Mobile Acoustic Wave Platform Deployment in the Amazon River: Impact of the Water Sample on the Love Wave Sensor Response

Elaboration and Characterization of a New Heavy Metal Sensor Functionalized by Extracellular Polymeric Substances Isolated from a Tunisian Thermophilic Microalga Strain Graesiella sp

The present study aimed to develop and characterize new heavy metal sensors functionalized by extracellular polymeric substances (EPSs) isolated from a Tunisian thermophilic microalga strain Graesiella sp. The elaborated sensor showed a highly homogeneous character and revealed a microstructural lamellar arrangement, high crystalline nature, and several functional groups. Electrochemical impedance spectroscopy (EIS) and acoustic wave sensing were used as sensing techniques to explore the ability of microalgae-EPS-functionalized sensors to detect cadmium and mercury as heavy metals. For impedimetric measurements, a two-dipole circuit was adopted and showed good-fitted results with a low total error. The acoustic sensor platforms showed good compatibility with EPS in adjacent water. For both EPS-functionalized sensors, metal ions (Cd²⁺, Hg²⁺) were successfully detected in the concentration range from 10^-10 M to 10^-4 M. Impedimetric sensor was more sensitive to Cd²⁺ at low concentrations before saturation at 10^-7 M, while the acoustic sensor exhibited more sensitivity to Hg²⁺ over the full range. The results highlight a new potential alternative to use microalgae EPSs as a sensitive coating material for the detection of heavy metals. However, its use in a real liquid medium requires further investigation of its selectivity in the presence of other compounds.

A Study of Optimizing Lamb Wave Acoustic Mass Sensors' Performance through Adjustment of the Transduction Electrode Metallization Ratio

This paper presents the design and simulation of a mass sensitive Lamb wave microsensor with CMOS technology provided by SilTerra. In this work, the effects of the metalization ratio variation on the transmission gain, total harmonic distortion (THD), and two different resonant modes (around 66 MHz and 86 MHz) are shown. It has been found that the metalization ratio can be adjusted in order to obtain a compromise between transmission gain and sensitivity, depending on the design criteria. By adding a Si3N4 layer on top of the device, a five-fold improvement in transmission gain is reached. It was also shown that the transmission of the input differential IDT configuration is 20% more efficient than a single terminal. With this combination, the mass sensitivity is about 114 [cm2/gr].

A Novel Impedimetric Sensor Based on Cyanobacterial Extracellular Polymeric Substances for Microplastics Detection

Cyanobacterial extracellular polymeric substances "EPS" have attracted intensive concern in biomedicine and food. Nevertheless, the use of those polymers as a sensor coating material has not yet been investigated mainly for microplastic detection. This study focuses on the application of EPS as a sensitive membrane deposited on a gold electrode and investigated with electrochemical impedance spectroscopy to detect four types of microplastics with a size range of 0.1 µm to 1 mm. The surface properties of this impedimetric sensor were investigated by Scanning electron microscopy, Fourier transforms infrared spectroscopy, and X-ray spectroscopy and, showed a high homogenous structure with the presence of several functional groups. The measurements showed a high homogenous structure with the presence of several functional groups. The EPS-based sensor could detect the four tested microplastics with a low limit of detection of 10^-11 M. It is the first report focusing on EPS extracted from cyanobacteria that could be a new quantification method for low concentrations of microplastics.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10924-022-02555-6.