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Topics Covered
Overview
The Large-Area Sensors Business Today
The Case for Large-Area and Printed Sensors
Applications for Large-Area and Printed Sensors
Military and National Security Applications
Environmental Monitoring
Biomedical Markets
Robotics
Pervasive Computing
Smart Packaging
The Reality of Printing Sensors and the Alternatives
Large-area sensors are sensor arrays fabricated together on a substrate, often a flexible substrate. This distinguishes them from the garden variety of sensor, which is typically a single chip or chipset. The inherent performance advantages of large-area sensors are the same as any other array. First, there is the extra redundancy because the failure of one sensor in the array doesn't disrupt the entire array. Second - and in practice more importantly - large-area sensors provide for enhanced accuracy. his may be because the input from a sensor array can take the form of an average from all the sensors in the array, thereby factoring out anomalies. Or it may be because sensing over a large area speeds up response time in some critical way. A soldier in a uniform embedded throughout with sensors that can pick up on the first trace of a deadly toxin is better equipped and more secure than one who simply carries an individual sensor device around with him. The latter may detect the toxin only after the soldier is dead.
Large-area sensors are typically associated with "printed sensors," or at least printed sensors of a certain kind. Actually, the term "printed sensors" is somewhat ambiguous, perhaps deliberately so. Many sensors use screen printing for the deposition of electrode materials and have done so for many years. Although this kind of activity in one way or another generates large revenues every year, it is a mature area that hardly represents an opportunity in the usual sense of that word. There is another kind of printed sensor, however, and this is a sensor in which functional printing is used to create the entire sensor. It is this second kind of printed sensor that we are largely interested in here.
The connection between large-area sensors and printed sensors of the second kind is that printing potentially provides a way to create large-area sensors in a low cost manner; we are, after all, talking here about printing onto a flexible substrate, something that printing is very well equipped to do. Printing is also well suited to create multiple layers; in fact this is what functional printing is really about. This means, at least in theory, that layered sensor products can be created with functional printing. This may mean no more than the fact that both the sensing layer and the electrodes are created with printing techniques. But this fabrication concept may also be extended to producing sensors with multiple sensing layers, so that the sensor can sense multiple things. This multi-sensing function is one of the main trends in the sensor industry today and, as such, printing is in sync with bigger trends in sensing.
With all that said, there is no unbreakable link between large-area sensorsand printed sensors. Large-area sensors could be created using the conventional deposition and patterning processes found in the semiconductor industry; vapor deposition and photolithography, for example. Or at the other end of the manufacturing technology maturity scale, one could imagine large-area sensors being created using the tools of nanoscale engineering. However, the prospect that printing will enable large-area sensors to be created at low cost, coupled with the fact that printing is obviously a mature technology seems to ensure that the association between large-area sensors and printing is and will be a strong one.
To date printed and large-area sensors have played second fiddle to other developments in thin-film and printed electronics. Thus, the latest developments in this field have already spawned substantial new companies and internal projects by major multinational companies producing solar panels, displays and even RFID tags. Although the processes and materials that are used in fabricating large-area sensors are very similar to those used in these other areas, it is hard to point to the same level of economic activity in large-area sensors as one finds in these other areas. Indeed, NanoIdent, a commercial firm that tried more than any other to give printed sensors a try for a year or so, has now gone out of business. And, even a cursory review of the literature on wide-area electronics quickly indicates that much of the most interesting work in this field is being carried on in university labs. With all this in mind, a cynic might conclude that large-area sensors are a fanciful and futuristic idea whose time has yet to come around and that such sensors have no near-term commercial importance.
Nonetheless, NanoMarkets believes that such a conclusion would be a false one, and that there will soon be significant business opportunities in the large-area and printed sensors sector. For a start, we believe that the large-area sensor business should be judged by the standards of the sensor industry, not by other thin-film and printed electronics businesses. Thus, the sensor industry as a whole is very fragmented, with many rather low-key, medium sized firms that are often not well known outside of their specialized community of customers and suppliers. Therefore, one should not expect the large-area sensor business to be filled with the large, high-profile firms that one sees in the e-paper, OLED or thin-film solar panel segments.
In fact, when one begins to list the firms that are already active with actual products in the world of large-area or complex printed sensors and combine them with the names of the industrial labs that are making serious efforts to commercialize such devices, the final tally of names is quite impressive. This tally would include - but certainly not be limited to - Agilent, Collotype Labels, Cypack, Frank Sammeroff, Future-Shape GmbH, IMEC, PARC, Peratech, plastic electronic, Sony and VTT. Most of these names are not exactly familiar ones in the average household. However, they are the sort of firms that characterize the sensor industry as a whole.
With a little digging, one realizes that real products do exist, or are at least heading toward commercialization, that fit into either the large-area sensor category or one that involves printing to create more than just electrodes. This certainly adds credibility to this emerging sector, but is hardly a business case in itself. After all, history is littered with stories of clumps of firms that forms a community of interest around new technology and maybe even brought a few products to market, only to see their dreams fly out the window.
NanoMarkets believes that large-area sensors are different in this regard mainly because large-area and advanced printed sensors seem to have a very broad range of potentially high-growth applications. At the same time, the latest developments in functional printing seem to provide a way to fabricate such sensors at low coast. The combination of these two facts suggests the possibility of a class of sensors that are both novel and with large and fast growing markets. The novelty of such sensors means that there will be good opportunities for suppliers to establish sustainable advantages in the form of proprietary manufacturing approaches and intellectual property.
