Imec advances in wearable technology

Imec researchers made advances in 2015 supporting new wearable and ultra-portable technology in IoT, radar, flexible circuits, medical and related nanoelectronic applications. Silicon Semiconductor reviews their 2015 successes and where research is headed in 2016.

2015 was a busy year from imec researchers in Leuven, Belgium and throughout the international organization. Imec is renowned for its contributions to microelectronic and nanoelectronic technology that have already transformed daily living. Results of this collaboration are recounted in the following article prepared by imec researchers (Belgium).

Imec researchers are showing that the ability to wear or easily carry advanced diagnostic, sensor and actuator devices will define ways that people interact with technology and how it interacts with people. While many different devices are moving from labs into the marketplace, Internet of Things (IoT) devices are rapidly evolving; their wireless connectivity will be transformative. But great devices do nothing without power, so new generations of batteries are in development. Sensor technology capable of highly reliable and secure data transmission will also be key for clinical, home and business applications.

Some new and emerging technology is not wearable in the literal sense, yet advances in chip technology that make electronic devices flexible or ultra-portable also create possibilities to radically alter the way diagnostic, safety and monitoring equipment performs. Portability and interconnectivity are key to these developments.

As wearable and highly accurate portable sensing technology emerges, will we soon have hand-held blood analyzers that deliver immediate results that once took days? Challenges exist, and not everything that can be conceived will be created, yet imec's advances in 2015 set the stage for more exciting discoveries to come.

Detecting and dealing with stress using sensors is quite a challenge by Chris Van Hoof, Program Director, Wearable Healthcare and imec Fellow

Chip technology enables us to improve existing measurement and diagnostic methods for cardiac conditions, neurological disorders and other medical treatment needs. It makes the equipment more compact, more economical and more comfortable for the patient, too. In 2015, we carried out a number of projects in this area. You need to have the right expertise, but in itself, this is not the greatest challenge in terms of medical sensor systems.

What is the greatest challenge?

Developing new methods! For example, our research group is looking at how sensor systems can make a contribution in the diagnosis and/or monitoring of heart failure, stress, sleep apnea and head trauma. Working with medical specialists, we're examining which parameters are relevant and how we can measure them accurately. The difficult thing in all this is that the method has to be demonstrated and approved in trials with a sufficient number of patients. Which of course means that you need a robust and mature demonstrator "“ and that is by no means straightforward in the research phase. But it's not impossible: this year we succeeded in setting up trials for heart failure (30 patients) and stress detection (1,500 people).

In the area of sensor systems for lifestyle applications, there are all sorts of other challenges. These include genuine ease of use, the personalization of algorithms and the creation of convincing applications that help persuade us to change our behavior.

Most of the end user devices you find on the market today tend to be disappointing when it comes to accuracy. They are very good for checking whether fit people manage to do their 10,000 steps or cycle enough kilometers, but they are of no use at all for the other 90 percent of the population. For example, they are simply not accurate enough for measuring whether an elderly relative is getting up and moving about the house enough, or whether an overweight person is increasing his level of fitness by doing the extra exercises recommended by his doctor. Overall, current devices are not at all inspiring and don't actually anticipate your individual needs and habits.

Many of today's devices are in their infancy compared to mobile phones or other sophisticated portable technology. Truly useful devices will address peoples' actual needs, and help answer questions such as: how to use sensors to encourage older and obese people to exercise more? How can you get someone to stop smoking? How can you help a person to keep their stress levels under control?

We at imec and Holst Centre are confident that sensors can help to recognize habits and make adjustments to behavior based on the progress already being made to enable these capabilities. But it is certainly no easy task: not technologically, but also because psychologists and behavioral scientists tend not to be very familiar with modern technology. As a result, there is still some skepticism about whether or not sensors are of any value in changing people's patterns of behavior. We are currently working with some enthusiastic behaviorists from UZ Leuven and KU Leuven to investigate the usefulness of sensors for stress management.

One of the main problems with using sensors to change behavior is the personalization required for the sensors themselves. Take stress, for example, which expresses itself differently in each individual. One person may start sweating, while another gets heart palpitations "“ and so on. This is in stark contrast with heart rhythm measurements, for instance, where all of the signals are more or less the same. They are also well known and any discrepancies are clearly identifiable.

Personalized sensors and algorithms are needed to identify behavior correctly with any accuracy and then make adjustments. In practical terms, imec and Holst Centre took the first steps in 2015 to validate the measuring technique used for stress and to recognize people's habits and "˜trigger' moments using sensors and artificial intelligence technologies. In 2016, the emphasis will be on providing feedback, for example, to reduce stress. A project will also be started to help smokers quit their bad habit with a "˜virtual coach', which is what we also call our sensor approach. Because one thing is certain: if we were all to have a personal coach who kept an eye on us 24/7, we wouldn't have to make a list of New Year's resolutions any more. Or maybe we would "“ even if it was simply to pass them on to our virtual coach.

