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29 May 2014

Photonics for sensing: short list of 18

For as much as sensing technology is already enhancing our lives, the future promises even more.

Take that smartphone, for example.

Currently, it contains several very useful sensors. But, noted Tim Day, CEO/CTO of Daylight Solutions during a session on “The Future of Sensing” at the recent SPIE DSS event in Baltimore, by 2020, it’s easy to envision hundreds of sensors on such a device.

Demands for personal fitness monitoring and personalized medicine are big drivers, Day said.

Today’s sensors can tell us a lot. For example: How quickly did I go from jog to sprint today compared to yesterday? How close am I to my destination? What is that constellation?

But we want to know much more: blood sugar levels, temperature, blood pressure, air quality, and on and on. And we will be able to, via wearables (see Scientific American on that topic) and other technology using photonics.

Thermal images captured with Opgal's smartphone
attachment can be presented in a variety of color
schemes as above, or in black-and-white.
Looking at what’s in or close to being available to the consumer now, at the SPIE DSS Expo FLIR and Opgal were showing thermal-imaging attachments for the smartphone that can be used, for example, to find water leaks, assess tree damage, locate inflammations under a pet’s fur, or detect people or animals moving around outside a building.

In another aisle in the Expo, the Applied Physics Laboratory at Johns Hopkins University demonstrated the first major upgrade in prosthetic limbs since World War II -- with the help of a prototype robot called Robo Sally. The robot was fitted with modular prosthetic limbs with tele-operated feedback controls, using technology initiated with significant investment from DARPA. (See a video demonstration of Robo Sally.)

video
The prosthetic system includes electrodes in nearby muscles that pick up signals from the brain, enabling the amputee patient to activate the hand. While functionality varies from person to person depending on when and where on the body the injury occurred, the prosthetic provides a high level of dexterity. The grip is sensitive enough to pick an egg without breaking the shell, yet firm enough to grasp heavy objects.

On Robo Sally, the arms can be operated remotely as well from up to a half mile away, fulfilling tasks such as bomb disposal or checking chemical spills.

Looking further into the future, food safety is another area where sensors – specifically, using hyperspectral sensing -- have a lot to offer.

Moon Kim of the U.S. Agricultural Research Service, in a conference presentation in the Sensing Technologies and Applications (STA) symposium, and David Bannon, Headwall Photonics, in the “The Future of Sensing” session told how. (Scan the news from SPIE DSS 2014 for synopses of Moon's and other papers from STA and its sister symposium, Defense + Security.)

Agricultural food products can be contaminated with pathogens at any point in the growing, harvesting, packaging, and preparation processes.

In a paper co-authored with Colm Everard of University College Dublin, Moon described using hyperspectral imaging techniques to monitor food and detect pathogens in greens and other vegetables.

Bannon’s list of applications included mandated poultry inspections, looking for histamines in fish, and removal of foreign objects such as glass or metal during processing.

A laser-based sensing system for detecting gas leaks has been monitoring the millions of miles of natural gas pipelines in the United States for the last two decades. In another conference paper, Michael Frish of Physical Sciences described a similar system his company has developed for application in the CO2 pipelines that are used in extracting oil and natural gas.

The detectors may be permanent or mobile, even deployed on UAVs (unmanned autonomous vehicles), or they may be open-path sensors that stand guard at intervals along a pipeline. When a leak is detected, these wireless, solar-powered sensors will generate an alert within one minute.

Frish said that the version now being tested at various locations is expected to become an important tool as the movement of carbon dioxide expands with carbon sequestration and increasing use of hydraulic fracturing, or fracking, in oil and natural gas extraction

This quick list includes 18 applications of photonics-enabled sensing. Read more about optical sensors in the April issue of SPIE Professional.

What applications for a better world do you see at work or on the horizon?

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