Metamaterial biosensors have been extensively used to identify cell types and detect concentrations of tumor biomarkers. However, the methods for in situ and non-destruction measurement of cell migration, which plays a key role in tumor progression and metastasis, are highly desirable. Therefore, a flexible terahertz metamaterial biosensor based on parylene C substrate was proposed for label-free and non-destructive detection of breast cancer cell growth and migration. The maximum resonance peak frequency shift achieved 183.2 GHz when breast cancer cell MDA−MB−231 was cultured onto the surface of the metamaterial biosensor for 72 h. A designed polydimethylsiloxane (PDMS) barrier sheet was applied to detect the cell growth rate which was quantified as 14.9 µm/h. The experimental peak shift expressed a linear relationship with the covered area and a quadratic relationship with the distance, which was consistent with simulation results. Additionally, the cell migration indicated that the transform growth factor-β (TGF-β) promoted the cancer cell migration. The terahertz metamaterial biosensor shows great potential for the investigation of cell biology in the future.

Silicon photonic-based refractive index sensors are of great value in the detection of gases, biological and chemical substances. Among them, microring resonators are the most promising due to their compact size and narrow Lorentzian-shaped spectrum. The electric field in a subwavelength grating waveguide (SWG) is essentially confined in the low-refractive index dielectric, favoring enhanced analyte-photon interactions, which represents higher sensitivity. However, it is very challenging to further significantly improve the sensitivity of SWG ring resonator refractive index sensors. Here, a hybrid waveguide blocks double slot subwavelength grating microring resonator (HDSSWG-MRR) refractive index sensor operating in a water refractive index environment is proposed. By designing a new waveguide structure, a sensitivity of up to 1005 nm/RIU has been achieved, which is 182 nm/RIU higher than the currently highest sensitivity silicon photonic micro ring refractive index sensor. Meanwhile, utilizing a unique waveguide structure, a Q of 22,429 was achieved and a low limit of detection of 6.86 × 10⁻⁵ RIU was calculated.

Graphene-based photodetectors exhibit relatively low spectral absorption and rapid recombination of photogenerated carriers, which can limit their response performance. On the other hand, nanostructured lead sulfide (PbS) demonstrates a wide spectral absorption range from visible to near-infrared light. High-quality and evenly distributed PbS nanofilms were synthesized by chemical bath deposition and were applied to a graphene-PbS heterostructure photodetector. The heterostructure creates an inherent electric field that extends the lifetime of photogenerated carriers, leading to enhanced device response. We achieved a high-responsivity graphene-PbS photodetector by combining the high carrier mobility of graphene and the strong infrared absorption of PbS. The photodetector exhibits a responsivity of 72 A/W at 792 nm and 5.8 A/W at 1550 nm, with a response time of less than 20 ms. The optimized device features a broad spectral response ranging from 265 nm to 2200 nm.

Nanoimprint technology is powerful for fabricating nanostructures in a large area. However, expensive equipment, high cost, and complex process conditions hinder the application of nano-imprinting technology. Therefore, double-layer self-priming nanoimprint technology was proposed to fabricate ordered metal nanostructures uniformly on 4-inch soft and hard substrates without the aid of expensive instruments. Different nanostructure (gratings, nanoholes and nanoparticles) and different materials (metal and MoS₂) were patterned, which shows wide application of double-layer self-priming nanoimprint technology. Moreover, by a double-layer system, the width and the height of metal can be adjusted through the photoresist thickness and developing condition, which provide a programmable way to fabricate different nanostructures using a single mold. The double-layer self-priming nanoimprint method can be applied in poor condition without equipment and be programmable in nanostructure parameters using a single mold, which reduces the cost of instruments and molds.