What if radar could recognise us from the way we walk? by: Wim Van Thillo, Program Director, Perceptive Systems

The future Internet of Things (IoT), with its intuitive applications, will operate based on a broad stream of data supplied by sensors placed everywhere. These will be sensors that are many times smarter and more sensitive than the ones we have today. They will also be produced and installed in far greater numbers and be much cheaper than they are now. One example of such a sensor is radar, a simplified version of which is already used in high-end automobiles to enable the vehicle to take over a number of tasks from the driver. Current radar sensors still much resemble the radars that are used to regulate aircraft flight paths and see traffic. They are mostly manufactured using specific SiGe (silicon-germanium) technology. The resulting sensors are rather large and expensive, which makes them unsuited for unobtrusive integration into applications such as self-driving cars or drones.

At imec we develop radar chips based on CMOS technology. Ultimately, our aim is to arrive at a compact radar-on-chip, a chip that offers far greater performance at a much lower power consumption than is the case at the moment "“ plus we want to incorporate a number of additional features and capabilities. For example, over time, we envisage a radar that is capable of distinguishing pedestrians from cyclists. That technology might even allow identifying individuals by the way they walk. Making that radar, based on what we already have developed today is our challenge for the years ahead.

Over the past three years we have been working on the building blocks for just such a radar-on-chip using 28 nm CMOS technology. So far we have developed an effective 79 GHz transceiver, which in 2015 we also integrated with antennas on a micro-PCB.

The result is a fairly complete radar system measuring just a few square centimeters. The next step in our program is to make those building blocks even better, with additional features and an even better resolution. And at a system level, we plan to develop applications that far exceed the capabilities of today's radars.

One of the ways to make our radar sensor smaller and more sensitive is to work with an even higher signal frequency. Which is why, in 2016, we will start to develop the building blocks for a 140 GHz radar. We will be using even smaller antennas integrated onto the chip itself, resulting in an enhanced Doppler resolution and a better depth resolution.

In parallel, we are implementing smart signal processing for 79GHz and 140GHz systems.

The reflected signal received by our radar not only contains information about the position of the objects around the radar, but also about their movements. This "micro-Doppler" information makes it possible to distinguish pedestrians from runners, cyclists or animals. It might eventually even be used to distinguish individuals from one another. So, for instance, a car would be able to identify its driver and allow access based on the radar information.

To make this micro-Doppler information accessible, we will deploy algorithms for pattern recognition and automatic learning, algorithms that are currently used in image processing. With these our radar will learn to recognize and distinguish the micro-Doppler signature of individual objects. In a subsequent stage, we will then combine the signals

of multiple radars to create a full 360-degree image of what is going on around the car. Finally, to make the picture more complete and even smarter, our aim is to combine the radar information with that of other applications such as cameras or ultrasonic sensors.

Each type of sensor has a field of application for which it supplies unique information, and image sensors are typically better at recognizing markings on the road or traffic signs. This "sensor fusion" is what we ultimately want to arrive at, with applications affecting many aspects of daily living including health, safety and quality of life issues.

Enabling IoT applications with more value by: Harmke De Groot, Senior Director, Perceptive Systems

There is a tsunami of connected smart systems coming at us, with millions of sensors that generate data and gather information about the world around us, ourselves, our movements, the things we buy, our health and so on. But how do we ensure that these systems are truly connected, secure, and deliver applications that bring real value for their users? That is the major challenge facing everyone involved with the Internet of Things (IoT). This challenge also includes a number of technical aspects for which imec and its partners are developing appropriate solutions.

The main technical issue is that all of these systems have to be properly and seamlessly connected with one another, regardless of how much they may differ. Imagine, for example, trying to connect ultra-efficient sensors, extremely fast and broad data flows, complex industrial infrastructures and privacy-sensitive medical devices. To do so, we still have to overcome scores of interoperability and network problems for which we need to devise technical solutions.

A second important challenge is ensuring that we have tight security for all those systems, paying particular attention to privacy issues. Obviously you don't want everyone to be able to view the data generated by your sensors. But at the same time you do want to have a home in which appliances are connected and interacting intuitively with all the people who live there. But who exactly are these people? Which applications can children access? And what to do with someone who comes to stay for just one night?

Third, we will want to combine all of the knowledge provided by our sensors and systems so that we can create smart, intuitive applications. All too often at the moment, the data gathered from sensors is simply displayed on a device, after which the application waits for some kind of input from the user. In the future, the application will be able to improve itself and its environment autonomously, based on the intelligent combination of all sensor feedback.

