US researchers look to 3D-print organic electronics

A Texas research team has identified the possibility of utilising micro-scale organic electronics in the development of flexible electronics and bioelectronics, via multiphoton 3D-printers.

The team, led by Mohammad Reza Abidian, introduced a new photosensitive resin doped with an organic semiconductor material (OS) to fabricate "highly conductive 3D microstructures with high-quality structural features via MPL [multiphoton lithography]  process". 

To demonstrate the potential electronic applications based on the OS composite resin, the team fabricated various microelectronic devices, including a micro-printed circuit board and an array of microcapacitors. Their findings have been published online in the journal Advanced Materials. 

The experiment demonstrated that the fabrication process could be performed on glass and flexible substrate poly(dimethylsilosane). Moreover, the researched showed that loading as low as 0.5 wt% OS into the resin remarkably increased electrical conductivity of printed organic semiconductor composite polymer over 10 orders of magnitude.

“The excellent electrical conductivity can be attributed to presence of OS in the cross-linked polymer chains, providing both ionic and electronic conduction pathways along the polymer chains,” Abidian said.

Over the past few years, the 3D-printing of electronics has become a promising technology due to its potential applications in fields such as nanoelectronics and nanophotonics.

Within this area of research, 3D microfabrication technologies, multiphoton lithography is considered the state-of-the-art method, due to its excellent level of spatial and temporal control, and the versatility of photosensitive materials mostly composed of acrylate-based polymers/monomers or epoxy-based photoresists. Many fields, including tissue engineering, bioelectronics and biosensors could greatly benefit from these advantages.

The Texas team was also able to successfully incorporate bioactive molecules such as laminin and glucose oxidase into the OS composite microstructures (OSCMs), and conduct experiments to confirm that the bioactivity of laminin was retained throughout the entire MPL process, enhancing cell survival. 

“After seven days of culture, OS composite polymers did not induce cell mortality, with approximately 94 per cent cell viability compared to the control surfaces,” Abidian said.

The team put its findings into practice by fabricating a glucose biosensor using a maskless method based on MPL. The biosensor offered a highly sensitive glucose sensing platform with nearly 10-fold higher sensitivity compared to previous glucose biosensors, as well as excellent specificity and high reproducibility, demonstrating the potential of this technology for the future fabrication of bioelectronics and biosensors.

“We anticipate that the presented MPL-compatible OS composite resins will pave the path towards production of soft, bioactive, and conductive microstructures for various applications in the emerging fields of flexible bioelectronics, biosensors, nanoelectronics, organ-on-chips, and immune cell therapies,” Abidian said