Inkjet-Printing of PEDOT:PSS for Bioelectronics

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been considered as one of the promising soft materials for emerging bioelectronic devices. There is increasing interest in the use of drop-on-demand inkjet printing as an additive manufacturing process. This talk presents the rheological properties, inkjet processes and bioelectronic applications of the polymer-containing printable ink. We show that the aqueous solution of PEDOT:PSS is strongly shear-thinning, and discuss how it can produce satellite-free inkjets. Furthermore, we characterize the rheological properties of a crosslinker (3-glycidyloxypropyl) trimethoxysilane-containing PEDOT:PSS at high frequencies, and investigate how the interactions of the polymers in the solution even at room temperature affect printability. Based on the optimized ink formulation and printing process, we demonstrate a technique to inkjet-print thin-film resistors of PEDOT:PSS on plastic which enables us to achieve five orders of magnitude in resistance value with high repeatability, while the feature size of the resistors remains unchanged. Finally, we present inkjet-printed organic voltage amplifiers by integrating active and passive electrical components on a single, highly flexible substrate for in vivo brain activity recording. Drop-on-demand printing facilitates fine-tuning of the voltage amplification properties while monolithic integration of the printed circuit achieves significant noise reduction. Finally, we validate the conformable brain-integrated organic voltage amplifiers as electrocorticography devices in a rat in vivo model, showing their ability to record local field potentials in anaesthetized animals.