I need a cost sensitive, reliable, durable motion sensor to track if a baby is breathing or not. This is for use in a university challenge project I hope to win. Any advice on my options are very welcome. [edit]

criteria to be followed

  • My project should be cost sensitive
  • should be low power
  • Should be easy to use by untrained personel


closed as not a real question by Brian Carlton, Dave Tweed, Olin Lathrop, embedded.kyle, The Photon Nov 11 '12 at 5:39

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    \$\begingroup\$ What is the actual set of criterion you have to follow? What are you allowed to do? What aren't you allowed to do? \$\endgroup\$ – Toby Lawrence Oct 26 '12 at 18:34
  • \$\begingroup\$ @TobyLawrence: I edited question to answer criteria \$\endgroup\$ – Dr Deo Oct 26 '12 at 18:44
  • \$\begingroup\$ You still didn't really answer my questions. Are you not able to have the sensor touch the baby at all? Does it have to be a certain distance away from the body? etc etc \$\endgroup\$ – Toby Lawrence Oct 26 '12 at 18:48
  • \$\begingroup\$ @TobyLawrence: There are no fancy restrictions like not having the sensor touch the baby. Although a solution that is contactless if cost sensitive would be nice :) Even having a plate that a baby can lie on to detect breathing should be fine. \$\endgroup\$ – Dr Deo Oct 26 '12 at 18:53
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    \$\begingroup\$ How about detecting something else? There are baby monitors out there already, as noted in my answer. But are there "pee and poo" detectors out there which can raise an alarm if a baby needs changing? (I don't know; haven't done the googling.) Just think of the creativity you can exercise to come up with a demo for such a thing. "Now, I'm gonna need a volunteer of reasonably small stature from the audience ..." \$\endgroup\$ – Kaz Oct 26 '12 at 20:13

Such motion sensors are commercially available. They have a transducer that takes the form of a large, flat pad. This is put under the bedding, and the infant lies on top of it.

It is coupled to some transmitter that will activate an alarm on a receiver if the transducer stops detecting movement.

So, that is what the successful, commercially available product looks like.

A good starting point would be to survey these, get one, and take it apart.

In a university challenge project, you don't have to beat a product in the marketplace, but of course whatever you come up with inevitably does get compared with what is out there.

All products have limitations because removing all imitations means skyrocketing cost. If you could find one or two limitations of the existing product and improve on them, then you have a "story".

Sometimes it's enough to improve on some limitations while introducing or increasing others. From the point of view of a consumer who cares about the limitations you improved, and does not care about the worsened ones, this is an improvement and in the market as a whole, it represents a broadening of the available choices.

Do not think you have to monotonically improve something; just making different design trade-offs is interesting.

  • \$\begingroup\$ Do you have a link for me to a manufacturers website, sir? \$\endgroup\$ – Dr Deo Oct 28 '12 at 3:48

Sounds like a non-trivial project! Especially with regards to the signal processing to eliminate breathing signal from other movement and noise.

Have you considered using a low-power infrared laser? Think: long-distance optical mouse. If you are an electrical engineer this would probably require teaming up with a physicist with basic experience in optics.

Advantages would be:

  • contactless
  • could potentially be operated from a large distance (e.g. ceiling)
  • possibly relatively cheap if you can modify an existing optical mouse with suitable optics
  • can leverage a PC for prototyping advanced signal processing techniques before trying to implement them in a MCU

A technique called "Eulerian Video Magnification" is able to amplify the subtle motions of breathing and pulse. It may be enough that you can then use more traditional image processing techniques to detect if the baby is breathing.

If attaching a device to the baby is ok, you could use temperature sensors in front of the nose and mouth, similar to how this device (NasiVent Sleep Apnea Home Test) detects breathing to diagnose sleep apnea in adults: http://www.youtube.com/watch?v=u-ikLvzkg5g Cold air is drawn over the sensor during inhalation, and warm air blows out during exhalation.


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