  As essential components in intelligent systems, printed soft electronics
(PSEs) are playing crucial roles in public health, national security, and
economics. Innovations in printing technologies are required to promote the
broad application of high-performance PSEs at a low cost. However, current
printing techniques are still facing long-lasting challenges in addressing the
conflict between printing speed and performance. To overcome this challenge, we
developed a new corona-enabled electrostatic printing (CEP) technique for
ultra-fast (milliseconds) roll-to-roll (R2R) manufacturing of binder-free
multifunctional e-skins. The printing capability and controllability of CEP
were investigated through parametric studies and microstructure observation.
The electric field generation, material transfer, and particle amount and size
selecting mechanisms were numerically and experimentally studied. CEP printed
graphene e-skins were demonstrated to possess outstanding strain sensing
performance. The binder-free feature of the CEP-assembled networks enables them
to provide pressure sensitivity as low as 2.5 Pa, and capability to detect
acoustic signals of hundreds of hertz in frequency. Furthermore, the CEP
technique was utilized to pattern different types of functional materials
(e.g., graphene and thermochromic polymers) onto different substrates (e.g.,
tape and textile). Overall, this study demonstrated that CEP can be a novel
contactless and ultrafast manufacturing platform compatible with R2R process
for fabricating high-performance, scalable, and low-cost soft electronics.
