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Micro and Nano Systems Letters
https://doi.org/10.1186/s40486-026-00256-6
Rafita Erli Adhawiyah and Jungchul Lee
Abstract:
Heavy metal ions (HMIs), such as mercury (Hg), lead (Pb), cadmium (Cd), arsenic (As), and chromium (Cr), are a serious environmental issue due to their toxicity, bioaccumulation, and long-term persistence, making it necessary to develop sensitive and selective detection technologies. Laboratory-based methods, such as atomic absorption spectroscopy, provide high accuracy, but their point-of-need deployment is limited by their reliance on large equipment and complicated sample preparation. This review highlights the critical role of nanomaterial in sensing platforms in overcoming these limitations and advancements across electrochemical and optical detection techniques. The integration of nanomaterials-including carbon-based, metallic-based, silicon-based, and quantum dots-is shown to significantly enhance sensor performance through increased surface area, electron transfer efficiency, and plasmonic effects. Despite this progress, challenges such as matrix interference, ensuring signal reproducibility, and developing scalable fabrication methods remain. Future research will focus on developing hybrid, multiplexed, and antifouling sensor architectures integrated with digital technologies like the Internet of Things (IoT) to realize next-generation, ultra-sensitive HMIs monitoring platforms.
Fig:Electrochemical sensing techniques for HMIs detection.A. Voltammetric/Amperometric methods, B. Potentiometric method, and C. Conductometric method
MXene covered one dimensional plasmonic grating as analyte detector
Ali Hemmati, Soodabeh Nouri Jouybari, Saeed Mirzanejhad, Seyedeh Mehri Hamidi
Surface plasmon-based devices are widely used as highly sensitive optical sensing tools in diverse fields, including biological and chemical detection. The use of digital versatile discs (DVDs) as sensor substrates provides an attractive approach for developing surface plasmon resonance (SPR) sensors due to their easy availability, low cost, and nanoscale smooth surface. A silver coating on DVDs acts as the active metal layer and provides favorable plasmonic properties, although its sensitivity and optical stability remain limited. In this study, a two-dimensional (2D) material, MXene, was applied as a reinforcing layer on the silver-coated DVD surface to improve plasmonic performance. A pronounced polarization-dependent behavior is observed in the reflection spectra after MXene integration. This polarization-dependent response is advantageous for the design of compact and portable SPR sensing systems. The dependence of the spectra on the refractive index of the surrounding medium and the incident beam angle was also investigated.
Double Resonance Spectroscopy in Rb Vapor Cell of Atomic Clock via Synthesizer
Ali Mirzaei, Danial Cheraghian, Mahnaz Asadolah Salmanpour, Mohammad Mosleh,and Seyedeh Mehri Hamidi
ABSTRACT:
We aim to examine double resonance of Rb vapor cell via synthesizing the input 10 MHz frequency as standard atomic clock devices. For this purpose, we use the Voltage Controlled Oscillator onto the synthesizer and record double resonance between optical and microwave pumping. Our results show that the fabricated synthesizer, whose applied frequency is locked to a target frequency, can generate efficient coupling between these two main resonances in atomic media.
Fig. 1. (a) Fine and hyperfine structure of the Rb87 atom, illustrating the optical and microwave fields applied for double resonance. (b) Schematic diagram of the experimental setup used for the double resonance spectroscopy of Rb87 atoms, including the optical pumping configuration and the applied microwave field. (c) Block diagram of the frequency synthesizer, illustrating the main components responsible for generating, multiplying, and stabilizing the microwave output frequency.
Optical Route for Testosterone Hormone Sensing Exploiting Bloch Waves in One Dimensional Photonic Crystal
Arash Shirshahi, D. Cheraghian, M. Ghasemi, S. M. Hamidi, P. K. Choudhury
Bloch surface waves (BSWs) in periodic multilayer photonic crystals (PCs) were excited using a 635-nm laser for testosterone hormone detection employing the Kretschmann-Raether configuration. A 24-layer ZrO2-SiO2 PC served as the key dielectric sensing medium for the evanescent field interaction with testosterone molecules in blood plasma. Although SiO2 does not bind strongly to testosterone, it provides the necessary low-index component to achieve high contrast with ZrO2. The layer combinations are ideal for low optical loss in biosensing. A 20-μl mixture of phosphate buffered saline, testosterone, and blood plasma with the testosterone concentrations of 0.5, 1, 10, 100, and 200 mM were poured over the PC surface. The acceptable viscosity of this mixture helps adhere the BSW-based sensor to the BK7 prism coupler surface used in the experiment. The results of polarized reflected transverse magnetic waves indicate strong dependence on the angular shift. The lowest concentration (of 0.5 mM) was detected at an angle of approximately 51.2°, while the highest concentration (of 200 mM) was spotted at 51.7°. For concentrations <10 mM, the sensitivity of the studied BSW-based sensor was found to be nonlinear with the angular shift; higher concentrations, however, showed this feature to be linear.
