SALs are a solution looking for a problem. There is nothing surprising in this. The laser and the smart card were in that state for twenty years before sales suddenly took off. The fuel cell was only commercialised over one hundred years after its invention. The Stirling Engine now looks as if it will sell well in a few years time but it has been nearly two hundred years in the wilderness. How can we speed things up with the SAL? After all, if we define a SAL as a label with a microchip and battery
, or more generally as something label-like with a transistor
circuit and its own power supply, then a few million are already being sold every year for monitoring the temperature of blood in transit and similar applications. Two billion blood samples and bags are made every year in the world so there must be more scope here as the costs come down.
At the other extreme it is a no brainer that self adjusting use-by dates that monitor when something has been opened and how hot it has been will be widely used one day. This SAL will show alphanumerics. Leave the milk in the sun and you will see the use by date scroll down until the bold word "Expired do not use" comes up, probably flashing and maybe with sound. They may become a legal requirement. However, they must cost no more than a few cents and the SAL industry is a million miles from that at present. It matters little whether the self adjusting use by date incorporates RFID
- that is just a matter of paybacks and specific needs.
More immediately, a fertile source of ideas for SALs comes from the active RFID market. IDTechEx has the world's largest database of examples of RFID in use and about 100 of the 850 case studies currently available concern active RFID. These vary from those where nothing is replaced, such as the billion dollars already spent on key fobs for remote locking of cars and many of the military applications, to conventional markets that have been around a long time such as tracking freight containers. Both sectors are growing fast but the ones that break new ground are often the biggest - a moral there for SALs. What can they do that replaces nothing? We can think of many things.
Another relevant observation is that active RFID projects tend to involve more money than passive ones, so although IDTechEx may continue to find that roughly one eighth of RFID projects involve active tags, the percentage of money spent on active vs passive systems including the tags is probably more like 20-30%. This may be true of RFID systems incorporating SALs despite the fact that the SAL tags are expected to be much cheaper than conventional active tags. Offsetting this is the fact that big systems are often likely to involve large numbers of SAL tags, even disposable ones.
What passive RFID tags can be replaced with active? Honesty is needed here. Any active RFID tag is bigger, shorter living and with more to go wrong than a passive alternative and it is more expensive. The many advantages may offset this but simplistic arguments that active is more reliable because it reads in more hostile environments are simplistic and can be counterproductive.
What problems are solved by today's active tags? Here the news is good in that they are very widely used to control prisoners, those on parole and the disoriented elderly and prevent mother baby mismatching and theft of babies in hospitals (just one breast feeding from the wrong mother can give a baby HIV AIDS). Active tags deter theft of laptops - currently running at about 800,000 yearly in the US alone. They protect sensitive keys from theft or misuse and let staff and assets be located and give alerts in hospitals etc. They track pipelaying, postal service performance and much else besides. In many of these applications a smaller, cheaper tag would be most welcome, but not if the battery shelf life, or the life in use, is only 18 months or so.
IDTechEx are optimists about SALs and see them as part of the reason why the yearly spend on active RFID systems will increase 3.5 times in the next ten years. Indeed, we see the non-RFID applications of SALs as even bigger and more accessible.