Recent progress in ultrafast spectroscopy and semiconductor technology is enabling unique applications in screening, detection, and diagnostics in the Terahertz (T-ray) regime. The promise of efficaciously operation in this spectral region is tempered by the lack of devices that can spectrally analyze samples at sufficient temporal and spatial resolution. Real-time, multispectral T-ray (Mul-T) imaging is reported by designing and demonstrating hyperspectral metamaterial focal plane array (MM-FPA) interfaces allowing multiband (and individually tunable) responses without compromising on the pixel size. These MM-FPAs are fully compatible with existing microfabrication technologies and have low noise when operating in the ambient environment. When tested with a set of frequency switchable quantum cascade lasers (QCLs) for multicolor illumination, both MM-FPAs and QCLs can be tuned to operate at multiple discrete THz frequencies to match analyte "fingerprints." Versatile imaging capabilities are presented, including unambiguous identification of concealed substances with intrinsic and/or human-engineered THz characteristics as well as effective diagnosis of cancerous tissues without notable spectral signatures in the THz range, underscoring the utility of applying multispectral approaches in this compelling wavelength range for sensing/identification and medical imaging.

Precise patterning of biomaterials has widespread applications, including drug release, degradable implants, tissue engineering, and regenerative medicine. Patterning of protein-based microstructures using UV-photolithography has been demonstrated using protein as the resist material. The Achilles heel of existing protein-based biophotoresists is the inevitable wide molecular weight distribution during the protein extraction/regeneration process, hindering their practical uses in the semiconductor industry where reliability and repeatability are paramount. A wafer-scale high resolution patterning of bio-microstructures using well-defined silk fibroin light chain as the resist material is presented showing unprecedent performances. The lithographic and etching performance of silk fibroin light chain resists are evaluated systematically and the underlying mechanisms are thoroughly discussed. The micropatterned silk structures are tested as cellular substrates for the successful spatial guidance of fetal neural stems cells seeded on the patterned substrates. The enhanced patterning resolution, the improved etch resistance, and the inherent biocompatibility of such protein-based photoresist provide new opportunities in fabricating large scale biocompatible functional microstructures.

Silk protein fibres produced by silkworms and spiders are renowned for their unparalleled mechanical strength and extensibility arising from their high-β-sheet crystal contents as natural materials. Investigation of β-sheet-oriented conformational transitions in silk proteins at the nanoscale remains a challenge using conventional imaging techniques given their limitations in chemical sensitivity or limited spatial resolution. Here, we report on electron-regulated nanoscale polymorphic transitions in silk proteins revealed by near-field infrared imaging and nano-spectroscopy at resolutions approaching the molecular level. The ability to locally probe nanoscale protein structural transitions combined with nanometre-precision electron-beam lithography offers us the capability to finely control the structure of silk proteins in two and three dimensions. Our work paves the way for unlocking essential nanoscopic protein structures and critical conditions for electron-induced conformational transitions, offering new rules to design protein-based nanoarchitectures.