Institute of Physical Chemistry , Clausthal University of Technology , 38678 Clausthal-Zellerfeld , Germany.
Anal Chem. 2019 Nov 19;91(22):14476-14481. doi: 10.1021/acs.analchem.9b03204. Epub 2019 Oct 29.
Electroactive biofilms are intensely studied not only for energy conversion and electrosynthesis, but also as sensing systems. The electrical current produced by the layer is largely proportional to the rate of metabolism and therefore decreases when the biofilm experiences adverse environmental conditions. Acoustic measurements may complement this approach. The layer's softness can be inferred from shifts of resonance frequency and resonance bandwidth of a quartz crystal microbalance (QCM) contacting these layers. The layer's softness responds to the environment. Both negative potentials of the electrode (the equivalent of "suffocation") and lack of nutrient supply (the equivalent of "starvation") were studied. For comprehensive analysis, torsional resonators operating on three different modes of vibration are suited best. Such data can be fitted with a viscoelastic model, leading to a quantitative estimate of the shear modulus. On a more empirical level, one might also use the ratio of the shift in bandwidth to the negative shift in frequency as an indicator of stress. For ease of operation, one might even replace the torsional resonators with thickness-shear resonators.
电活性生物膜不仅在能量转换和电合成方面受到广泛研究，还作为传感系统受到关注。该层产生的电流与代谢率成正比，因此当生物膜经历不利的环境条件时，电流会减小。声学测量可以对此方法进行补充。通过石英晶体微天平（QCM）与这些层接触时共振频率和共振带宽的偏移，可以推断出该层的柔软度。该层的柔软度对环境有响应。电极的负电位（相当于“窒息”）和缺乏营养供应（相当于“饥饿”）都进行了研究。为了进行全面分析，最好使用以三种不同振动模式运行的扭转谐振器。可以使用粘弹性模型对这些数据进行拟合，从而对剪切弹性模量进行定量估计。在更经验性的层面上，也可以使用带宽偏移与频率负偏移的比值作为应力的指标。为了便于操作，甚至可以用厚度剪切谐振器代替扭转谐振器。
