Tunable metamaterial devices have experienced explosive growth in the past decades, driving the traditional electromagnetic (EM) devices to evolve into diversified functionalities by manipulating EM properties such as amplitude, frequency, phase, polarization, and propagation direction. However, one of the bottlenecks of these rapidly developed metamaterials technologies is limited tunability caused by the intrinsic frequency‐dependent property of exotic tunable material. To overcome such limitation, the microelectromechanical system (MEMS) enabling micro/nanoscale manipulation is developed to actively control “meta‐atom” in terahertz and infrared region, which brings frequency‐scalable tunability and complementary metal‐oxide‐semiconductor‐compatible functional meta‐devices. Beyond tunability, novel chemical sensing platforms of molecular identification and dynamic monitoring of the biochemical process can be achieved by integrating micro/nanofluidics channels with metamaterial resonators. Additionally, incorporating metamaterial absorbers with MEMS resonators brings another research interest in MEMS zero‐power devices and radiation sensors. Furthermore, moving from 2D metasurfaces to 3D metamaterials, enhanced EM properties like novel resonance mode, giant chirality, and 3D manipulation reinforce the application in biochemical and physical sensors as well as functional meta‐devices, paving the way to realize multi‐functional sensing and signal processing on a hybrid smart‐sensor microsystem for booming healthcare, environmental monitoring, and the Internet of Things applications.

The terahertz spectral region has received tremendous attention for label free chemical and biological sensing, due to the presence of molecular fingerprints, low energy characteristics, and remote sensing capabilities. However, a major hindrance for the realization of a high performance terahertz bio-chemical sensor comes from the large absorption of terahertz waves by aqueous solution. Here, we overcome this limitation by confining the analyte-aqueous solution in a nanovolumetric fluidic chamber, integrated on metamaterial resonant cavities. The metamaterial resonators confine electromagnetic fields in extremely subwavelength space and hence allow for the enhanced interaction between the nanovolumetric analyte-aqueous solution and terahertz waves, while minimizing the absorption loss. We compare the sensing performance of split ring resonator and Fano resonator systems as metamaterial resonators. As a demonstration of chemical sensing, three alcoholic solutions with different concentrations were measured. Selective adenosine triphosphate (ATP) sensing capability was examined through ATP aptamer functionalization on gold metamaterials, where a decrease in the transmittance value was observed as the ATP concentration increased. The proposed sensing approach has the potential to be an effective tool for molecular analysis through exploiting the advantages offered by low energy terahertz, subwavelength metamaterial resonators and nanofluidic technologies.

We experimentally demonstrate the integration of a microfluidic trap array on top of metamaterial resonators for size selective trapping and remote sensing of microparticles. A split-ring resonator (SRR) design supports strongly confined electric field in the capacitive split gap at the fundamental inductive-capacitive resonance mode. The tightly confined electric field in the SRR gap forms a hot-spot that has become an enabling platform for sensing applications. Here, we extend the concept of metamaterial sensing to "trapping and sensing" by fabricating trapezoidal shaped structures near the split gap that enables trapping of microparticles in the split-gap region of each SRR. The proposed microfluidic metamaterial sensor enables sensing of different refractive index microparticles in terms of change in the transmitted amplitude and resonance frequency of the fundamental resonance mode operating in the terahertz spectral region. The proposed approach exploits the advantages offered by microfluidics, metamaterials, and terahertz technologies to form an ideal platform for ultra-sensitive, label-free, remote, and non-destructive detection of micro-substances.