Chiral metasurfaces are capable of generating a huge
superchiral
field, which has great potential in optoelectronics and biosensing.
However, the conventional fabrication process suffers greatly from
time consumption, high cost, and difficult multilayer alignment, which
hinder its commercial application. Herein, we propose a twisted stacking
carbon-based terahertz (THz) chiral metasurface (TCM) based on laser-induced
graphene (LIG) technology. By repeating a two-step process of sticking
a polyimide film, followed by laser direct writing, the two layers
of the TCM are aligned automatically in the fabrication. Laser manufacturing
also brings such high processing speed that a TCM with a size of 15
× 15 mm can be prepared in 60 s. In addition, due to the greater
dissipation of LIG than that of metals in the THz band, a giant circular
dichroism (CD) of +99.5 to −99.6% is experimentally realized.
The THz biosensing of bovine serum albumin enhanced by the proposed
TCMs is then demonstrated. A wide sensing range (0.5–50 mg
mL–1) and a good sensitivity [ΔCD: 2.09% (mg
mL–1)−1, Δf: 0.0034 THz (mg mL–1)−1] are
proved. This LIG-based TCM provides an environment-friendly platform
for chiral research and has great application potential in rapid and
low-cost commercial biosensing