New connected sensors will detect anything, anywhere

Toni McConnel
iApplianceWeb

Sensors are usually invisible and silent and they are everywhere—in our cars, in every room in the house, in every factory, office, restaurant, and theater, in space craft and submarines, in our pockets or worn on our bodies—and they can detect just about anything you can think of, even at a molecular level: gases, radio waves, light, heat, electrical impulses, fluids, microbes, pressure, smoke, sound, movement. Coming soon is a sensor that will even detect bad breath! They are as simple as the bulb in your toilet tank that turns off the fill valve when the water reaches a certain level, and as sophisticated as the nanosensor that can be injected into the blood stream to detect one particular disease germ and no other.

As ubiquitous as they are now, you ain’t seen nothin’ yet, for shrinking form factors, lower production costs, wireless connectivity, and new battery technologies have been opening up applications for sensors that weren't thought to be possible or practical a very short time ago. And now there is an ambitious plan by the Department of Defense (DoD) to create a Global Information Grid (GIG) that will interconnect, wirelessly, virtually every individual in the DoD, the military and the intelligence community no matter where on the globe they might be. The GIG will also track most, if not all, materiel for those services, and do it reliably and securely.

Sensors play a key role in the implementation of the GIG. Low-cost, low-power, ad hoc peer-to-peer mesh networks, for example, will be used to record and report a myriad of conditions in the war space, including detection of movements by the enemy and the presence of biowarfare substances. In addition, every soldier will be wearing a bevy of sensors to enable them to receive and send information between themselves, vehicles, aircraft, and other soldiers. Some of the sensors will monitor a soldier's body for physiological wellbeing and make that information available to medics who may be many miles away. Much of this work will require "intelligent" sensors.

Even disregarding military applications, sensor networking is an explosive growth area in industrial and home markets, with many of these networks also connecting to the Internet. Estimates of the ratio of Internet-connected devices to Internet-connected people by 2010 range from 1000:1 to 100,000:1.

The prospect of supplying the demand for sensors for both government and commercial markets has triggered an immense amount of research and development. $21 billion has been budgeted to be spent on the GIG alone between now and 2010. Regardless of whether the GIG succeeds or fails (prior DOD projects of this type, such as Milstar, have been costly failures), the companies that develop products to meet GIG requirements are taking little risk because there will be innumerable commercial applications for the new technologies.

Zach Kaplan, president of Inventables, a firm that helps companies come up with barrier-breaking new ideas, believes that using intelligent sensors at the edge of the network will also stimulate innovative ways to interface with it. As an example, Kaplan points out that Logitech has used a textile with embedded switches to create a roll-up QWERTY keyboard. It's easy to imagine the convenience of such a device used in a battle arena to communicate with a PDA-like device. When not in use, it can be rolled up and stowed in a pocket. "If designers will learn to think out of the box," says Kaplan, "in the future we'll see things like cell phones embedded into the sleeve of a jacket..."

However, there are enormous challenges to be faced to produce sensors and sensor networks that will meet DOD objectives, particularly in the mesh networks, where sensors must be power independent for months and even years; the radio range/power expenditure ratio has to be greatly improved while size must be minimized. Above all, interoperability is a sine qua non. If everything in the system is not interoperable, there simply is no system. When you're talking global scale operations, the challenge is daunting. The same challenges exist for systems in the commercial sector, where extended wireless sensor networks will be deployed to monitor such things as utilities, environmental conditions, and manufacturing.

Open standards are a top priority

Interoperability depends primarily on open standards, of course, and of the many standards relevant to networks, those related to communications are the most crucial. Robert L. Mayberry, vice president of IBM's Sensor and Actuator Solutions, says "There needs to be continuity in communications all the way from the designer's desk to the machines on the factory floor, from there to the shipping platform and the warehouse, to the retailer and even to the consumer. Soon, all the devices in that network, whether wireless or wired, will be involved in decision making based on the real-time accumulation and analysis of information by actuators monitoring sensors."

A discussion of all the standards existing or in development for wireless networks is too complex to include here, but two of them require comment: RFID and ZigBee.

In June of 2005, IBM announced incorporation of radio frequency identification (RFID) technology into its Websphere middleware. The idea is to deliver on-demand asset management and more efficient supply chain management to sites remote from the enterprise, such as retail stores and distribution and manufacturing centers. Sun Microsystems also offers RFID middleware based on its open Java Enterprise System and is developing auto-ID products, and Wal-Mart Stores is incorporating RFID into its supply chain management. Support from these three giants certainly means that RFID has a solid niche.

