We develop metasurface-enhanced nanospectroscopy to reveal molecular fingerprints and biochemical dynamics that are difficult to resolve with conventional optical measurements. By engineering plasmonic resonances, nanoscale gaps, and light–matter interactions, we create sensitive optical interfaces for probing biomolecules and cell-derived signals. Our research combines plasmonic resonance energy transfer (PRET), hyperspectral imaging, and surface-enhanced Raman spectroscopy (SERS) to connect nanoscale optical responses with biological function.

Our multiplexed PRET platform uses pixelated metasurfaces with tailored scattering spectra across the visible range to probe molecular absorption signatures and electron-transfer dynamics in living cells. Complementary SERS approaches provide vibrational fingerprints of biomolecules, enabling analysis of secreted tau proteins from human cerebral organoids and investigation of the APOE–tau relationship. More recently, we have combined ultrasound-enhanced exosome secretion with antibody-free SERS profiling of exosomes from iPSC-derived cortical organoids, extending our spectroscopy toolkit for studying Alzheimer’s disease-associated molecular changes.

We develop metaphotonic molecular diagnostic platforms that convert light into heat for rapid and efficient nucleic acid amplification. By engineering highly absorbing nanostructures, we enable fast thermal cycling with compact optical sources, supporting the development of miniaturized PCR systems. Our research integrates optical absorber design, photothermal materials, and scalable fabrication to advance accessible point-of-care molecular testing. Our platforms span titanium nitride (TiN) metasurfaces and solution-processed MXene-based absorbers. We demonstrated a ring-shaped TiN meta-absorber fabricated over a large area using colloidal lithography, enabling 30 PCR thermal cycles within 3 minutes and 15 seconds. Building on this approach, we developed an all-solution-processed absorber incorporating Ti₃C₂Tₓ MXene, silica, and gold nanoparticles. This platform achieves approximately 98% light absorption without costly lithographic patterning and supports rapid photonic PCR using a compact 940 nm infrared LED. These complementary approaches demonstrate how nanophotonic design and materials engineering can improve both thermal performance and fabrication accessibility.

Single molecule fluorescence spectroscopy is at the heart of molecular biophysics research and the most sensitive biosensing assays. The growing demand for precision medicine and environmental monitoring requires the creation of miniaturized and portable sensing platforms. However, the need for highly sophisticated objective lenses has precluded the development of single molecule detection systems for truly portable devices.Here,we propose a dielectric metalens device of submicrometer thickness to excite and collect light from fluorescent molecules instead of an objective lens. The unprecedented sensitivity of the metalens opens up various biomedical applications in portable single molecule systems. Because of their extremely small size, the proposed metalens can be integrated with available miniaturized microscope solutions, e.g., smartphone microscopes and 3D-printed FCS platforms. Metalens structures are compatible with photonic chips making them viable candidates for integrating single molecule on-chip sensors for point-of-care testing.

Biological imaging techniques are indispensable for the exploration of biological processes, structures, and states. Advanced imaging techniques have been widely studied for various biological applications, such as diagnosis, biometrics, and fundamental biological research. As the importance of biological imaging has been highlighted, there has been an increased demand for advanced imaging techniques that are faster, wider, clearer, and more accurate. With multifunctional metasurfaces we are advancing biological imaging techniques such as super-resolution imaging, analog image processing, fluorescent imaging, photoacoustic imaging, medical imaging and biometrices. For example, the axially multifocal metalens can extend depth-of-field to enable 3D volumetric photoacoustic imaging for live organoid. We successfully monitor the melanogenesis in live brain organoids at various maturation stages and determine the distribution of neuromelanin content and its location in the organoid volumes. Since neuromelanin is selected as the target substance due to its key association with the pathology of Parkinson's Disease (PD), where the loss of dopaminergic neurons in the substantia nigra is closely correlated with decreased neuromelanin levels, we believe that our system can effectively monitor the progressive neurodegeneration observed in PD.

Microphysiological systems (MPS), including organoid-on-a-chip and organ-on-a-chip platforms, provide human-relevant models for investigating disease mechanisms and evaluating therapeutic responses. However, most conventional MPS rely on endpoint assays or indirect measurements, making it difficult to continuously monitor molecular signals from living three-dimensional tissues. We develop metaphotonic MPS by integrating human organoids, microfluidic control, and nanoplasmonic or metasurface biosensors into a unified platform. Engineered optical resonances enhance light–matter interactions and translate subtle biomolecular changes into measurable optical signals, enabling highly sensitive, label-free, and non-destructive monitoring of metabolites, neurotransmitters, secreted proteins, and other functional biomarkers. Our platforms are designed to connect precisely controlled drug administration with real-time molecular responses in living human-derived tissues. By reconstructing concentration–time profiles, we aim to quantify not only whether a treatment is effective, but also how rapidly, strongly, and persistently the tissue responds. This approach introduces dynamic molecular readouts into organoid-based drug screening and offers new opportunities for disease modeling, pharmacological profiling, and toxicity assessment.

Quantum mechanical perspective on light-matter interactions with specifically designed optical cavity, or cavity quantum electrodynamics, can offer insight into the relationship between atomic states of matter and electromagnetic modes in optical cavity.  We are witnessing that the peculiar hybridized energy state between atom and photon, or partial matter and partial light at the same time, can be detected using general optical microscope at room temperature, though, relatively few applications of strong coupling effects have been reported. We develop quantum metasurfaces for plexcitonic and polaritonic strong coupling effects in chemical and biomedical applications. The strong coupling effect can be utilized as a tool to modify chemical reaction landscapes using the vibrational state of molecule and hot electron of plasmon in chemistry. In addition, strong coupling-induced quantum plasmonic biosensor not only can detect quantum coherence effects, but also improve detection sensitivity beyond the limit of classical sensors.