Signal conditioning circuit for gel strain sensors

Conductive Hydrogels are soft materials which have been used by some researchers as resistive strain sensors in the last years. The electrical resistance change, when the sensor is stretched or compressed, is usually measured by the two-electrode method. This method is not always suitable to measure the electrical resistance of polymers-based materials, like hydrogels, because it could be highly influenced by the electrode/sample interface, as explained in this study. For this reason, a signal conditioning circuit, based on four-electrode impedance measurements, is proposed to measure the electrical resistance change when the gel is stretched or compressed. Experimental results show that the tested gels can be used as resistance force/pressure sensors with a quite linear behaviour.

Development of Biomedical Dynamometer for Measurement of Grip Strength in Mice Modeled with Cerebral Palsy

This research aimed to develop a biomedical dynamometer capable of measuring the grip strength of the forepaws of laboratory mices to verify the posterior phase, the effect of modeled cerebral palsy in the animal. The equipment was developed using a stainless steel blade, two double strain gages, a signal conditioning circuit that was connected to a software for acquisition, processing and plotting of graphs and tables in Excel. The metal blade has a length of 18.5 cm, a width of 1.5 cm and a thickness of 2 mm and a double strain gage model pa-09-125ha-350-l8 from Excel Sensors (Brazil), was glued to each face. The two double strain gages were connected in a Wheatstone bridge, which produces an analog response due to mechanical deformation of the blade, with force applied by the mice. This response was submitted to a signal conditioning circuit developed with Arduino that modulated the input wave, generated 10000 times amplification and performed filtering 4th order using Butterworth filter. Finally, a software developed in Labview 2019 of National Instruments (USA) was used for acquisition, processing and plotting of graphs and tables in Excel of the measurements performed. In the next step, the dynamometer was calibrated for sequential loading of masses of 0, 15.48 g, 31.53 g, 46.88 g to 62.47 g and also for sequential unloading of the same masses. For this, the masses were hung on a nylon string that was attached to the free end of the metal sheet. The final test was to measure the response time of the dynamometer with a stopwatch, when hanging a mass of 62.47 g on the nylon thread that was cut abruptly with scissors. Some of the main results of the calibration were as follows: 15.48 g generated 3.70 V, 31.53 g generated 7.48 V and 62.47 g gene rated 14.80 V and the response time was 0.3 s. These answers show that the dynamometer can be used to measure the grip strength of mice and can be modified for use in humans.

A Novel Rail-to-Rail Input Swing Threshold-Inverter Multi-Bit Quantizer Using Interpolation Technique for Sampled-Data Circuits

In this paper, a novel and simple multi-bit quantizer based on the threshold inverter quantization (TIQ) approach is presented for use in sampled-data circuits. The key part is a front-end signal conditioning circuit with the aid of the interpolation technique that makes it possible to realize a rail-to-rail input range operation over the conventional threshold inverter-based quantizer circuits while maintaining the benefits of the TIQ structure without employing any analog-intensive circuits such as current sources or amplifiers, thus achieving a digital-compatible implementation. Simulation results in TSMC 90-nm CMOS technology at a power-supply voltage of 1[Formula: see text]V confirm the efficient performance of the proposed circuit.

Purwarupa Spirometer Digital Berbasis LABVIEW

Spirometer is an instrument used to measure the vital capacity of the human lung and is usually only found in large hospitals or clinical laboratories because of its relatively high price. However, to find out how this instrument works, a prototype of the spirometer is made by utilizing a Labview-based interface. This prototype was developed by making an air channel or funnel the size of a human mouth which then the air will be detected by a pressure sensor connected to a signal conditioning circuit and then the measurement information data is forwarded by the Arduino to a computer to be processed into digital data which is then converted into vital capacity information data. lungs. The results obtained from this research are that it can make a spirometer prototype according to its function which is hoped to be used as a learning medium in the field of medical instrumentation by measuring the vital capacity of the lungs in the form of height, age, and gender of a person, besides that the results are in the form of a graphic display. and numerical data from the measurement process on the GUI display in LabVIEW. This prototype was calibrated using a syringe with a volume of 2 liters and the accuracy rate was 99.63% with a standard deviation value of ± 70.61 ml and a precision value of 1.76% from these results.

Performance Analysis, Modelling, and Development of a Signal Conditioning Unit of N-Type Metal Oxide Gas Sensor for Acetone Gas Detection.

Metal oxide semiconductors have been widely used in the eld of gas sensor study. Various researches are being done to improve the sensitivity of the sensing material for applications like breath analyzers. In this work, a theoretical investigation and analysis of the n- type metal oxide for Acetone gas detection are carried out. The rate of change of resistance of the sensing material with respect to the change in the concentration of the target gas is analyzed. Acetone being a reducing gas the resistance was found to decrease for n-type material. The simulations were done using COMSOL Multiphysics and results showed that the resistance of the sensing layer varies with the concentration of the target gas. Also, the performance analysis of sensors has been compared with the experimental results. Further, we have also derived a mathematical expression connecting the relationship between the concentration of gas and the rate of change of resistance. The resistance change is observed to be proportional to the target gas concentration. A signal conditioning circuit was also designed for providing a user-friendly interface for monitoring the gas concentration. The simulation of the signal conditioning circuit was done using Proteus Design Suite. This work will aid researchers to define and predict the behaviour of gas sensors.

Design Of Asthma Detection Devices Through Heart Rate and Oxygen Saturation

Respiratory problems can cause asthma, acute asthma attacks are very difficult to predict because they often occur suddenly and asthma can also cause death in sufferers because the breath can suddenly stop. The purpose of this research is to design an asthma detection device through indicators of heart rate and oxygen saturation. The contribution of this study is to categorize the patient's condition by looking at the value of the heartbeat and oxygen saturation so that when asthma occurs the message of a location will be sent. To measure heart rate and oxygen saturation, a Nellcor finger sensor is placed on the patient's index finger. The finger sensor enters the signal conditioning circuit, then sent to the microcontroller to be processed to produce a heart rate value and the percentage of oxygen saturation. The testing of this tool is done by comparing the module with a standard measuring instrument that produces the highest value of oxygen saturation error which is 1.715% and the largest value of heart rate error is 3.548%. The results showed that the device was appropriate to use, because in the Medical Devices Testing and Calibration Guidelines of the Ministry of Health of the Republic of Indonesia in 2001, the maximum limit in oxygen saturation error tolerance was 2%, and heart rate was 5%. The results of this study can be implemented in patients who have been diagnosed with asthma so that it can facilitate the family in monitoring the patient's condition.