Biological sensor based on a lateral electric field-excited resonator

Abstract

This paper describes a biological sensor based on a lateral electric field-excited resonator using an X-cut lithium niobate plate. Its potential was shown through the example of biological interaction between bacterial cells and specific bacteriophages. The detection was based on the analysis of the measured real and imaginary parts of electrical impedance for a resonator loaded by the biological suspension under study. It has been shown that the sensor is sensitive to specific interactions between bacterial cells and specific bacteriophages in a pure state as well as in the presence of extraneous microflora. The degree of electrical impedance variation resulting from the biological interaction depends on the numbers of phage particles and bacteria cells. The sensor may be used not only for the qualitative analysis of bacteria but also for their quantitative detection.

The study of piezoelectric lateral-electric-field-excited resonator

“…The second variant involves the application of an absorbing layer to a certain part of the resonator that suppresses spurious oscillations and allows one to form clear resonant frequency dependence for the real and imaginary parts of electrical impedance and admittance [21], [22]. Using this resonator, biological sensors have been developed which enable bacterial cells to be detected directly in liquid phase under their interaction with bacteriophages [25], miniantibodies [26], and antibodies [27]. The influence of the width of a gap between the electrodes and the width of the absorbing layer on the resonant frequency and Q-factor has, however, not been examined in detail.…”

Array of piezoelectric lateral electric field excited resonators

“…Besides, the array of a few acoustically uncoupled resonators placed at one plate makes possible a multisensory biological analyzer if a fluid container is placed at the back side of each resonator [11]. This would allow to simultaneously detect bacterial cells in several samples of suspension under study.…”

Liquid sensor based on a piezoelectric lateral electric field-excited resonator

“…Moreover, it has been shown in Ref. [16] that the frequency dependencies of the real parts of electrical impedance near the resonance may appear to be strongly blurred with the resonator contacting even with nonviscous and nonconducting liquid. So this makes strict determination of resonant frequency difficult.…”

“…Fig. 1 depicts the schematic of a sensor containing the resonator and a liquid container whose analogue has been used in the course of biological experiments [16]. The resonator was a piezoelectric 510 lm thick X-cut lithium niobate plate (lateral dimensions 25 Â 25 mm) with two rectangular electrodes of dimensions 5 Â 10 mm placed on one of its sides.…”