Recently, Professor Wang Yiping's team from the School of Physics and Optoelectronic Engineering at Shenzhen University published a research paper titled "An Optical Fiber-Based Nanomotion Sensor for Rapid Antibiotic and Antifungal Susceptibility Tests" in the internationally renowned nanotechnology journal "Nano Letters" (SCI Q1, Nature Index journal, impact factor 10.8), in the form of a cover article. The paper introduces a novel ultra-sensitive nanovibration sensor based on optical fibers. By utilizing microcantilevers fabricated via femtosecond laser direct two-photon polymerization at the endface of an optical fiber, this sensor is employed for rapid antibiotic and antifungal susceptibility tests. It significantly enhances the testing speed and achieves miniaturization and simplification of the experimental setup. Professor Liao Changrui from Shenzhen University and Dr. Zhou Jiangtao from École Polytechnique Fédérale de Lausanne (EPFL) are co-first authors of the paper, while Professor Wang Yiping from Shenzhen University, Professor Liao Changrui from Shenzhen University, Professor Sandor Kasas from EPFL, and Dr. Zhou Jiangtao from EPFL are co-corresponding authors.

Figure 1. Schematic Diagram of the Fiber Optic-Based Nanovibration Sensor

In recent years, the widespread misuse of antibiotics has led to the emergence of antimicrobial resistance in microorganisms, gradually becoming a global public health concern. One important method to mitigate its spread is through antimicrobial susceptibility testing to diagnose resistant bacteria. However, the main challenges of current susceptibility testing methods are slow testing speeds and low levels of parallel testing. In contrast to traditional methods that may take several hours or even weeks, our fiber optic-based ultra-sensitive nanovibration sensor can identify resistant microorganisms within 1-3 hours, enabling the determination of the most suitable drugs against specific pathogens. Compared to the latest atomic force microscope (AFM)-based ultra-sensitive nanovibration sensors, our sensor achieves similar testing speeds while being highly miniaturized, offering great potential for future integration and parallel testing.

In this study, we propose a fiber optic-based nanovibration sensor, where the principle lies in the dynamic interference changes of a Fabry–Pérot (FP) interferometer composed of the fiber optic endface and a cantilever beam when the biological cantilever vibrates. The core of its sensitive testing is the fabrication of flexible 3D printed highly sensitive cantilever beams using two-photon polymerization (2PP) technology. We implement 2PP printing in the vertical direction to achieve thinner cantilevers, with a final thickness of around 1 micron. Additionally, the relatively lower power of femtosecond laser and the relatively faster scanning speed during the polymerization process result in lower inherent stiffness related to the Young's modulus of the polymerized structure, thereby increasing the spring constant and detection sensitivity of the cantilever beams. The spring constant of the cantilever beams is as low as approximately 0.3 N/m, comparable to commercial silicon nitride AFM cantilevers. As a proof-of-concept prototype, we demonstrate that this fiber optic-based nanovibration sensor exhibits excellent performance in real-time sensitivity testing of Escherichia coli and Candida albicans against antibiotics and antifungal drugs respectively, detecting nanoscale or sub-nanoscale cantilever vibrations induced by their metabolic activities. This nanovibration sensor strategy, which combines rapid response and parallelization advantages, may propel the technology to become the next generation of nanovibration sensors, applicable for large-scale and rapid antimicrobial susceptibility testing, as well as other technological and biomedical applications.

Figure 2. Schematic Diagram of Laser Processing for Fiber Optic-Based Nanovibration Sensor

Figure 3. Nanoactivity Detection of Escherichia coli Sensitivity to Ampicillin Using Fiber Optic Nanovibration Sensor

This research was supported by the National Excellent Youth Science Foundation and the Guangdong Province International Science and Technology Cooperation Project.

Original paper link:https://pubs.acs.org/doi/10.1021/acs.nanolett.3c03781?ref=pdf