# Unpowered sensors, the wave of the future?



## a_majoor (15 May 2006)

In Technology review, there is a short article outlining developments in sensor technology adapted from radio frequency identification (RFID) tags. Like the ones in the store, they are powered by the radio energy emitted from a RFID reader, but rather than just triggering the security alarm, the devices can have various sensors attached. Now in the current form, these tags need to be within a metre of the reader to power up and transmit data, but in time the sensitivity of the chips can be increased and the power requirement decreased so potentially the chips could be scattered by an artillery shell or scattered by patrolling soldiers, then activated and read from a distance by a remote sensor (perhaps carried by a micro UAV or mounted on a surveillance vehicle). An interesting line of research with lots of potential uses.

http://www.technologyreview.com/read_article.aspx?ch=infotech&sc=&id=16864&pg=1


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## MdB (30 May 2006)

If I understand well, the specific purpose of this sensor is to take a live/real-time measure otherwise out of reach of current sensors (because they can be integrated to a specific "body"). Concerning medicine application, this could help emergency operations in field hospital to have a wide range of state of body on the spot (even in the field).

Excellent website btw. Another military technology, check this out: Cloaking Breakthrough.


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## warrickdll (31 May 2006)

An unpowered sensor would be extremely limited in its uses. The article does mention ambient energy, but even this has limitations since some sensors require steady power levels. 

A more likely scenario, in the near future, would be to continue having batteries for a device's sensors and data storage, and then incorporate the RFID technology to power data transmission (a battery draining activity).


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## a_majoor (9 Jun 2006)

The main idea here is that there may be a way to provide extra "eyes on" in an inexpensive and easy to use format with some R&D work. If it is possible to create "smart dust" and sprinkle it over an area of interest, then interrogate it by using a reader device, then the soldier on the ground will be able to suppliment his or her own observations over a greater area of space or time. 

Even if the reader can only say a person was here one hour ago, it could be enough to provide warning of IED placement or a suicide bomber lurking in the area. More likely, the sensors would be in mixed batches, so some would say a person was here, others would report chemical residue, others would report on cell phone activities and so on, allowing a mor comprehensive picture to emerge. All this information still has to be integrated in the mind of a soldier, so training will hae to emphasize discriminating the signal from the noise.


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## vonGarvin (9 Jun 2006)

Interesting idea.  I would love to peek five years into the future to see how it works (and to get some lottery numbers)


PS: I note the ironic title


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## warrickdll (10 Jun 2006)

a_majoor said:
			
		

> ...
> Even if the reader can only say a person was here one hour ago, it could be enough to provide warning of IED placement or a suicide bomber lurking in the area. More likely, the sensors would be in mixed batches, so some would say a person was here, others would report chemical residue, others would report on cell phone activities and so on, allowing a mor comprehensive picture to emerge.



Chemical Residue detection is a familiar example of an unpowered data collector. Stick a detection patch onto your suit. And when you see a specific change in colour, you will know that there has been an exposure. 

This is also a good example of the hurdles that would be involved when trying to read that patch remotely and with the only the transmitted power from a reading device. How do you know when the detection took place? How can this information now be transmitted? 

If the exact time isn't important then the first problem is negated. Perhaps the area is swept regularly by low flying UAVs or robotic ground vehicles (or perhaps a simple form of material degradation could be measured). And converting analog information into a transmittable digital format is common - with power.

But if the sensor required is complex, or there is a need to store more than one point of data, unpowered would be more and more impractical





			
				a_majoor said:
			
		

> ...
> If it is possible to create "smart dust" and sprinkle it over an area of interest, then interrogate it by using a reader device...



This is a good idea, but trying to get small RFID tags onto/into the targeted equipment or supplies (or people themselves) could be something that could be done in the near term (these tags would be inert - their presence is all the information being sought).


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## warrickdll (11 Jun 2006)

Seems on-topic.



			
				tomahawk6 said:
			
		

> http://www-bsac.eecs.berkeley.edu/archive/users/warneke-brett/SmartDust/
> 
> http://siliconvalley.internet.com/news/article.php/3098551
> 
> Smart Dust is thought to have played a role in the tracking of certain members of Al Qaeda-Iraq that culminated in the bombing of Zarqawi.


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