Impedance Spectroscopy (IS) has been shown to be a non-invasive and reliable technique for the electrical characterization of biological materials. This paper presents the design and implementation of reliable, reusable wells that are used to perform IS measurements of aqueous solutions. These reusable wells are detachable, easy to clean and low-cost and they are made up of a platen on a Printed Circuit Board (PCB) and the chambers are manufactured using 3D-printing technology. In this case, in order to verify its functionality, IS measurements of electrolytic and non-electrolytic aqueous solutions were carried out. Initially, as a reference, the impedance spectrum of a Hanks’ solution was obtained following a proposed measurement protocol. Then, we analyse this spectrum and we propose an Equivalent Electrical Model (EEM) for validating the reusable wells. Finally, IS measurements are carried out on aqueous solutions of molecular D-glucose and sodium chloride prepared in Hanks’ solution and deionized water, by considering physiological concentrations. The parameter values of the EEMs of each solution tested were obtained using genetic algorithms and Matlab and, from these values, it is possible to conclude that the measurements performed are unable to differentiate the physiological concentration of glucose in the aqueous solution used. Also, from these results, it can be concluded that the designed wells are suitable for IS measurements of aqueous solutions and that they can be used in Electrical Cell Impedance Sensing (ECIS) or applications that require electrical characterization of solutions.
Today several electronic applications are demanding linear ICs that operate on a single supply rail, with the same performance of dual supply parts. Power consumption is now the key parameter for those battery operated systems and in some instances, more important than cost. In fact, through the effort of the manufacturers, doing more with less, is possible to find notable performance OpAmp's; parameters such as the offset voltage, leakage current and the precision of the gain are increasingly improved. In addition, in applications where the low-signal processing is required, as in many of the applications above described; in some cases the use of reconfigurable circuits is necessary to improve and highlight the performance of these OpAmp's. Then, the performance of a stage can be improve on the fly. This paper presents a design approach for amplification and active filter stages, with auto adjustable features, for signal processing greater than 100 mV and up to 1 KHz. The proposed approach uses a successive approximation algorithm for setting gain stages, and algorithms based on Wavelets-Mallat discrete thresholding and power spectral density of the signal for tuning the active filters. Its implementation based on a reconfigurable mixed-signal circuit, PSoC1, is also presented and validated. The results show that the proposed helps to improve the dynamic range and SNR of a signal, without the need to redesign and implementation processes of these stages, very commons in lowsignal processing. These implementation can be used in applications where signals with the above conditions, need to be conditioned. For example: biomedical and semiconductor sensor signals.
Today, the environmental monitoring and quality have a growing interest. This promotes the development of new monitoring tools, and especially those with outstanding reliability and response time, and nonstationary features. This paper presents the design and implementation of a transportable gas detection and environmental monitoring device. Ideas taken from the Arduino and Lego constructions are kept in mind during the design of the device, looking further facilitate the development of product family of this device; likewise, the use of reconfigurable and interconnectable platforms with open hardware are considered. The transducers have been selected based on their reliability, small size and easy inclusion in an electronic system. Then, was developed a device that supports transducers for environmental gases, such as: carbon monoxide (CO), ozone (O 3 ), volatile organic compounds (VOC), nitrogen dioxide (NO 2 ) and sulfur dioxide (SO 2 ); as well as the possibility to interface with other systems for common gases such as carbon dioxide (CO 2 ) and oxygen (O 2 ) before developed. Other environmental measures such as speed and wind direction, temperature and relative humidity, may also be included. In this case, a configurable platform based on mixed-signal circuits, PSoC5, was used for the development of embedded system. This platform can be interfaced with different Arduino shields and achieves the integration of several analog functions. This system manages, acquires and processes signals from the above transducers. The measurements can be displayed on an LCD display, save into an SD memory and send to the Web using Ethernet interface. The device is hand size, easy to carry and can operate with a battery. Its user interface is simple and provides updated and in-situ readings. Currently, successful results have been obtained from the functional and metrology testing of the manufactured prototype.
Fruits and vegetables in the daily diet offer protective action against free radicals, inflammatory agents, and fungi. Polyphenols, found in these natural products, have been studied in order to understand their contribution to the prevention of multiple diseases. The identification and quantification of polyphenols have been evaluated uding the Folin-Ciocalteu method. This procedure requires several chemical reagents and different electrical devices, generating chemical waste and at great expense. There is a need to develop polyphenol identification and quantification techniques that are less costly and generate minimum contamination. Electrical bioimpedance spectroscopy (EBS) is a promising alternative that could contribute to measuring total polyphenol content in fresh fruits and vegetables. This study focused on using EBS and characterizing electrical response in fruit pulp from three different Colombian passifloras. The study aimed to compare the electrical parameter values of an Equivalent Electrical Model (EEM) to the total polyphenol content quantified by the Folin-Ciocalteu method.
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