This kind of sensor shows little likelihood of generating large revenues in the next couple of years. However, what makes us so bullish on this sector is that these sensors seem especially well suited to - and therefore likely to strongly penetrate - some of the fastest growing segments of the sensor market, which in turn we believe are driven by larger socioeconomic forces. While these segments of the market are all very different in terms of their business characteristics, they need similar kinds of large-area and printed sensors.
This means that the cost of developing these sensors can be amortized over a wide range of large applications and that firms supplying the basic sensor subsystem can sell into multiple segments. Of course, a sensor firm may also choose to move up the value chain and capture more of the value added by offering more complete products specialized for a particular application or user segment.
There are three general areas where we believe printed/large-area sensors could command a large market in the next five years or so. These are identified below.
Large-area sensors of various kinds seem extremely well suited for protecting large public buildings from terrorist threats as well as for use in military uniforms at a time when security concerns are heightened throughout the world.
Large-area and low-cost printed sensors have potential for broadening the coverage of government and private environmental monitoring efforts. In particular, they are likely to serve as important components for the next generation of smart buildings. Thus, these sensors can be seen as an essential part of the "green tech" trend, which in itself is useful to sensor suppliers for market messaging.
Defined broadly enough this is already the largest market for printed sensors, because both diabetic test strips and DNA assays are already printed. The latter application is especially important because DNA testing is assuming a growing role in our society and because a new wave of biological testing based on proteomics is about to take over. In addition, large-area sensors are a vital component for the emerging product/market categories of smart bandages and human enhancement. Many of these opportunities for sensors are being driven by the needs of aging populations in the developing world.
These are by no means the only applications in which we see a market for the kinds of sensors discussed here. They have been considered by major aircraft firms to provide additional comfort and safety for passengers, for example. There are three areas that seems to present longer-term opportunities for advanced printed sensors and large-area sensors. These are:
In the past four or five years, personal robotics in the form of robotic lawnmowers and vacuum cleaners has shown itself to be a sustainable source of revenues. In addition, and in Japan especially, impressive humanoid robots have been built as companions and concept products. Sensors are inevitably a part of robotics and large-area and printed sensors may have a special role to play in robotics; printed sensors in the form of lowering costs and large-area sensors in the form of smart skin technology. Robotics could be the next big technology revolution, akin to the PC revolution in its ability to generate new business. But this revolution is not likely to occur for several years.
There has been much talk in the last five years of a new kind of computing that involves the "Internet of Things," in which smart objects are connected over Internet like networks. As with robotics, printed and large-area sensors could play an important role in this sector. However, it seems to us that pervasive computing is still some way from proving itself commercially, so the size of its potential for generating sales of sensors remains to be proved.
This is another area that still has to prove itself. There already seem to be some niches where smart packaging can make economic sense. Two examples are compliance packaging for pharmaceuticals and packaging designed to ensure the authenticity of branded products. Typically in the smart packaging area, cost points are very important and printing may help with that, especially since printing is already intrinsically a part of the packaging industry.
Printed electronics is either a new business or an old one, depending on how one defines the term. Thus, screen printing has been used for many years to create electrodes, membrane switches, capacitors, PCBs, etc. In these cases, printing was used almost as a coating technology or for the creation of large features. The new form of printed electronics, which has mostly emerged in the last five years, is intended to create complete devices with relatively small features, including sensors, although sensors has not been the area where most of the focus of printed electronics has been.
Both kinds of printed electronics are important, because of the more established areas of the printed sensor business (e.g., DNA assays) use printing in a traditional way. However, the new kind of printed electronics seems to offer the potential for fabricating complex sensors at very low cost points. In addition, as we have already noted, printing seems a natural fit for creating sensors in a large-area substrate.
This is the dream anyway. However, the new kind of printed electronics has had teething problems and has not arrived as fast as expected, a fact that needs to be considered in assessing the future of printed sensors. The current thinking on printed electronics is that initially printing will be used only for certain layers of making a device; the idea of creating a device entirely with functional printing has been put off for a while.
The term "printed electronics" typically refers to either screen printing, inkjet, or flexo/gravure processes. Functional inkjet has received a lot of attention because of its cited ability to create very small features and this fact could make inkjet highly suited to fabricating sensors. Flexo/gravure are very high throughput processes and are therefore suited to diabetic test strip products.
There are in fact dozens of different kinds of printing and almost all of them have been tried at one time as a means of fabrication for electronic devices including some sensors. One is perhaps worth a special mention here because it seems to have special relevance to sensors; this is transfer printing. In transfer printing, semiconductor devices are created using the conventional processes of the semiconductor industry. Then the devices are lifted off an existing rigid substrate and onto the flexible substrate. This process may be particularly suitable to sensors since it potentially enables high-performance arrays to be created on a flexible substrate, while, at the present time, more conventional printing methods tend to produce products with limited performance.
The mention of the semiconductor industry processes raises the question as to whether any of the processes used in this industry are appropriate to creating large-area sensors. The answer is probably yes, but only in the cases where performance trumps cost. And then finally, there is the possibility that some of the advanced tools of nanotechnology, such as nanoimprint lithography (NIL) or dip pen nanolithography (DPN), may have a role to play in the markets.
Source: Sensors: New Kid on the 'Printed Electronics' Block
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