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.

Modeling and Analysis of the Power Conditioning Circuit for an Electromagnetic Human Walking-Induced Energy Harvester

Among the various alternative energy sources, harvesting energy from the movement of the human body has emerged as a promising technology. The interaction between the energy harvesting structure and the power conditioning circuit is nonlinear in nature, which makes selecting the appropriate design parameters a complex task. In this work, we present an electromagnetic energy harvesting system suitable for recovering energy from the movement of the lower limb joints during walking. The system under study is modeled and simulated, considering three different scenarios in which the energy source is the hip, knee, and ankle joint. The power generated by the energy harvester is estimated from kinematic data collected from an experimental gait study on a selected participant. State-space representation and Recurrence plots (RPs) are used to study the dynamical system’s behavior resulting from the interaction between the electromagnetic structure and the power conditioning circuit. The maximum power obtained through the simulation considering a constant walking speed of 4.5 km/h lays in the range of 1.4 mW (ankle joint) to 90 mW (knee joint) without implementing a multiplier gear.

Implantable Blood Pressure Sensors with Analogic Thermal Drift Compensation

Implantable pressure sensors represent an important part of the research activity in laboratories. Unfortunately, their use is limited by cost, autonomy and temperature-related drifts. The cost of use depends on several parameters, particularly their low battery life and the need for miniaturization to be able to implant the animals and monitor them over a time that is long enough to be physiologically relevant. This paper studied the possibility of reducing the thermal drift of implantable sensors. To quantify and compensate for the thermal drift, we developed the equivalent model of the piezoresistive probe by using the Cadence software. Our model takes into account the temperature (34–39 °C) as well as the pressure (0–300 mmHg). We were thus able to identify the source of the drift and thanks to our model, we were able to compensate for it thanks to the compensation circuits added to the conditioning circuits of the sensor. The maximum relative drift of the sensor is (0.1 mV/°C)/3.6 mV (2.7%), a drift of the conditioning circuit is (0.98 mV/°C)/916 mV (0.1%) and the whole is (13.4 mV/°C)/420 mV (32%). The compensated sensor shows a relative maximum drift of (0.371 mV/°C)/405 mV (0.09%). The output voltage remains stable over the measurement temperature range.

The Effects of Exercise During a 10-Week Basic Military Training Program on the Physical Fitness and the Body Composition of the Greek Naval Cadets

ABSTRACT Introduction The period of basic military training (BMT) is a sudden change in the individual habits of the trainees and is characterized by significant improvements in body composition such as the percentage of body fat (%BF) and lean body mass (BM). Research has shown that physical activity during the period of BMT lasting 7–10 weeks has positive effects on the physical condition and BM of cadets. The purpose of this study was to examine the effects of training combining cardiovascular conditioning, circuit strength training, swimming, team sports, and obstacle course on physical fitness and body composition during a 10-week BMT period over 4 years in the Hellenic Naval Academy (HNA). Materials and Methods The sample consisted of 185 Greek cadets of the HNA (age: 18.4 ± 0.7 years, height: 1.77 ± 6.7 m, BM: 72.6 ± 9.1 kg), of which 153 was male (age: 18.3 ± 0.6 years, height: 1.79 ± 5.8 cm, BM: 75.3 ± 7.6 kg) and 32 was female (age: 18.6 ± 0.9 years, height: 1.68 ± 2.8 cm, BM: 59.9 ± 3.1 kg). The cadets participated each year for 4 years in the BMT, performing 94 training sessions, five times a week. The weekly training program included cardiovascular conditioning, circuit strength training, swimming, team sports, and obstacle course. The measurements of the participants before and after BMT were on BM, %BF, and body mass index (BMI); on the number of sit-ups (SU1), push-ups (PU1), and pull-ups (PullU1) in 1 minute; and on the 12-minute aerobic Cooper test (12-min run). Results The results of the study showed that the BM of the cadets decreased significantly by 2.5%, (t184 = 17.591, P < .01), in men by 2.7% (t152 = 16.243, P < .01) and in women by 2.2% (t31 = 9.280, P < .01). Body mass index (BMI) decreased significantly by 2.6% (t184 = 17.681, P < .01), in men by 3.0% (t152 = 16.046, P < .01) and in women by 2.3% (t31 = 9.224, P < 0.01). Reduction in %BF in all cadets reached 11.3% (t184 = 8.134, P < .01), for men −14.8% (t152 = 8.918, P < .01) and women −2.1% (t31 = 0.860, P > .05) without significant differences between the measurements. The number of push-ups in 1 minute (PU1) significantly increased by 27.6% (t184 = −27.813, P < .01), in women by +35.6% (t31 = 13,864, P < .01). The number of sit-ups in 1 minute (SU1) significantly increased by 27.3% (t184 = −30.501, P < .01), for men +28.8% (t152 = −29.862, P < .01). The number of pull-ups in 1 minute (PullU1) reached 20.8% (t184 = −13.426, P < .01) in total, at similar levels in men (t152 = −13.918, p < .01) and women (t31 = −2.820, P < .01). On the 12-min run, the significant improvement exceeded 10.8% (t184 = −45.289, P < .01), in men by 11.1% (t152 = −45.222, P < .01) while in women by 9.0% (t31 = 15.709, P < .01). Conclusions The results of this study showed that 10 weeks of BMT, which combined cardiovascular conditioning, circuit strength training, swimming, team sports, and obstacle course improved the body composition, cardiorespiratory endurance, and the strength of the Greek HNA cadets.

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.

Experimental Measurements of a Low Power CMOS Analog MPPT Power Conditioning Circuit for Energy Harvesting Applications

This paper presents the complete measured performance and characterization of a fabricated power conditioning integrated circuit for energy harvesters with on-chip maximum power point tracking (MPPT) and external energy storage. This ultra-low power circuit employs an AC/DC-to-DC converter compatible with both AC and DC voltage energy harvesters. The MPPT design follows the perturbation and observation algorithm. This MPPT is capable of tracking the maximum power point of types of energy harvesters. The circuit is implemented using the AMS CMOS 0:35 μm high voltage technology and all the circuit blocks use analog electronic techniques, with the transistors operating in the sub-threshold region, in order to obtain a minimum power consumption. This power conditioning circuit consumes less than 2 μW while featuring an input voltage range of -0:5V to -50V and a power range from 10 μW to 200mW.

Conditioning Optimal Structure Electronics for Piezo-devices

In this paper, an optimal condition- ing electronics conguration is derived for piezo- electric energy harvesting. Unlike conventional studies where optimal energy(power) is extracted from a given piezo-conditioning circuit, this re- search focuses on the determination of the supre- mum: the optimal conguration extracting the biggest possible amount of energy (power) to the load. Along with the electronic design guided by the optimal solution (Pontryaing's principle), LT- Spice simulations are compared side by side with a pre-specied conguration using an LDO pub- lished previously by the authors.