Direct Laser 3D Printing of Organic Semiconductor Microdevices for Bioelectronics and Biosensors.

Fabrication of conductive and bioactive microdevices has garnered tremendous attention in the emerging biomedical fields, particularly organic bioelectronics and biosensing. Direct laser 3D printing based on two-photon polymerization (TPP) has shown great promise in construction of well-defined and multi-functional microdevices. Herein, we present a novel photosensitive resin for fabrication of highly conductive and bioactive microstructures via TPP. This resin is based on poly(ethylene glycol) diacrylate that is doped with poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (organic semicoductor), and laminin (extracellular matrix protein) or glucose oxidase (biorecognition enzyme). We demonstrate the fabrication of hybrid microelectrodes, bioactive microstructures for cellular adhesion / spreading, and high-performance glucose biosensors. Clinical Relevance- Conductive and bioactive microelectronic devices based on the formulated resin can be utilized for neural recording / stimulation, tissue engineering, and biosensing applications.

Multiphoton Lithography of Organic Semiconductor Devices for 3D Printing of Flexible Electronic Circuits, Biosensors, and Bioelectronics.

In recent years, 3D printing of electronics have received growing attention due to their potential applications in emerging fields such as nanoelectronics and nanophotonics. Multiphoton lithography (MPL) is considered the state-of-the-art amongst the microfabrication techniques with true 3D fabrication capability owing to its excellent level of spatial and temporal control. Here, a homogenous and transparent photosensitive resin doped with an organic semiconductor material (OS), which is compatible with MPL process, is introduced to fabricate a variety of 3D OS composite microstructures (OSCMs) and microelectronic devices. Inclusion of 0.5 wt% OS in the resin enhances the electrical conductivity of the composite polymer about 10 orders of magnitude and compared to other MPL-based methods, the resultant OSCMs offer high specific electrical conductivity. As a model protein, laminin is incorporated into these OSCMs without a significant loss of activity. The OSCMs are biocompatible and support cell adhesion and growth. Glucose-oxidase-encapsulated OSCMs offer a highly sensitive glucose sensing platform with nearly tenfold higher sensitivity compared to previous glucose biosensors. In addition, this biosensor exhibits excellent specificity and high reproducibility. Overall, these results demonstrate the great potential of these novel MPL-fabricated OSCM devices for a wide range of applications from flexible bioelectronics/biosensors, to nanoelectronics and organ-on-a-chip devices.

Femtosecond Laser 3D-printing of Conductive Microelectronics for Potential Biomedical Applications.

Development of soft and conductive micro devices represents a demanding research topic in various biomedical applications, particularly organic bioelectronics. Among various fabrication methods, two-photon polymerization (2PP) using a wide range of photocurable inks is a promising 3D printing technique for construction of structures in submicron resolution. Herein, we introduce a novel conductive photosensitive resin by using poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and poly(ethylene glycol) diacrylate), and fabricate 3D conductive polymeric microstructures via 2PP. In the developed resin, presence of PEDOT:PSS significantly enhances the electrical conductivity of microstructures (~ 10 orders of magnitude).Clinical Relevance- Conductive microdevices based on the PEDOT:PSS-doped resin open new avenues in a broad range of biomedical research areas including neural interfaces, biosensors, and bioelectronics.