3D Printed Dopamine Biosensor

Patients affected by neurological diseases, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), Dementia, and Schizophrenia, exceed 100 million people worldwide. Currently, no specific cure or therapy is available for suppressing such diseases. Current treatments only slow down the deterioration of the patients’ health, increasing their quality of life. This can be done through lifelong medical therapies, which include pharmacological treatments, physiotherapy and, in some cases, surgical procedures. These neurological diseases are associated with a dysfunction of the dopamine system. Electrochemical sensors have been widely tested for detecting dopamine, achieving high sensitivity by exploiting the extraordinarily high amplification ability of organic electrochemical transistors (OECTs). Here, we report the development of functional inks for 3D printing the OECTs components on a thin parylene substrate (< 4 µm). The electrical connections are realized using graphene oxide (GO) and carbon nanotubes (CNT) blend. The channel area is defined using 3D-printable PEDOT:PSS formulations, optimized to promote internal ion mobility. Finally, we print a PDMS formulation to insulate the electrical connections and define the channel area. These printed OECTs show excellent electrical and mechanical properties. We demonstrate dopamine biosensing with selective sub-µM detection through the optimization of the gate materials and geometry. In addition, the use of 3D-printing systems allows the development of microfluidic systems, that combined with the 3D printed OECTs, enable a wearable system capable of real-time dopamine detection on human skin.