Chitosan-PEDOT:PSS composite for Acetone Detection Using Plasmonic Image Sensor
Amir Reza Sadrolhosseini, Ali Bizhanifar, Ladan Akbari, S. Mehri Hamidi
Since acetone has more medical and industrial applications, the detection of acetone plays a significant role in indirectly measuring some quantities and controlling human safety in medical and industrial areas. In this research, a surface plasmon resonance image sensor was developed based on PEDOT:PSS to detect acetone. The gold nanoparticles have been fabricated using the laser ablation technique. Chitosan-PEDOT: PSS and chitosan-PEDOT: PSS-gold-nanoparticles composite were used to detect the pure acetone vapor form, and the response of the sensor was compared with the sensor’s response when the acetone was mixed with methanol and ethanol. Consequently, the variation in surface plasmon resonance image intensity for pure acetone was larger than the sensor’s response in the presence of methanol or ethanol and the sensor’s response is very insignificant when the sensing layer was contacted with pure methnol and ethanol.
Tunable scheme of phase modulation in Rabi resonance in a natural rubidium vapor cell
A.Mirazei, M. Sotoudeh, M. Asadolah Salmanpour, S. M. Hamidi
Precise measurement of phase-sensitive light–matter interactions in hot rubidium vapor cells plays a crucial role in advancing quantum technologies such as atomic clocks and quantum sensors. A central technique in this field is the “atomic candle,” which relies on Rabi resonances to stabilize and measure microwave field power. In most previous studies, Fast Fourier Transform (FFT) has been employed for signal analysis; however, FFT is vulnerable to noise and lacks the selectivity required for detecting weak signals. In this work, we introduce a new experimental setup in which a lock-in amplifier replaces FFT to perform phase demodulation. By employing synchronous detection at the second harmonic, the lock-in amplifier provides highly sensitive extraction of weak signals and strong noise rejection. Data acquisition was carried out using two regimes: slow modulation (<200 Hz) and fast modulation (>200 Hz). The results reveal that in the slow modulation regime the Rabi resonance amplitude increases with modulation frequency, indicating enhanced coupling strength, whereas in the fast modulation regime the amplitude decreases, consistent with the small-signal approximation. Furthermore, the measured Rabi frequency shows a linear dependence on the applied microwave power, in excellent agreement with theoretical predictions. These findings demonstrate that the lock-in amplifier offers a sensitive, accurate, and practical alternative to FFT for phase demodulation, providing valuable potential for applications in atomic clocks, quantum sensing, and precision spectroscopy.
Feasibility Study of Streptozotocin (STZ) Induced Cellular Changes Using Tamm Plasmon Polaritons in aOne-Dimensional Photonic Crystal
Mitra Bahrami, Seyedeh Mehri Hamidi
Magneto-plasmonic Lab, Laser and Plasma research Institute, Shahid Beheshti University, Tehran, Iran.
Doi:10.57647/pibm.2024.132408
Abstract:In this research, we design, simulate, and validate a label-free optical sensor that we use to monitor STZ-induced changes in neural stem cells. The basis of this sensor is the tamm plasmon polariton (TPP), which is excited at the interface of a one-dimensional photonic crystal and a thin layer of gold. In this work, we optimize the thickness of the gold layer and the measurement method by simulation based on the transfer matrix to increase the sensitivity of the sensor. After making the designed sensor, we cultured third-pass neural stem cells from the hippocampus of neonatal Wistar rats on it. After treating the cells with STZ, known to induce Alzheimer-like changes in vitro, the reflection spectra were recorded at selected time points (0, 17, and 30 h), illustrating the sensor’s potential for real-time monitoring of cellular responses. Finally, we compared and analyzed the simulation and experimental results. The proposed sensor, as a non-invasive, high-sensitivity, and real-time method, can be used to monitor Alzheimer’s-like processes in laboratory conditions.
