The invention of organic semiconductors unravels new possibilities for fabricating electronic devices specially with 3D printing techniques. The development of flexible and wearable biosensing devices, based on organic electronics, has received a great amount of attention due to demands for affordable, non-invasive, and continuous monitoring of physiological parameters for healthcare and medical diagnostics. PEDOT:PSS based organic electrochemical transistors (OECTs) are ideal candidates for flexible and customizable biosensors which, due to the simple device structure and material stability, can be fabricated with 3D printing techniques.
In this study, we have 3D printed functional OECTs, using an Optomec Aerosol Jet 5X 3D printer with commercially available materials. These devices were assembled as follows: first, a Parylene C substrate was thermally deposited, then a gate electrode as well as the source and drain electrodes were printed with commercially available platinum and silver nanoparticle ink respectively, the channel was then printed using PEDOT:PSS ink, and finally the passivation layer was printed with commercially available UV-curable polymer that was cured in-situ. The printed OECTs with similar channel dimensions (W= 95 mm, W/L = 4, d=374 nm) have shown high peak transconductance (gm= 998.3 mS), low threshold voltage (0.51 V) and high current ON/OFF ratio (ID,ON/ID,OFF= 3.3x103).
Functionalization improves the capability of detecting a particular analyte. OECTs have been demonstrated as glucose sensors, which show electrical response to changes in glucose concentration levels. Expanding on this work, we have also conducted studies of surface immobilization of glucose oxidase (GOx), which is commonly used for glucose detection. We have conducted the functionalization by the standard technique of dip-coating and also implemented 3D printing of the GOx. Results from glucose measurement with no functionalization and with the dip-coated and 3D functionalized will be presented here.