Light-Based IoT: Developing a Full-Duplex Energy Autonomous IoT Node Using Printed Electronics Technology

Abstract

The light-based Internet of things (LIoT) concept defines nodes that exploit light to (a) power up their operation by harvesting light energy and (b) provide full-duplex wireless connectivity. In this paper, we explore the LIoT concept by designing, implementing, and evaluating the communication and energy harvesting performance of a LIoT node. The use of components based on printed electronics (PE) technology is adopted in the implementation, supporting the vision of future fully printed LIoT nodes. In fact, we envision that as PE technology develops, energy-autonomous LIoT nodes will be entirely printed, resulting in cost-efficient, flexible and highly sustainable connectivity solutions that can be attached to the surface of virtually any object. However, the use of PE technology poses additional challenges to the task, as the performance of these components is typically considerably poorer than that of conventional components. In the study, printed photovoltaic cells, printed OLEDs (organic light-emitting diodes) as well as printed displays are used in the node implementation. The dual-mode operation of the proposed LIoT node is demonstrated, and its communication performance in downlink and uplink directions is evaluated. In addition, the energy harvesting system’s behaviour is studied and evaluated under different illumination scenarios and based on the results, a novel self-operating limitation aware algorithm for LIoT nodes is proposed.

Performance Evaluation of Carbon‐Based Printed Perovskite Solar Cells under Low‐Light Intensity Conditions

“…In brief, the harvested energy from an array of CPSCs (in the energy harvesting unit) was first supplied to charge a prismatic supercapacitor (Capxx 0.4F 4.5 V). [ 106 ] An Atmega 328p microcontroller [ 107,108 ] (in the TSN‐ECU) was selected as the TSN's controller component, which was programmed to function at a frequency of 8 MHz and voltage of 3.3 V to perform the operations between the TSN and optical wireless transceiver (OWT) [ 105 ] with minimum power consumption. In addition, an ultra‐low‐power step‐down DC–DC voltage converter [ 109 ] was used to provide steady voltage (3.3 V) to the TSN‐ECU (Figure 8).…”

“…Moreover, the bidirectional optical communication links were established between the TSN‐ECU and the DCU, which could be categorized as: a visible light communication link as a “downlink” (from DCU to TSN‐ECU) and an infrared communication link as an “uplink” (from TSN‐ECU to DCU). [ 105 ]…”

“…The active area was 0.64 cm 2 (large area). Finally, the capability of CPSCs is demonstrated by energizing a Light-based Internet of Things (LIoT) concept-based temperature sensing node (TSN) [105] by harvesting ambient light (1000 lux) energy through them from the FL light source. The setup was made by constructing three individual units, which can be categorized as: 1) Energy Harvesting Unit, 2) TSN Electronics Control Unit (TSN -ECU), and 3) Data Control Unit (DCU), as shown in Figure 8.…”

“…Moreover, the bidirectional optical communication links were established between the TSN-ECU and the DCU, which could be categorized as: a visible light communication link as a "downlink" (from DCU to TSN-ECU) and an infrared communication link as an "uplink" (from TSN-ECU to DCU). [105] Figure 9a represents the generated temperature data profile in response to the above-described experimental setup. The supercapacitor (Figure 9b) gets fully charged through CPSCs and maintained its operating voltage of %4.5 V during light harvesting intervals (i.e., illumination mode).…”

Towards truly sustainable IoT systems: the SUPERIOT project

“…The sustainable manufacturing methods of PE technology can allow cost reductions of more than 60% when compared with conventional electronic manufacturing methods [37]. As highlighted in [36][37][38][39], sustainability is related to many aspects of a product, including energy-and material-efficient manufacturing, use of materials from renewable sources, use of environmentally friendly materials, ecological design, use phase benefits, as well as support for recycling, reusing and repairing, among others. Despite the fact that PE has advanced notably in the last decade and today a great range of components and even complete systems can be implemented with printed technologies, the current state-of-the-art of PE technology is not mature enough to allow the implementation of a fully-fledged IoT node as defined in the SUPERIOT concept, e.g.…”