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. 2025 May 2;16(6):2210-2216.
doi: 10.1364/BOE.560412. eCollection 2025 Jun 1.

Label-free sensing technology of two Staphylococcus species based on a terahertz metasurface

Hui Zhong  1 , Jingle Li  1   2 , Jinghao Jiang  3 , Xunpei Xu  3 , Dongdong Zhang  1 , Liwei Song  1   4   5 , Rui Gao  3   6 , Ye Tian  1   4   7
Affiliations

Label-free sensing technology of two Staphylococcus species based on a terahertz metasurface

Hui Zhong et al. Biomed Opt Express. .

Abstract

Staphylococcus epidermidis (SE) and Staphylococcus aureus (SAU), comprising 50% of pathogenic bacteria in clinical blood isolates, demand precise detection for infection control. We present a label-free terahertz (THz) metasurface biosensor enabling simultaneous quantification and speciation of these Gram-positive pathogens. A tailored metasurface enhances THz wave-bacteria interaction through sharp resonance, creating quantitative correlations between resonance shifts and bacterial fluid dosage. Distinct linear regression slopes (SAU: 105.90 GHz/μL, SE: 45.14 GHz/μL) permit species differentiation, achieving specificity without biochemical labeling. This platform eliminates complex surface functionalization, reducing preparation time compared to ELISA-based methods while maintaining high sensitivity (theoretically 135.1 GHz/RIU, at a thickness of 3 μm, and experimentally 556 GHz/cell μm-2 (SAU) and 237 GHz/cell μm-2 (SE)). The technology's dual detection-differentiation capability, combined with its operational simplicity and cost-effectiveness, demonstrates transformative potential for clinical diagnostics and food safety monitoring, particularly in resource-limited settings requiring rapid pathogen screening.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Fig. 1.
Fig. 1.
Metasurface diagram. (a) No label sensing two staphylococci. The structural parameters of the unit: (b) top view and (c) side view. (d) microscopic image of the metasurface obtained.
Fig. 2.
Fig. 2.
Numerical simulation of transmission spectrum of the metasurface. (a) With the thickness of the analyte maintained at 3.0 μm, the refractive index is increased from 1.0 to 2.0. (b) With the refractive index of the analyte maintained at 1.6, the thickness is increased from 0.5 μm to 3.0 μm.
Fig. 3.
Fig. 3.
The measured transmission curves of atmosphere and bare metasurface. BG: Background. None: bare metasurface.
Fig. 4.
Fig. 4.
The actual measured metasurface transmission spectrum (dotted line) and corresponding fitting curve (solid line) under different bacterial fluid dosage of (a) SAU and (b) SE. (c) The dependent of frequency shift on the number of bacterial droplets with error bars.
See this image and copyright information in PMC

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