BlueSense: designing an extensible platform for wearable motion sensing, sensor research and IoT applications

We present an extensible sensor research platform for wearable and IoT applications. The result is a 30x30mm platform capable of 500Hz motion and orientation sensing using 98mW when logging the data. The platform can wake up at programmed intervals using only 70uW in hardware off mode. A maximum 0.6ppm time deviation between nodes allows usage in a network for whole body movement sensing

Flexible IGZO TFT Spice model and design of active strain-compensation circuits for bendable active matrix arrays

The detailed measurement and characterization of strain induced performance variations in flexible InGaZnO thinfilm transistors (TFTs) resulted in a Spice TFT model able to simulate tensile and compressive bending. This model was used to evaluate a new concept, namely the active compensation of strain induced performance variations in pixel driving circuits for bendable active matrix arrays. The designed circuits can compensate the mobility and threshold voltage shifts in IGZO TFTs induced by bending. In a single TFT, a drain current of 1 mA varies by 83 µA per percent of mechanical strain. The most effective compensation circuit design, comprising one additional TFT and two resistors, reduces the driving current variation to 1.1 µA per percent of strain. The compensation circuit requires no additional control signals, and increases the power consumption by only 235 µW (corresponds to 4.7 %). Finally, switching operation is possible for frequencies up to 200 kHz. This opens a way towards the fabrication of flexible displays with constant brightness even when bent

Low temperature and radiation stability of flexible IGZO TFTs and their suitability for space applications

In this paper, Low Earth Orbit radiation and temperature conditions are mimicked to investigate the suitability of flexible Indium-Gallium-Zinc-Oxide transistors for lightweight space-wearables. Such wearable devices could be incorporated into spacesuits as unobtrusive sensors such as radiation detectors or physiological monitors. Due to the harsh environment to which these space-wearables would be exposed, they have to be able to withstand high radiation doses and low temperatures. For this reason, the impacts of high energetic electron irradiation with fluences up to 1012 e-/cm2 and low operating temperatures down to 78 K, are investigated. This simulates 278 h in a Low Earth Orbit. The threshold voltage and mobility of transistors that were exposed to e- irradiation are found to shift by +0.09 ± 0.05V and -0.6 ± 0.5cm2 V-1 s-1. Subsequent low temperature exposure resulted in additional shifts of +0.38 V and -5.95 cm2 V-1 s-1 for the same parameters. These values are larger than the ones obtained from non-irradiated reference samples. If this is considered during the systems’ design, these devices can be used to unobtrusively integrate sensor systems into space-suits

A flexible inductive sensor for non-invasive arterial pulse measurement

Arterial pulse measurement is a crucial indicator of cardiovascular health and prevailing techniques such as resistive force sensors, capacitive sensors and pulse oximeters possess challenges in wearability, continuous monitoring, and user comfort. In this paper, we present the development of a novel inductive sensor for non-invasive arterial pulse measurement. The proposed sensor incorporates high-permeability magnetic fillers into a flexible silicone based polymeric matrix. The sensor operates on the principle, that the permeability of the material changes in response to mechanical stress and possess high sensitivity. The experimental results revealed that the sensor demonstrates high linearity and sensitivity. The measured heart rate is compared to a standard clinical pulse oximeter (error $</p