Figure 1. (a) Schematic illustration of streptozotocin (STZ)-induced disruption of insulin signaling in neurons (Cruni et al., 2018), (b) Schematic diagram of the designed sensor architecture, showing the 1D photonic crystal composed of SiO2 and ZrO2 layers and a 40 nm gold layer, (c) Photograph of the fabricated TPP sensor, (d) Schematic of the angle-resolved reectance measurement setup, including the light source in wavelength of 635 nm, cylindrical prism, TPP sensor, and detector.
Bloch Surface Waves in a One-Dimensional Photonic Crystal as Doping Agent Sensor: Furosemide
Arash Shirshahi , Danial Cheraghian, Fateme Negahdari, Seyedeh Mehri Hamidi
Magneto-Plasmonic Laboratory, Laser and Plasma Research Institute, Shahid Beheshti University, Tehran, Iran
Doi:10.22034/ns.2025.2067330.1401
Abstract: Application of Bloch Surface Waves (BSWs) for detection of Furosemide using nanostructure Photonic crystals has been introduced in this paper. BSWs, as an electromagnetic phenomenon in periodic dielectric structures, were employed to detect various concentrations of the drug furosemide in distilled water. 24 layers photonic crystal composed of alternating ZrO₂ and SiO₂ layers was fabricated as a dielectric sensing medium, allowing the evanescent field generated at the terminal surface to interact with furosemide molecules. To excite the BSWs, the Kretschmann-Raether configuration was used, incorporating a 635 nm red laser source and a semi-cylindrical BK7 prism. A precise volume of 20 µL of furosemide solution at concentrations of 1, 1.5, 2, and 3.5 mM was deposited onto the surface of the photonic crystal. The reflectance of TM-polarized light was recorded within the angular range of 40° to 70°. Experimental results showed that the resonance angle shifted significantly with increasing furosemide concentration, specifically, the resonance angle changed from 51.941° in pure water to 52.245° at 1 mM, 52.549° at 2 mM, and 52.853° at 3.5 mM. The system demonstrated an approximately linear sensitivity to concentration changes within this range. These results highlight the potential of BSW-based photonic crystal sensors for the detection of doping-related drugs such as furosemide in clinical and sports medicine applications.
Thermoplasmonic enhanced detection efficiency by gold nanoparticles/ chlorophyll heterojunction on silicon nanowires
S. Valimohammadi, S. M. Hamidi and L. Rajaee
https://doi.org/10.1016/j.tsf.2025.140837
Abstract:
This study presents the development of a ternary heterojunction nanostructure for visible-light detection at 532 nm. Silicon nanowires (SiNWs) were grown using the metal-assisted chemical etching (MACE) method. The structure incorporates gold nanoparticles (Au NPs), synthesized via laser ablation (a fixed amount of S0: 1500 µL), which were combined with varying concentrations of chlorophyll-a (Chl-a) (S1: 1000 µL, S2: 1500 µL, S3: 2000 µL). Characterization techniques included SEM and AFM to confirm SiNWs morphology, UV-Vis spectroscopy to examine the optical properties of the Au/Chl-a combination, and current-voltage (I-V) measurements to evaluate the enhanced photodetector performance. Key findings demonstrated that plasmon-exciton dipole interactions effectively increase electron-hole pair separation via the formation of plexcitons. Furthermore, thermoplasmonic heating raised the temperature of the optimal sample (SiNWs@S2) to 51.6°C (compared to the baseline SiNWs@S0 temperature of 40.7°C), representing a 26.78% improvement. This system shows promising potential for high-performance optical sensing applications.
Figure 2: (a-c) Cross sectional scanning electron microscopy (SEM) micrographs of SiNWs fabricated at 30 min etching time in HF (40%)/AgNO3 (0.1 M)/H2O2(30%) solutions having a volume ratio of: 16:5:60 (top row),(d) 2D AFM image of SiNW,(e)Height profile and slope (f) I-V curve of P-type silicon wafers and SiNW at different voltages.