Luís Alexandre Rocha

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— This paper presents LPRT, a new medium access control (MAC) protocol for wireless sensing and actuation systems. Some of the characteristics of the proposed protocol are low power consumption, support for real-time and loss intolerant traffic through contention-free operation and a retransmission scheme, flexibility, and high throughput efficiency. The(More)
A test technique for capacitive MEMS accelerometers and electrostatic microactuators, based on the measurement of pull-in voltages and resonance frequency, is described. Using this combination of measurements, one can estimate process-induced variations in the device layout dimensions as well as deviations from nominal value in material properties, which(More)
The IEEE 802.15.4 Medium Access Control (MAC) protocol is an enabling standard for wireless sensor networks. In order to support applications requiring dedicated bandwidth or bounded delay, it provides a reservation-based scheme named Guaranteed Time Slot (GTS). However, the GTS scheme presents some drawbacks, such as inefficient bandwidth utilization and(More)
—The pull-in voltage of a single-side anchored free-standing beam, under lateral deflection, has been investigated for application as a dc voltage reference. Two sets of electrodes, alongside the tip, are used for parallel-plate type of electrostatic actu-ation of the 200 m long beam in the plane of the wafer. Another set of buried electrodes is aligned(More)
—The reproducibility over temperature and time of the pull-in voltage of micromechanical structures has been analyzed and verified using fabricated devices in silicon. The pull-in structures are intended for use as an on-chip voltage reference. Microbeams of 100-m length, 3-m width, and 11-m thickness are electrostatically actuated with a very reproducible(More)
The constant growth of the elderly population in the world creates new challenges and opportunities in health care systems. New technological solutions have to be found in order to meet the needs and demands of our aging society. The welfare and quality of life of the elderly population must be a priority. Continuous physical activity will play an important(More)
BACKGROUND The cause of frequent falls in patients with Alzheimer's disease (AD) is still not well understood. Nevertheless, balance control and sensory organization are known to be critical for moving safely and adapting to the environment. METHODS We evaluated postural stability in 20 AD patients (11 fallers and 9 nonfallers) and 16 healthy controls(More)
Inertial measurement Units (IMU) (accelerometers and gyroscopes), placed in strategic parts of the human body, are a growing field on kinetic posture and imbalance study in Alzheimer's Disease (AD). On the other hand, Artificial Neural Network (ANN) are a powerful statistical tool used on pattern recognition on big data such as IMU kinetic records. Still,(More)
Postural control is a complex dynamic mechanism, which integrates information from visual, vestibular and somatosensory systems. Idiopathic Parkinson's disease (IPD) patients are unable to produce appropriate reflexive responses to changing environmental conditions. Still, it is controversial what is due to voluntary or involuntary postural control, even(More)