However, market analyst Kristen West (West Technology Research Solutions, or WTRS) is worried about too early adoption of RFID. "RFID has some fundamental problems," says West. "There are some industry-specific standards that are not compatible or in any way transferable to RFID. And RFID frequency allocation has not been uniformly allocated across the globe. Thus there are very few frequencies available on a global basis for RFID technology."

As for ZigBee, the ZigBee Alliance ratified the ZigBee specification in December of 2004, and made the specification public in June of 2005. According to Alliance market studies, three billion ZigBee-compatible devices will be sold in 2007. Although ZigBee, too, has some drawbacks, it has many strengths that make it a prime contender for use in mesh networks. "ZigBee architecture is simple, inexpensive, small and self-contained, and its power requirement is nominal," says West. A detailed comparison of the strengths and weaknesses of wireless standards is available in the report "Wireless Sensor and M2M Markets" published in May 2005 by WTRS.

DARPA is supporting major programs to develop advances in protocols. One is investigating new protocols and physical layer chips to achieve, among other things, a 300-fold reduction in energy for low duty cycle connectionless networks. Another program is neXt Generation Communications (XG), which aims for a 10-times increase in spectrum access by automatically scanning the airwaves in real-time for available spectrum in which it can set up and tear down ad hoc networks in hundreds or even tens of milliseconds.

Internet Protocol version 6 (Ipv6)

The present Internet Protocol, version 4 (IPv4), will not support the future world of connected devices because IPv4, which uses 32-bit address lengths, has a limit of about 3-4 billion URLs it can support. However, IPv6 is a 128-bit address protocol, and will provide support for about 340 undecillion (10 36) IP addresses, or about 430 quintillion (10 18) addresses per square inch of the earth's surface. Every human on the planet will be able to have an individual, permanent IP address--like social security numbers on a global scale--and so will every animal, appliance, electronic device, and any other thing that needs to be located or that needs to send and receive data. Universal adoption of IPv6 is inevitable, and since China received only about 2 percent of the URLs available under IPv4, it is way ahead of the U.S. in adoption of IPv6. The DOD has decreed that all of its networked devices will use IPv6 by 2010, and as the GIG goes, commerce will follow.

MEMS and Nanotechnology

Kay drivers of innovation for sensors are microelectromechanical systems ( MEMS) and nanotechnology.

MEMS devices combine, on a single chip, the computational ability of microelectronics with the sensing and control capabilities of microsensors and microactuators. These devices can be measured in micrometers, and the technology has allowed production of network sensors no bigger than a grain of rice and miniscule power requirements. They are ideal for sensing, measuring, and reporting mechanical, thermal, biological, chemical, optical, and magnetic phenomena and then, based on the data collected, actuators can initiate appropriate actions such as moving, positioning, regulating, pumping, filtering, and so on. DARPA is looking to MEMS technology “to bring enhanced levels of perception, control, and performance to weapons systems and battlefield environments" and is investing heavily in research which, again, will be easily adapted for commercial applications.

Nanotubes are carbon molecules only one or two nanometers wide and about a millimeter long. They are potentially capable of distinguishing a single molecule and have almost negligible power requirements. Nanotubes have a huge potential in defense as well as in medical and environmental applications. DARPA is funding research in this area as well.

As an example of current MEMS development effort, Kebaili Corp., which specializes in chemical sensors, is working on a MEMS-based hydrogen sulfide sensor for NASA. The sensor is 1 x 1 x 0.38 mm, and will be used in spacecraft to detect bacterial activity, or "biofouling", which must be rigorously controlled. Kebaili's sensor has a power consumption of less than 25 mW, and can detect hydrogen sulfide in quantities as low as one part per billion, using a palladium-nickel alloy thin-film sensing element. The innovation Kebaili has introduced is a method of nanostructuring the alloy to increase the surface of the alloy without expanding the physical dimensions of the device, thereby increasing the detector's sensitivity.

The power/range conundrum

A lot of work is being done to find alternatives to batteries for power, and many new techniques for “energy harvesting” are appearing. One of these uses the natural electrical fields of the human skin to power Personal Area Network devices. This isn’t a new idea, but evolution of the technology has been hampered by the difficulty by limitations of signal range (in centimeters) and bandwidth. Signal "noise" from various electromagnetic waves has been a problem, as well as limiting network power needs to what can be produced from the skin. However, in April of this year Nippon Telegraph and Telephone Corporation (Japan) announced field trials of RedTacton, a device in which they have used lasers and electro-optic sensors instead of electrical sensors. The RedTacton prototype communicates at 10Mbps, and does not suffer the interference from other wireless devices that plagued earlier efforts.