We also need to make our applications future-proof. Every solution that is based on the raw power of number-crunching will be overtaken soon by Moore's Law. But a sensor incorporated into a building may be required to operate for thirty years. Which is why we have to come up with smart concepts, e.g. in the area of security, that are not dependent on processor speed.

In 2015 for these reasons we built a development platform for distributed IoT applications, a platform on which applications can be tried out and simulated at an early stage. Everyone using the platform can also plug in their own sensors and transmitters, which is handy when it comes to testing concepts for networking and security, or for simulating what happens if an application is expanded to using 10,000 sensors. We are using the platform to set up partner consortiums on certain applications, such as the precise measuring of air quality.

We have begun working on R&D for security and privacy "“ an area that is relatively new for imec. For example, we are looking at solutions capable of using location to decide whether someone is allowed to access an application. This prevents the smart sensors and actuators in your car or home from being manipulated remotely. And in the area of secure hardware, we are examining how we can develop PUF solutions (physical unclonable functions) without making the ICs larger or more expensive. In 2015 we also continued working on highly sophisticated building blocks for communication in the future IoT. We are developing low-power sensors for specific applications, as well as a series of transmitters that cover the wide range of needs in the IoT (extremely economical, very flexible, high data rates).

What will be needed in five years' time by: Paul Heremans, Technology Director, Large-Area Electronics

Our task as a research center is to offer our partners technical solutions for their future applications, two to three product generations ahead in time. But when it comes to flexible electronics, the industry does not follow predetermined roadmaps that we can base our research upon. Therefore, the big challenge that faces us every year is to accurately assess what our partners will need in five years' time.

One of the technologies that we are pretty sure will be a winner, is an improved "˜haptic' user interface for displays. Haptic or kinesthetic communication are devices that recreates the sense of touch. While touchscreens have become standard these days, they don't give users any touch feedback; the screen simply feels the same wherever you touch it. But with haptic feedback, you can e.g. make users actually feel that they have pressed a key. One way of doing this is with a large number of ultrasonic sound sources embedded in the surface of the display "“ which will be a really nice application for our flexible large-area technology.

For a number of years now, we have been working on flexible chips. We have managed to produce electronic circuits and applications using the same technology developed to enable flexible displays. There is a sizable interest from the industry for these kinds of chips. But what we need to do now in 2016 is make sure that they are ready to be mass-produced, for example using the same infrastructure that is also used to manufacture displays.

Another important part of our R&D involves producing comfortable wearable electronics. We are working on applications that are incorporated into clothing, as well as on electronics worn on the skin.

In 2015 we succeeded in producing a T-shirt with a built-in LED display that is not only flexible, but that also stretches. These displays are still low-resolution, comparable to digital signage applications. But if there is sufficient demand, we will start developing a higher-resolution technology.

We also made progress with our comfortable health patches. The next generation will consist of a disposable patch with the electrodes that contact the skin, and a small reusable module in the form of a card that is inserted into the disposable patch and that contains a.o. the readout electronics. In 2016, we'll research how we can replace the vulnerable connectors to the readout electronics with a contactless design using our NFC (near-field communication) technology.

A large part of our efforts in 2015 was in the area of display technology. Our program on flexible display technology only started three years ago, yet we are already recognized as innovators. We have achieved this status by focusing on a number of key technologies where we really make a difference, e.g. the patterning of very small OLED pixels to produce high-resolution displays. We are also designing energy-efficient, high-quality pixel drivers, for which our partners show great interest.

One of the driving forces for innovation is the way we can mix and match technologies with the other areas in which imec excels. For example, we are developing infrared photo detectors to complement silicon image sensors. By combining these two types of image sensors, we plan to produce hyperspectral cameras with particularly broad-spectrum coverage. We are also looking into using thin-film transistors derived from our display transistors as switches in the CMOS backend.

Another fruitful example of a cross-domain development is with healthcare technology: by combining our flexible electronics with low-voltage sensors that measure health parameters, we can create some particularly useful health applications. Reversely, the CMOS engineers involved with resistive RAM, which also uses on oxides for the active layers, are looking at how to apply these in flexible oxide electronics, and perhaps even in future energy-efficient displays.

Such R&D that crosses the boundaries of different fields will keep on growing in importance!

Chip technology enables us to make medical instruments smaller, faster and more cheaply by: Peter Peumans, Program Director, Life Science Technologies

The Apple A9 chip used in the latest iPhones contains more than three billion transistors. That's pretty impressive on its own "“ but when you look at its price of around 20 euro, it becomes even more remarkable. For decades the chip industry has succeeded in offering more and more functionality at increasingly low prices. It is our aim to bring the enormous power of silicon-based chip technology to the life sciences, too.

