Thirstrup Carsten, Nielsen Ole Stender, Lassen Mikael, Andersen Thomas Emil, Aslan Hüsnü
Danish Fundamental Metrology Kogle Allé 5, DK-2970 Hørsholm, Denmark.
Department of Clinical Microbiology, Odense University Hospital, J. B. Winsløws Vej 21, 2nd Floor, DK-5000 Odense, Denmark.
Sensors (Basel). 2025 Apr 11;25(8):2427. doi: 10.3390/s25082427.
Monitoring bacterial activity is essential for numerous scientific and industrial applications. However, current benchmark measurements, i.e., optical density (OD), exhibit a limited dynamic range and require transparent or translucent media. Conventional impedance spectroscopy involves direct electrode contact with the bacterial medium or biofilm, potentially perturbing the sample environment and compromising measurement fidelity. Moreover, many real-time methods rely on costly, specialized labware that limits scalability and versatility. Here, we introduce a non-contact impedance spectroscopy (NCIS) technique with customizable electrodes for off-the-shelf labware and show that the data collected from a KCl solution series agree well with the simplest electrolytic conductivity cell model solution, demonstrating the accuracy and simplicity of NCIS. As an example of bacterial activity monitoring, NCIS was performed in glass laboratory bottles and 24-well plates in which and cultures were inoculated into Brain Heart Infusion media, maintained at 37 °C. Comparative OD measurements acquired intermittently from the same media exhibited a strong correlation between NCIS and OD data, confirming reliability and reproducibility. The bacterial culture was verified by Raman spectroscopy assisted by machine learning. NCIS eliminates the risks of contamination and sample alteration, minimizing costs and operational complexity and providing a scalable, versatile solution for biological and chemical research.
监测细菌活性对于众多科学和工业应用至关重要。然而，当前的基准测量方法，即光密度（OD），动态范围有限，且需要透明或半透明介质。传统的阻抗谱需要电极与细菌培养基或生物膜直接接触，这可能会干扰样品环境并影响测量的保真度。此外，许多实时方法依赖于昂贵的专用实验室器具，这限制了可扩展性和通用性。在此，我们介绍一种具有可定制电极的非接触阻抗谱（NCIS）技术，适用于现成的实验室器具，并表明从氯化钾溶液系列收集的数据与最简单的电解电导率池模型溶液吻合良好，证明了NCIS的准确性和简易性。作为细菌活性监测的一个例子，在玻璃实验室瓶和24孔板中进行了NCIS实验，将大肠杆菌和金黄色葡萄球菌培养物接种到脑心浸液培养基中，保持在37°C。从相同培养基中间歇性获取的对比OD测量结果显示，NCIS和OD数据之间存在很强的相关性，证实了可靠性和可重复性。通过机器学习辅助的拉曼光谱对细菌培养物进行了验证。NCIS消除了污染和样品改变的风险，将成本和操作复杂性降至最低，并为生物和化学研究提供了一种可扩展、通用的解决方案。