On another front, EnOcean GmbH (Oberhaching, Germany) won one of the Best of Sensors Expo Awards in June of this year for their STM100, a solar-powered wireless sensor module. Up till now, producing enough solar power to operate sensors in size-restricted applications has required solar panels that use too much real estate to be practical. EnOcean's breakthrough was to design a device that requires only 200 lux to operate, and can store enough energy to operate up to five days in complete darkness. In addition, the transmitter will send a signal up to 300 meters outdoors, or 30 meters indoors through walls.

On the horizon is the use of engineered biomolecules to manufacture photovoltaic (PV) solar power cells with dramatically increased performance and affordability over current PV technology. Research efforts in this direction are being supported by DARPA.

In-body radio

Research is also extremely active in its search for new uses for sensors in medical applications, especially for devices implanted in the human body, and of course monitoring the physical condition of warriors remotely is a crucial interest of the DoD, so here again, DoD requirements will ultimately benefit civilian interests as well.

Although those devices are becoming more and more intelligent, getting information out of the body is a major challenge. In response to this challenge, Cambridge Consultants Inc. has developed an intelligent low-IF (intermittent frequency) radio transceiver, SubQore, for in-body medical diagnostic and therapeutic use. It has an average current draw of <1 µA and <1.7 mA peak for a 0.05% duty cycle, 400 Kbps bidirectional communications application. Used with a pacemaker, a lithium cell will give the radio a life span greater than 10 years. Implantable pacemakers, defibrillators, remote telemonitors, orthopedic devices, pump controllers, nerve stimulators, and ingestible imaging and diagnostic systems are some of the possible applications for the SubQore.

Andrew Diston, managing director of CC’s USA office, states “The magnetic coils presently in use are not adequate to send the amount of data that physicians now want to collect from implanted devices. Radio can handle more data and get it out faster. A device by the patient’s bed can receive the data at night while the patient is sleeping and transmit it to the doctor’s office.”

Diston identifies two major challenges that stand in the way of speedy development of these advanced technologies. One is the problem of antennas for the radios. “Designing antennas to transmit from a human body is like trying to transmit in a bucket of salt water. Also, if you have a highly tuned antenna, then small changes in the environment have a dramatic effect on the performance of the radio.”

The other challenge, says Diston, is the expense of long development cycles and the necessary clinical trials. “The expense and the resources required keep all but the major players out of the market.”

Mo Kebaili agrees, from the perspective of MEMS research and development. "The cost of developing a MEMS device is high because it requires a clean room environment. Only the biggest companies can afford to do it unless the company can get venture capital or a grant from DARPA or NASA. Eventually there will be desktop clean room environments where the user is outside and inserts his hands in gloves to manipulate items in the box. But until that kind of tool is available, the expense of necessary equipment is prohibitive for small companies."

The journey vs. the destination

Some critics have said that the GIG is an unrealistic and costly project that is bound to fail. Regardless of whether they turn out to be right or not, government grants for research to realize the GIG’s objectives are supporting a healthy climate of innovation for companies large and small—you can ask Mo Kebaili. Kebaili’s hydrogen sulfide sensor is an excellent example of how research on technologies originated to serve the military/space sectors can be turned to profit in commercial markets. Kebaili used his life savings to start his project for NASA, but is finishing it under an SBA Small Business Innovation Research grant.

Kebaili says “Once the NASA project is finished, we plan to adapt the same technology to make a two new devices. One will detect bad breath, which produces higher than normal levels of hydrogen sulfide. The other will be used in medical research to detect nitric oxide levels in asthma patients. Both devices will be about the size of a Chapstick, and in the case of the nitric oxide device, can replace equipment costing many thousands of dollars.” For entrepreneurs like Kebaili, it won’t matter much if the GIG turns out to viable or not.

But if it succeeds and is ultimately opened up to public use, as the Internet was, the effect on everybody’s daily life will be enormous. We will be able to connect to anything, anywhere on earth, if we are authorized to do so and own a PDA or cell phone. I asked Vint Cerf, known as “The Father of the Internet” for his role in its development, if he thought this is a possibility. “ I think it is doubtful that the GIG would ever be opened to public use,” Cerf said. “It has a specific purpose. The Internet was opened up in part for economic reasons, but in my view these would not operate in the same way for the GIG.”

I hope he’s wrong (although it might be a historic first), but even if he’s right, the perfection of wireless and sensor technologies in quest of the GIG Grail will benefit us all, beginning now.

Toni McConnel is executive editor of iApplianceWeb and writes the Security Sentinel column.  She is also a nature photographer and an award-winning fiction writer. You can reach her by email at Toni[at]TechRite-Associates[dot]com.