Electrical imaging of plant root zone: A review

The invention discloses a multi-frequency electrical impedance imaging device based on an FPGA. The device includes an FPGA processor, a DA conversion circuit, a differential current single-ended voltage circuit, a voltage magnitude regulation circuit, a voltage controlled current source circuit, a multi-way switch, a physical model, a pre-posed high-pass filter circuit, a differential amplification circuit, a variable gain amplification circuit, a program-controlled filter circuit, a phase sensitive demodulation circuit, an AD conversion circuit and a PC machine; the FPGA processor generates a sine-cosine digital signal, the signal is converted into a constant flow source and serves as excitation current, and the excitation current is input into a physical model when an excitation current channel is selected through the multi-way switch; the FPGA processor inputs the collected voltage signal generated by the physical model into the pre-posed high-pass filter circuit for filtering, then the signal is subjected to secondary amplification, program-controlled filtering and phase sensitive demodulation in sequence, and the PC machine obtains an electrical impedance imaging figure of a to-be-measured object according to the digital signal. The device overcomes the parameter error, can effectively filter the collected voltage signal and has good accuracy.

Multi-frequency electrical impedance imaging device based on FPGA

Evaluation of electrical impedance tomography sensor using internal-external electrodes for small-scale cylindrical root zones

Introduction: The following article shows a systematic review of publications on hardware topologies used to capture and process electrical signals used in Electrical Impedance Tomography (EIT) in medical applications, as well topicality of the EIT in the field of biomedicine. This work is the product of the research project “Electrical impedance tomography based on mixed signal devices”, which took place at the University of Cauca during the period 2017-2019. Objective: This review describes the operation, topicality and clinical use of Electrical Impedance Tomography systems. Methodology: A systematic review was carried out in the IEEE-Xplore, ScienceDirect and Scopus databases. After the classification, 106 relevant articles were obtained on scientific studies of EIT systems; applications dedicated to the analysis of medical images. Conclusions: Impedance-based methods have a variety of medical applications as they allow for the reconstruction of a body region, by estimating the conductivity distribution inside the human body; this is without exposing the patient to the damaging effects of radiation and contrast elements. Impedance-based methods are therefore a very useful and versatile tool in the treatment of diseases such as: monitoring blood pressure, detection of atherosclerosis, localization of intracranial hemorrhages, determining bone density, among others. Originality: It describes the necessary components to design an EIT system, as well as the design characteristics depending on the pathology to be visualized. Restrictions: The review focuses on aspects of the performance of an EIT system, depending on the pathology analyzed. Considering the hardware advances, it is possible to increase the acquisition speed (temporal resolution), thus improving the spatial resolution and the quality of the reconstructed image.

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Electrical Impedance Tomography: Hardware Fundamentals And Medical Applications

Multi-frequency complex conductivity sparse imaging of plant root zone based on space-frequency correlation

The hardware design of tuber electrical resistance tomography (TERT) system is one of the key research problems of TERT data acquisition system. The TERT system can be applied to the tuber growth process monitoring in agriculture, i.e., the TERT data acquisition system can realize the real imaging of tuber plants in soil. In TERT system, the imaging tuber and soil multiphase medium is quite complexity. So, the impedance test and analysis of soil multiphase medium is very important to the design of sensitive array sensor subsystem and signals processing circuits. In the paper, the soil impedance test experimental is described and the results are analysed. The data acquisition hardware system is designed based on the result of soil medium impedance test and analysis. In the hardware design, the switch control chip ADG508, the instrumentation amplifier AD620 and programmable amplifier AD526 are employed. In the meantime, the phase locked loop technique for signal demodulation is introduced. The initial data collection is given and discussed under the conditions of existing plant tuber and no existing plant tuber. Conclusions of the hardware design of TERT system are presented.

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Hardware Design of Tuber Electrical Resistance Tomography System Based on the Soil Impedance Test and Analysis

The application of electrical resistance tomography (ERT) technology has been expanded to the field of agriculture, and the concept of TERT (Tuber Electrical Resistance Tomography) is proposed. On the basis of the research on the forward and the inverse problems of the TERT system, a hybrid algorithm based on genetic algorithm is proposed, which can be used in TERT system to monitor the growth status of the plant tubers. The image reconstruction of TERT system is different from the conventional ERT system for two phase-flow measurement. Imaging of TERT needs more precision measurement and the conventional ERT cares more about the image reconstruction speed. A variety of algorithms are analyzed and optimized for the purpose of making them suitable for TERT system. For example: linear back projection, modified Newton-Raphson and genetic algorithm. Experimental results showed that the novel hybrid algorithm is superior to other algorithm and it can effectively improve the image reconstruction quality.

/pdf/research-on-image-reconstruction-algorithms-for-tuber-1tq1vc7ckf.pdf

Research on Image Reconstruction Algorithms for Tuber Electrical Resistance Tomography System

The present invention relates to a tuber resistance imaging data acquisition system based on FPGA. An FPGA chip is used for controlling hardware circuit and chips, and conducts sweeping control on excitation and signal acquisition of 6 layers of planar array electrode in a TERT system, in order to achieve data acquisition of TERT system. The tuber resistance imaging data acquisition system based on FPGA uses the FPGA chip scheme for data collection; because of its strong flexibility, the FPGA can be programmed by HDL language to achieve different functions. The developed product has excellent characteristics good performance and motile peripheral scalable I/Os, and can achieve high-speed acquisition of a large amount of data, so that the data acquisition system can well meet the requirements of TERT system for data acquisition.

Tuber resistance imaging data acquisition system based on FPGA

This article clarifies a high-sensitivity mass sensing mechanism, intrinsically correlated with energy relocalization. A sensing theory is derived to predict the amplitude–frequency curve with respect to the effect of mass perturbation, where high linearity is observed for both amplitude changes and frequency shifts. A localization factor is defined to characterize the degree of the energy localization, and its physical rationality is demonstrated with a coupled three-beam array as an example. A higher detection sensitivity via energy relocalization, increased by about 123.8% based on the amplitude change and by 250% based on the localization factor, is experimentally obtained with a high vibration amplitude compared to a low one. A mass sensing-warning scheme is further proposed for low-concentration monitoring and high-concentration warning, applicable to the detection and warning of a gas leak, dust pollution, harmful chemicals, and so on.

Highly Sensitive Mass Sensing Scheme via Energy Relocalization With a Coupled Three-Beam Array

In our previous related works of DTIP, amplitude enhancement was studied back in DTIP2011, while damping issue was preliminarily considered in DTIP2017. In DTIP2018, vibration characteristics was analyzed in a four cantilever array with and without mass perturbation. In this paper however, a calibration methodology is proposed for coupled resonators with manufacturing errors, where the detuning of their stiffness and mass will destroy the perfect localized equilibrium state. A localized trio cantilever array is taken as an example. The basic idea is to calibrate the manufacturing error on corresponding cantilever by sweeping the frequency before and after adding a known mass. The proposed methodology is supported at both theoretical and simulation levels for calibrating the manufacturing errors in the length, width, and thickness directions of the entire structure respectively.

Shuyi Liu

Papers

Hardware Design of Tuber Electrical Resistance Tomography System Based on the Soil Impedance Test and Analysis

Research on Image Reconstruction Algorithms for Tuber Electrical Resistance Tomography System

Tuber resistance imaging data acquisition system based on FPGA

Highly Sensitive Mass Sensing Scheme via Energy Relocalization With a Coupled Three-Beam Array

Localization in Coupled Systems: Part IV – Geometric Manufacturing Errors in A Mode-localized Three Cantilever Array