Blake-Coleman B C, Hutchings M J, Silley P
Centre for Applied Microbiology and Research, Porton Down, U.K.
Biosens Bioelectron. 1994;9(3):231-42. doi: 10.1016/0956-5663(94)80126-6.
The frequency/amplitude effect of various microorganisms exposed to periodic (time varying) electric fields, when proximate to immersed electrodes, has been studied using a novel analytical instrument. The harmonic distribution, in complex signals caused by cells exposed to harmonic free waveforms and occupying part of the electrode/suspension interface volume, was shown to be almost entirely due to the change in the standing interfacial transfer function by the (dielectrically nonlinear) presence of cells. Thus, the characteristic interfacial non-linearity is viewed as variable, being uniquely modulated by the presence of particular cells in the interfacial region. Little can be attributed to bulk (far field) effects. The tendency for subtle (characteristic) signal distortion to occur as a function of particulate (cell or molecular) occupancy of the near electrode interfacial region under controlled current conditions leads to the method of sample characterisation by harmonic (Fourier) analysis. We report here, as a sequel to our original studies (Hutchings et al., 1993; Hutchings and Blake-Coleman, 1993), preliminary results of the harmonic analysis of microbial suspensions under controlled signal conditions using a three-electrode configuration. These data provide three-dimensional graphical representations producing harmonic 'surfaces' for various microorganisms. Thus, cell type differences are characterised by their 'harmonic signature'. The visual distinction provided by these 'surface' forming three-dimensional plots is striking and gives a convincing impression of the ability to identify and enumerate specific microorganisms by acquisition of cell-modulated electrode interfacial Fourier spectra.
利用一种新型分析仪器，研究了各种微生物在靠近浸入式电极时暴露于周期性（随时间变化）电场中的频率/幅度效应。细胞暴露于无谐波波形并占据电极/悬浮液界面部分体积时所产生的复杂信号中的谐波分布，几乎完全是由于细胞（介电非线性）的存在导致驻波界面传递函数发生变化所致。因此，特征性界面非线性被视为可变的，由界面区域中特定细胞的存在进行独特调制。几乎没有可归因于体（远场）效应的因素。在受控电流条件下，随着近电极界面区域颗粒（细胞或分子）占有率的变化，微妙（特征性）信号失真的趋势导致了通过谐波（傅里叶）分析进行样品表征的方法。作为我们原始研究（哈钦斯等人，1993年；哈钦斯和布莱克 - 科尔曼，1993年）的后续，我们在此报告使用三电极配置在受控信号条件下对微生物悬浮液进行谐波分析的初步结果。这些数据提供了三维图形表示，为各种微生物生成谐波“表面”。因此，细胞类型差异通过其“谐波特征”来表征。这些形成“表面”的三维图所提供的视觉区别非常显著，给人一种通过获取细胞调制电极界面傅里叶光谱来识别和枚举特定微生物的能力的令人信服的印象。
