Browsing by Author "Morais, R."
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- Bioimplantable impedance and temperature monitor low power micro-system suitable for estrus detectionPublication . Miranda, N.; Morais, R.; Dias, M.; Viegas, C.; Silva, F.; Serôdio, C.; Almeida, J.; Azevedo, J.; Reis, M.C.Based on cyclic physiologic animal bioimpedance and body temperature a new method is being evaluated to predict estrus in dairy cattle with the aim of improving artificial insemination efficiency. Preceding in-vivo tests are being performed with a dedicated system based on the impedance converter AD5933, and a two-electrode configuration bioimplantable capsule. Acquired results will allow the optimal design of an implantable and autonomous low-power system. The implantable microsystem is being designed and simulated employing low-power techniques in a 0.35μm CMOS standard process.
- Characterization and testing of a shock absorber embedded sensorPublication . Ferreira, C.; Ventura, P.; Grinde, C.; Morais, R.; Valente, A.; Neves, C.; Reis, M.This article presents the characterization of a shock absorber embedded sensor (SAES) for real-time monitoring of the condition of vehicle shock absorbers in everyday use. A prototype system was built using a custom designed monolithic silicon combined accelerometer, pressure and temperature sensors. The characterization of the SAES was performed and the obtained results meet and even outperform the specification requirements. The SAES was installed in a shock absorber, with adjustable damping properties, and submitted to road tests. Results show that the condition of a shock absorber can be effectively assessed with the presented SAES. Ensuring that shock absorbers are replaced before reach unacceptable condition, this system will increase onboard comfort and vehicle safety.
- A novel monolithic silicon sensor for measuring acceleration, pressure and temperature on a shock absorberPublication . Ferreira, C.; Ventura, P.; Grinde, C.; Morais, R.; Valente, A.; Neves, C.; Reis, M.J.C.S.; Henriques Ferreira, Carlos Daniel; Neves, CarlosA fabricated micro-mechanical sensor to assess the condition of automotive shock absorbers is presented. The monolithic sensor, measures the oil temperature, acceleration and internal pressure of the shock absorber. A dual mass accelerometer with optimized beam geometry is used for acceleration readout. In addition, a 23.1 μm thickness square membrane and two buried resistors are used for pressure and temperature sensing respectively. The proposed miniaturized sensor can be effectively integrated with standard single- and dual-tube shock absorbers. The data acquired during normal vehicle operation can be continuously used to monitor the condition of the shock absorbers, allowing shock absorbers to be replaced before their degradation significantly reduce the comfort, performance and safety of the vehicle.
- Optimized Design of a Piezoresistive Pressure Sensor with Measurement Span of 1MPaPublication . Ferreira, Carlos; Grinde, C.; Morais, R.; Valente, A.; Neves, C.; Reis, M.This paper presents a piezoresistive pressure sensor with a measurement span of 1MPa and capable to withstand peak pressures around 10MPa. The sensor design, based on a square membrane, was optimized for enhanced sensitivity, high linearity and low sensitivity variations between fabricated samples. Being the asymmetry of the mechanical stress peaks, the ratio between the membrane area and its thickness, and the tolerances of the bulk micromachining process considered for the optimal positioning of the piezoresistive sensing elements. Practical results show a mean sensitivity of 30.9mV/V/MPa with a standard deviation of 0.65mV/V/MPa and a linearity error of 0.15% of the scale span.