. This is due to the large possibilities offered by these devices, like the ability to sense small variations in the concentration of an analyte, record it in time and then visualize a change that could be indicative of a pathological state. The goal of this thesis is an early stage detection of Parkinson’s disease, one of the most widespread neurological disorders in the world. Since there is not currently a screening method, there is a high request for a standardized, repeatable and robust test able to sense if the patient shows early signs of the disease. This can be achieved through the measurement of the alpha-synuclein protein level in the skin, since when overproduced, it constitutes a biomarker of the disease. During this work, two different kinds of devices were completely designed, fabricated and tested to reveal this protein. The first one is a patch that should be attached to the back of a patient to make a mixed analysis of sweat and sebum compositions. It is a wearable and non-invasive tool, made of bio compatible materials like polyethylene terephthalate (PET) and polydimethylsiloxane (PDMS). PET is a flexible material used as substrate to accommodate two different groups of sensors, the organic electrochemical transistors (OECT) and the electrochemical electrodes. Different optimizations made it compatible with the most traditional microfabrication techniques, like chemical vapor deposition (CVD), photolithography and direct writing. PDMS constitutes the microfluidic layer, responsible for the transport of sweat from the skin to the OECT. The second device is instead a rigid multi analytic platform fabricated starting from a 4-inch silicon wafer as substrate, patterned with gold OECT using the conventional photolithographic techniques. Depending on the kind of antibodies used during the functionalization of the gate, the device can reveal the presence of proteins related to different pathologies, including alpha-synuclein. The liquid is contained through PDMS chambers. Two different designs are proposed, one with an extended gate and the other having just a single common gate. In conclusion, all the devices are tested to show their electrical characteristics.