

Open source Arduino pulse sensor looking for funding - webmonkeyuk
http://www.kickstarter.com/projects/1342192419/pulse-sensor-an-open-source-heart-rate-sensor-that

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inoop
Note that there is a wireless standard for interfacing with biosensors called
ANT+ (www.thisisant.com). You can get a USB stick for $30, and a heart-rate
strap for $35-40. Most Sony Ericsson Android phones come with ANT+ integrated
as well.

So I'm not sure what this adds to the what is already commercially available
other than Arduino integration and maybe the fact it's slightly cheaper?

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kiba
Cheaper is good. Hack-ability is good.

~~~
inoop
> Cheaper is good.

ANT+ stick is $30, about the same as a 'duino. No idea about the price point
of the sensor itself, but maybe $15? So you save $20, lose the wireless
connection, and gain a painful earlobe. I'm not saying it's a useless concept,
but I think it's applicability is _very_ limited indeed.

> Hack-ability is good.

What is more hackable about this versus ANT+?

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Futurologist
heart rate straps like the polar or garmin attach to the chest and require
skin contact. This is not always desirable if you are, say, sharing the
sensor, or engaging in casual (not athletic) use. Your BOM above does not
account for the heart-rate strap signal receiver. Add $15 for the Polar Heart
Rate module at Sparkfun, or $60 if you want it on a PCB. Plus the engineering
and lashup time. (full disclosure: I'm one of the Pulse Sensor Creators) The
Pulse Sensor outputs analog waveform based on blood oxygen content with some
people the waveform shows systolic and diastolic components. Heart straps will
only send out one ping per beat. This Pulse Sensor may have some limitations.
It may get noisy if you're being really athletic, for example, and it might
not like being drenched in sweat. But for that it's applicability is very
unlimited indeed. Specially if it's coupled with ANT+.

~~~
inoop
> heart rate straps like the polar or garmin attach to the chest

FWIW, Garmin also makes watches with built-in hart rate sensors and ANT+
integration, although these are rather pricey ($100 including USB stick).

> and require skin contact. This is not always desirable if you are, say,
> sharing the sensor, or engaging in casual (not athletic) use.

Doesn't your sensor also require skin contact?

> Your BOM above does not account for the heart-rate strap signal receiver.

The USB stick I mentioned is $30 from Amazon. The strap is $35, also from
Amazon (prices are similar for co.uk). This is assuming a wireless 2.4GHz
heart rate -> PC interface without a 'duino in the loop.

> Add $15 for the Polar Heart Rate module at Sparkfun, or $60 if you want it
> on a PCB. Plus the engineering and lashup time.

I'm not talking about Sparkfun, I'm talking about off-the-shelf stuff you can
buy from Amazon.

> (full disclosure: I'm one of the Pulse Sensor Creators)

I thought as much :)

> the Pulse Sensor outputs analog waveform based on blood oxygen content with
> some people the waveform shows systolic and diastolic components.

What kind of applications do you have in mind for this? I doubt you'll want to
measure blood pressure with this thing, it's wildly inaccurate and if I
understand correctly, blood pressure varies throughout the body. It also
doesn't really change over short periods of time?

> Heart straps will only send out one ping per beat.

Like I said above, I don't think this sensor is doing much more than that, but
I might be wrong. I mean, it's a neat way of doing it for sure, but I don't
think you should try to sell it as anything more than a low-cost heart-rate
sensor, and maybe a trendy earring :)

> This Pulse Sensor may have some limitations. It may get noisy if you're
> being really athletic, for example, and it might not like being drenched in
> sweat.

I believe you guys designed it for MMI, so I don't really see much of a
problem in that. Besides, everybody knows nerds don't like to work out anyway.

> But for that it's applicability is very unlimited indeed. Specially if it's
> coupled with ANT+.

I think your sensor is useful for hobby projects because of its low cost and
simplicity, and because it can easily interface with 'duino. I could certainly
see it being sold on SF or a similar site. I can also see it used in
installations where a user inserts his/her finger into a slot to influence the
visuals for example.

~~~
Futurologist
> Doesn't your sensor also require skin contact? Yup, but it doesn't need to
> be strapped tightly to the user's chest. A near impossibility if you are
> sharing with nerds ;)

Your suspicion of our audience is correct. We don't want to compete with the
overly saturated excersize-pulse-rate gizmo market. We see every year our
students at Parsons Design + Technology department curious about using heart
rate data in a project. We hope this will appeal to entry level and seasoned
hackers who want an affordable way to play with biofeedback. The answer to
'what kind of applications' is to look out the window and wonder.

The data that you get from the sensor is variable voltage based on (relative)
oxygen level of blood. In the video on kickstarter site, at about 1:20, the
waveform you see on the computer screen is raw analog data from the sensor. It
is passed directly from an arduino into a processing sketch, which serves as a
visualizer. Just thought of an application: Use the fluctuating waveform from
the sensor to modulate a tone, say, or make beats.

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inoop
> Just thought of an application: Use the fluctuating waveform from the sensor
> to modulate a tone, say, or make beats.

Fair enough, that's pretty cool I guess.

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yellowbkpk
If they used a red/IR LED pair instead of a single green LED they could sense
oxygen concentration as well as heart rate. The absorption spectrum for
oxygen-enriched blood is different in the two wavelengths. Toggle between the
two LEDs fast enough and you'll only need a single light sensor, too.

~~~
Futurologist
Yes, blood oxy is easily derived that way, but we were not interested in
making a device that had that level of medical accuracy and application.
(maybe in future version...?) We just wanted a simple heartbeat sensor with
simple interface for hackers. That said, you can get relative blood oxy
concentration. A couple of deep breaths will shift the waveform up ~20 points
on our visualizer, for example.(I'm a co-creator of Pulse Sensor)

