Low Cost Peel-and-Stick Wireless Sensors: From Prototype Development to Field Testing

September 18, 2018

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An estimated 200,000 devices are connected to the internet every hour across the globe. These devices rely on wireless networks for their communications. Developments over the past two decades in the field of wireless sensor networks are now being leveraged to enable widespread monitoring of physical and environmental conditions (e.g., temperature, indoor air quality, light, occupancy) in buildings as inputs into automated and optimized control of operations. The U.S. Department of Energy (DOE)’s Building Technologies Office (BTO) has conducted research and development (R&D) to harness these advances in wireless capabilities by exploring novel solutions in microelectronics and manufacturing techniques that will reduce cost and increase operational lifetimes compared to conventional wired approaches in the building energy management sector. One approach that BTO has invested in to help meet these goals is a platform from Oak Ridge National Laboratory (ORNL). This novel sensor package recently achieved a critical milestone in its development process, bringing it one step closer to enabling energy savings in buildings.

Background

“Every building is a prototype. No two are alike,” according to the award-winning architect Helmut Jahn. This concept can be applied to both the architectural design and the actual operation of a building. The diversity of equipment and components (e.g., heat pumps, LED lighting) installed within the building, along with the variability of the construction type, building use, and geographic climate affect real, operational buildings, including their energy performance. Variables such as occupancy preferences, weather patterns, and grid conditions also have an impact. Therefore, newly developed energy-efficient building technologies may perform in a certain way in the lab, but operate substantially differently when installed in the field. The process of field testing components is especially critical to the performance verification process so that building owners and operators understand and trust how new technology could impact their specific building. Without objective validation and verification, transitioning technologies out of the laboratory becomes more challenging. Results from field testing inform both further work necessary in the product design and development phases, along with potential new expansion of existing R&D.

Research History

Design of the ORNL wireless sensor platform started in September 2013. The ORNL team’s wireless sensor platform is designed to monitor multiple environmental factors within a building (e.g., temperature, humidity, light levels). In 2015, this project was transitioned into a cooperative research and development agreement (CRADA) with the electronics manufacturer, Molex, to manufacture prototypes and investigate scaling of the initial processing conditions. To date, two prototype versions have been developed that optimize the communication network performance to reduce networking infrastructure and improve energy efficiency.

In parallel, the team has been partnering with original equipment manufacturers (OEMs) in the buildings sector to identify design requirements for applications of interest. The modular design and peel-and-stick installation of the platform provides the versatility to customize sensors based on the monitoring variables of interest for the chosen application. Through separate funding from the BENEFIT FOA awarded in 2016, the ORNL-led team is also researching approaches to extend the lifetime of the on-board power source by improving the efficiency of the energy harvester and extending battery lifetime between charges, as well as optimizing the calibration process.

Field Testing

Based on the application-specific requirements developed with the interested OEM partners and in preparation for field testing, the team initially tested the manufactured sensors for three months during the summer of 2017 at the Flexible Research Platforms (FRP), ORNL’s unoccupied commercial building test beds. Monitoring data collected was compared to building instrumentation to validate the accuracy of the measurements made. Testing began this past fall of the manufactured sensors by two different partners at their test facilities and in real, occupied buildings.

SkyCentrics, a building management platform developer, tested environmental conditions (i.e. temperature, humidity, and lighting levels) using 20 of the sensors in their head office. These preliminary results are now being used to explore opportunities to integrate the technology with their platform. Pilot Flying J, the largest operator of travel centers in North America, tested 20 sensors at their headquarters building to evaluate network connectivity, reliability, and sensitivity of the sensors in an occupied, large commercial building setting (over 100,000 square feet) as a means to calibrate the building’s heating, ventilation, and air conditioning (HVAC) equipment. Ultimately, based on the collected results, the Pilot Flying J team believes the sensor platform will be beneficial in improving the efficiency of the commercial kitchens, HVAC, and refrigeration systems through more affordable and accurate monitoring of environmental conditions and equipment performance. Finally, the manufactured sensors have been installed in the refrigeration displays at ORNL’s FRP to monitor the temperature of the cases to ensure proper refrigerator performance and storage conditions.

Tristan de Frondeville, CEO of SkyCentrics, said, “We believe that low-cost sensors producing high-resolution data are vital to the development of real-time, data-driven, responsive solutions that minimize the lifetime cost of buildings, maximize occupant comfort, and minimize environmental footprint. We are excited to work with ORNL and Molex to help turn this vision into reality.”

The versatile design and processing conditions of the sensor platform have been developed to enable a low-cost, flexible approach for these test cases. The results obtained from these initial field tests will be beneficial to optimizing the system and strengthening these types of OEM partnerships. In fact, the team recently established a CRADA with SkyCentrics to solidify their partnership.

Next Steps

As federal funding for the early-stage R&D of the wireless sensor platform wraps up, Molex is investigating commercialization pathways for the ORNL-developed wireless sensor platform. Molex is collaborating with building automation companies such as SkyCentrics, as well as other OEM’s, on incorporation into their product line.