Why would we want to do that? First and foremost to make medical instruments smaller and less expensive. In doing so, we can bring them within the reach of consumers. A good example of this is our project in which we integrate an entire medical laboratory onto a chip measuring just a few cm².

The chip will be capable of analyzing the molecules or cells contained in body fluids (DNA, proteins, viruses, blood cells, etc.) totally autonomously. This will make it possible to carry out sophisticated tests quickly in places where it was previously impossible: in the hospital ward, at a doctor's practice and even in the patient's home. As an example, DNA tests could become mainstream as a result.

A second reason for bringing chip technology to the world of the life sciences is to increase the speed or throughput of medical instruments. Imagine if you were able to read (or sequence) DNA using a chip. Then it would become possible to integrate a large number of these sequencing components onto a small area, enabling high throughput DNA sequencers.

Companies that specialize in DNA sequencing are truly convinced by the power of silicon technology. This is demonstrated by the partnerships that imec currently has with these companies (such as with Pacific Biosciences).

Chip technology is also of interest for cytometric devices (counting and examining cells) because the devices themselves can be made smaller and more compact (and hence become mainstream), or because their throughput is enhanced. Counting and examining cells may be of value, for instance, in following-up leukemia treatment: a disposable chip that could quickly count the number of blood cells would help the doctor to tell the patient on the spot whether the treatment is working.

Another application is cell therapy in which human cells are used as medicine. One risk with this treatment is that wrongly programmed cells might be injected inadvertently, which could lead to tumor formation. Cytometric devices are needed to be able to check all of the cells to be injected before they are administered to the patient. Thanks to chip technology, this can be done faster, better "“ and also cost less.

Imec's lens-free microscope technology can also be extremely useful in this area, too! Up until now, we have worked mainly with "˜older' chip technologies for the life science applications mentioned above.

More specifically with 0.18 and 0.13 micrometer technology on 200 mm silicon wafers. In 2016, we aim to go a step further and test scaled chip technologies. At the present time, no one knows what these more advanced chip technologies might mean for medical instruments. After all, if the "˜old' technologies already mean such a revolution for equipment manufacturers, doctors and patients, who knows what the newer technologies will bring.

The best electrolyte material for solid-state batteries hasn't been found yet by: Philippe Vereecken, Principal Scientist, Electrochemical Storage

These days, we all walk round with a smartphone and laptop "“ which has mainly been made possible by lithium-ion batteries. At the moment, these batteries still operate with a liquid electrolyte which limits miniaturization. The flammable liquid also poses safety risk especially for use in wearables and medical implants. But because we also intend using sensors just about everywhere in our environment soon, we need to find a worthy successor to replace it. And this is the solid-state lithium-ion battery. This new type of power unit will be more compact, as well as safer. And if you manage to combine this battery with thin film technology, it will also be possible to recharge that battery very quickly. This makes a handy solution for small batteries, which will always have a limited capacity. In a larger format, this battery would also be ideal for flexible electronics and who knows, eventually maybe even for powering electric cars. In fact, you could say that it is the holy grail of rechargeable batteries.

The main problem with solid-state batteries is that we have not yet found the ideal electrolyte. Of course, we have made plenty of progress in this direction "“ just look at the many scientific papers that have already been published on the topic. But the fact remains that the world of batteries is still not much further down the road than the first generation of lithium solid-state batteries of the type that are used in pacemakers, for example, which only deliver a very small amount of current.

Our research center (imec) is on a quest to find the best electrolyte material for solid-state batteries. We are currently focusing on composite electrolytes. There are two other types of electrolytes that could meet the needs, but they still have quite a few disadvantages. The first of these types, polymer electrolytes, do not have sufficient conductivity. The second, inorganic electrolytes, require a high process temperature, which results in the electrodes becoming damaged.

Last year, we succeeded in developing a composite electrolyte that not only has good conductivity (2x10^-4 S/cm), but is also compatible with the materials used for electrodes (lithium-manganese-oxide as a positive electrode and lithium-titanium-oxide as a negative electrode in our lab). This electrolyte is made mainly from silica, a material with which we have a great deal of experience in the chip industry.

Now the challenge is to combine our 3D electrodes and our silica-based composite electrolyte to produce a genuine 3D thin film solid-state battery. If everything goes to plan, we will have a first demonstration set ready in 2016. And hopefully we will then be able to demonstrate that 3D thin film solid-state batteries are more than just hype and are a real new step forward in battery technology that will enable us to produce ultra-small electronics and batteries that will recharge in no time at all!