Design and implementation of a light-based IoT (LIoT) node using printed electronics

Abstract. The recent exponential growth of new radio frequency (RF) based applications such as internet of things (IoT) technology is creating a huge bandwidth demand in the already congested RF spectrum. Meanwhile, visible light communication (VLC) is emerging as a technology which can be used as an alternative wireless communications solution which makes no use of the radio spectrum. In addition, continuously powering up the massively deployed IoT nodes is becoming a challenge when it comes to maintenance costs. Development of energy autonomous IoT nodes would certainly assist to solve the energy challenge. Previous work shows that renewable energy sources can be utilized to address the energy requirement of IoT nodes. Under this context, we have developed a light-based energy autonomous IoT (LIoT) prototype. This thesis presents a feasibility study and proof of concept of LIoT, including design, implementation and validation of LIoT nodes and a transmitter unit. Furthermore, the ability of multiuser communication using VLC as well as indoor light-based energy harvesting were demonstrated and tested in this thesis. To make the concept of LIoT more attractive from an implementation standpoint, and to create a future-looking solution, printed electronics (PE) technology was used as a part of the implementation. Two key components of the prototype were based on PE technology, photovoltaic cells used to harvest energy, and displays used to exhibit information transmitted to the LIoT node. In the future, when PE technology becomes more mature, very low-cost, small form-factor and environmentally friendly LIoT nodes could be implemented on thin substrates. A wide array of possible applications can be created combining the concept of light-based IoT with printed electronics. The proposed LIoT concept shows great promise as an enabling technology for 6G

Dense and long-term monitoring of Earth surface processes with passive RFID -- a review

Billions of Radio-Frequency Identification (RFID) passive tags are produced yearly to identify goods remotely. New research and business applications are continuously arising, including recently localization and sensing to monitor earth surface processes. Indeed, passive tags can cost 10 to 100 times less than wireless sensors networks and require little maintenance, facilitating years-long monitoring with ten's to thousands of tags. This study reviews the existing and potential applications of RFID in geosciences. The most mature application today is the study of coarse sediment transport in rivers or coastal environments, using tags placed into pebbles. More recently, tag localization was used to monitor landslide displacement, with a centimetric accuracy. Sensing tags were used to detect a displacement threshold on unstable rocks, to monitor the soil moisture or temperature, and to monitor the snowpack temperature and snow water equivalent. RFID sensors, available today, could monitor other parameters, such as the vibration of structures, the tilt of unstable boulders, the strain of a material, or the salinity of water. Key challenges for using RFID monitoring more broadly in geosciences include the use of ground and aerial vehicles to collect data or localize tags, the increase in reading range and duration, the ability to use tags placed under ground, snow, water or vegetation, and the optimization of economical and environmental cost. As a pattern, passive RFID could fill a gap between wireless sensor networks and manual measurements, to collect data efficiently over large areas, during several years, at high spatial density and moderate cost.Comment: Invited paper for Earth Science Reviews. 50 pages without references. 31 figures. 8 table