Analog isolated electronic dynamometer based on a magnetoresistive current sensor.

In this work, an electronic system is presented to measure the force applied by a solenoid. The originality of the work is focused on the use of a magnetoresistive current sensor to provide the isolation barrier needed in the actual industrial plant where the solenoids are working. The design of the electronic system is presented as well as experimental measurements as a result of a calibration process showing a negligible hysteresis with that specific sensor. The magnetoresistive current sensor is used to develop transmission functions rather than playing its usual sensing roles.

Note: A non-invasive electronic measurement technique to measure the embedded four resistive elements in a Wheatstone bridge sensor.

The work shows a measurement technique to obtain the correct value of the four elements in a resistive Wheatstone bridge without the need to separate the physical connections existing between them. Two electronic solutions are presented, based on a source-and-measure unit and using discrete electronic components. The proposed technique brings the possibility to know the mismatching or the tolerance between the bridge resistive elements and then to pass or reject it in terms of its related common-mode rejection. Experimental results were taken in various Wheatstone resistive bridges (discrete and magnetoresistive integrated bridges) validating the proposed measurement technique specially when the bridge is micro-fabricated and there is no physical way to separate one resistive element from the others.

Note: Direct sensor resistance-to-frequency conversion with generalized impedance converter.

In this note a squared output signal is generated from an astable circuit. Its frequency has a linear dependence on the resistance value of a resistive temperature sensor. The main circuit to obtain this direct relationship is the generalized impedance converter configured as a capacitor controlled by a sensor resistance. The proposed measurement method allows a direct analog-to-digital interface of information involved in resistive sensors. The converter finds applications in portable low voltage and low power design of instrumentation electronic systems.

[Sensitivity of the anal canal: study techniques and results in normal subjects]. / Sensibilidad del canal anal. Técnicas de estudio y resultados en sujetos normales.

AIM: To describe a technique for the study of the anal canal sensitivity to electric and thermal stimulation, and to investigate it prospectively in normal subjects. EXPERIMENTAL DESIGN: Mucosal electrosensitivity and thermal sensation of the anal canal is correlated with motor parameters: perineometry, manometry and electrophysiology. PATIENTS: 41 control subjects (20M & 21F) with normal anorectal anatomophysiology. RESULTS: In the middle anal canal minimum electrosensibility thresholds were present, and they were similar to the thermal profile. A significant impairment in electrosensitivity was observed as a function of age, but no differences between the sexes were found. Lower thresholds were obtained than cold temperatures (p < 0.001). Both tests of sensitivity correlated with pudendal motor parameters. The maximal thermal difference in the anal canal was 0.28 degree C, while the minimal detectable temperature change was 0.46 +/- 0.1 degrees C. CONCLUSIONS: The sensitivity of the anal canal is greatest in the zone of the anal valves and better in response to hot than cold stimulus. As the minimum detectable temperature change has been greater than the difference of temperature between the low and high anal canal, we suggest that discrimination is not possible on the basis of thermal differences.