This paper proposes an energy harvesting system for wireless, wearable, and low power health care applications. It discusses the design of a bracelet-like device that converts the difference of temperature between the human body and ambient surrounding using a thermoelectric generator (TEG). The temperature difference causes a small potential difference; an ultra-low voltage is supplied to a step-up converter and power manager. This efficient output is managed, stored, and used to supply low power sensors. The readings of the sensor are transmitted to a multi-platform smart phone application for constant checkup. The system is controlled efficiently to adapt to the changes of external conditions and to overcome the voltage and power variations generated by the TEG. The system relies on green energy which is the best choice for serving as a lifetime power supply for low power wearable medical applications in the foreseeable future.

This paper presents a low power Wireless Safety Detection Sensor (WSDS) system to prevent fatal accidents with vehicles on construction sites. It helps providing increased safety for construction workers and eliminates back over accidents. The system employs three combined techniques which are the (1) 868 MHz radio frequency, (2) directional antennas, and (3) 40 kHz ultrasound waves. In order to secure the area behind the vehicle's rear, a sensing unit that ensures good coverage along with a wearable device for construction workers have been designed. The wearable device consists of a radio transceiver, RF wake up sensor, and an alarm actuator while the sensing unit consists of a processor, radio transceivers, directional antennas, and three ultrasound-based distance sensors. When the WSDS system detects a construction worker in a potential of a hazard, it sends the identification information to a visual display unit located in the driver's cab. At the same time, an alarm in the worker's wearable device is activated. To reserve the battery power of the wearable device, an RF wake up sensor is designed. The RF module will gain a new feature to be a hybrid (active/passive) device with a current consumption as low as 0.5 μÅ at 3 V supply.

This paper proposes a novel integrated micro-viscometer for engine-oil monitoring. The final solution consists of a capacitive micromachined ultrasonic transducer (CMUT) and an application-specific integrated circuit (ASIC). The CMUT is used to generate and capture acoustic waves while immersed in engine oil. The low power transceiver ASIC is interfaced with the CMUT structure for actuation and reception. An integrated charge pump boosts the supply voltage from 3.3 to 22 V to generate the DC polarization voltage of the CMUT. The receiver has a power consumption of 72 µW with an input-referred noise current of 3.2$\frac{pA}{\sqrt{Hz}}$ and a bandwidth of 7 MHz. The CMUT array occupies an area of 3.5 × 1 mm, whereas the ASIC has a chip area of 1 × 1 mm. The system was tested using engine oils of different types and ages at different temperatures. Measurement results show a significant frequency shift due to the dynamic viscosity change that occurs as oil ages. A shift of −1.9 kHz/cP was measured, which corresponds to a shift of 33 Hz/mile. This work paves the way for high accuracy-integrated solutions for oil condition monitoring and is expected to play a significant role in a more economic and environmentally friendly usage of oil.

This paper presents a new MEMS varactor that uses repulsive actuation to achieve an ultra-linear capacitance-to-voltage response. The approach proposed involves actuating the moveable electrode away from the fixed electrode, instead of the conventional closing-the-gap direction. This increasing-gap movement reduces the capacitance as the actuation voltage increases. The MEMS variable capacitor is fabricated using PolyMUMPs technology and exhibits an excellent linearity factor of 99.7% in capacitance-to-voltage response, and a capacitance tuning ratio of 11× was achieved. The proposed strategy will enable the development of high-performance MEMS-based tunable devices for various applications.

This paper presents a low power autonomous system to prevent the spread of nosocomial infections within hospital environment. It employs two combined techniques which are the (1) 868 MHz radio frequency and (2) 40 KHz ultrasound waves. A wearable device for hospital staff and a main unit ensuring coverage for all bed's surroundings have been designed. The wearable device consists of a radio transceiver and an alarm actuator while the main unit consists of a processor, radio transceivers, directional antennas, and ultrasound-based distance sensors. When the main unit detects and identifies a medical staff, it populates the identified information to an online database. In case the approached patient is already infected, the wearable device worn by staff activates an alarm. To reserve the battery power of the wearable device, an RF wake-up sensor is designed. The RF module of the wearable device will gain a new feature to be a hybrid (active/passive) device with a current consumption as low as 0.5 μA at 3 V supply. Furthermore, the main unit enters a power saving mode by disconnecting power from the distance sensors until a personnel approaches an area of contamination.