Self-Powered Sensors Send Out Signals with No Power Failure Combining Energy
Technology with Sensor Networking
Katsumi Fujimoto
General Manager,
Product Development Dept. 2,
New Technology & Products Development Group,
Technology & Business Development Unit
Fujimoto joined Murata Manufacturing in 1981 and engaged in developing piezoelectric filter, resonator,
and actuator products. In 1989, he started to concentrate on developing piezoelectric vibratory gyroscope
technology to the mass-production phase and in the course of time he worked in Kanazawa and Toyama. He was
transferred to the Device Business Unit in 2006 before assuming his current office in 2008. Fujimoto is
convinced that optimistic and flexible thinking and indomitable perseverance are the keys to successful
development. His favorite pastime is woodworking. He changed the room layout and finished the interior of
the second floor of his own home—all by himself.
Murata is now strengthening its commitment toward developing environmental and energy technologies.
Electric power can be generated not only at large power plants, but also from energy sources at home and
work, and in cities and towns that have been largely ignored in the past.
Representing the ultimate in environmental responsibility, energy harvesting is now being put to practical
use.
Microenergy Enables Sensors to Send Out Signals with No Power Failure
This new technology exploits microenergy resources available in our everyday environment to drive a
sensor network. Energy sources such as sunlight coming into your home, water temperature differences,
pressure generated as you turn a switch on or off, or the vibration of a car body can generate 100 to
500µW (microwatt=10-6 watts) of power, which can be used to activate sensors and send out
signals by radio. Energy harvesting technology enables Murata sensors to power themselves with no
conventional power supply, cabling, or batteries. Once installed where they are needed in your office or
home, they send out data indefinitely with no power failure.
Exploiting Human Activity to Power Human Movement Sensors For Optimized
Lighting and Air-Conditioning
The movements people make when they open a door to enter a room, for example, can be exploited to
generate the power required to switch on specific lights. The central control system detects which doors
are opened and which rooms are being used, monitors human movement, and adjusts air-conditioning to
concentrate on occupied space. Once a room is left unoccupied, the system turns off the room's lighting
and air-conditioning. Data on such uses are processed using a PC and controlled by cloud computing. This
technology is advanced in Europe and has been introduced in many buildings.
In Japan, we have yet to see its full-fledged introduction and have only reached the point where energy
control has been visualized. Murata has started trial operation of a self-powered wireless lighting
switching system introduced at the head office of Toda Corporation, a construction company. Using wireless
technology makes it possible to achieve non-directional lighting control and eliminate cabling, which
helps reduce installation costs. With this technology, we now aim to develop new business in the building
remodeling market.
Energy is not inexhaustible. This is why I believe that the energy harvesting
concept, which is designed to minimize power consumption, represents the ultimate in environmental
compatibility.
Creating New Businesses Through Cross-Organizational Interaction
The Murata "MIRAI" initiative is aimed at creating new businesses through cross-organizational
interaction. Here, interested individuals get together in cross-organizational projects to commercialize
world-first products, ideas likely to attract customer interest, or practical moneymaking concepts. The
MIRAI initiative helps Murata engineers, who have been weak in the "horizontal development" of their
technologies, to create new businesses by cross-organizational exchange. The first MIRAI project concerns
energy harvesting.
It first started with 8 members, and they met 2 to 3 times every month for product development. The
completed product was premiered at trade fairs such as CEATEC JAPAN, where it generated positive market
response.
Self-Powered Sensor Network Aiming for Operation at the Nanowatt Level
Sensor networking represents one of Murata's traditional strengths. The technology's self-powered concept
not only makes it maintenance-free, but also allows us to install it almost anywhere. Current technology
performs the sensing and communication functions by generating µW levels of power. On the frontier
of research, scientists have already entered the next phase, where they are striving to enable operation
at the nW level (nanowatt=10-9 watts). To this end, it will be necessary to develop sensors and
communication modules that can work at nW power levels. This will in turn make it necessary to review the
choice of material and communication standards. We have very few competitors here, thanks to the high
standards of technology that are required; but the hardest part is getting customers to understand the
very concept of energy harvesting.
It consists of eliminating the use of artificially-produced energy and exploiting the inexhaustible
microenergy sources available around us. Traditionally, we used to calculate the amount of power required
to achieve certain functionality and then find the best way to supply that power. Energy harvesting goes
in exactly the opposite direction. It concerns how to make devices and modules that can work on low levels
of power available in the environment. I am convinced that it represents the ultimate in energy
conservation, which ensures comfort in our lives with no wasteful use of energy.
Scientist and engineers have made rapid progress in sensing, computing, and networking technologies. In
the human body, these are likened to the five senses, the brain, and the nerve system. Using these
technologies, modern buildings incorporate functions that imitate those of living beings. There has been
good progress in research into ways to make buildings work like human beings (biofication of buildings) . Nearly 50 Japanese companies have worked together to
establish the Energy Harvesting Consortium, and the market is finally bearing fruit. Murata is working on
product development with the aim of achieving 10 billion yen in net sales from this business in 5 years.
Biofication of Buildings
Science has made dramatic progress in sensing, computing, and networking technologies. In living
organisms, these functions correspond to the senses, the brain, and the nerve system. Using information
technology, modern architecture increasingly incorporates bionic systems and functions into buildings.
Biofied buildings automatically monitor damage as well as design and work failures, decide what repairs
are needed, and communicate this information to maintenance personnel. In the event of a major earthquake,
they can automatically give warnings to residents to speed evacuation. Developed and pursued by Prof.
Akira Mita at Keio University, the concept is closely connected with energy harvesting.
Self-Powered Wireless Lighting Switching System
This system uses electromagnetic induction to convert human movement used, for example, to turn light
switches on and off, into electric power and sends out wireless signals, activating 100V AC control
relays to switch lighting on and off. The battery-free wireless lighting control system allows for
easy maintenance, and the wireless concept reduces installation costs. It has been developed to meet
increasing needs in the building automation and remodeling markets. Murata has started practical trial
operation of this system at the head office building of Toda Corporation.