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Topic: Relaxino (Read 3 times) previous topic - next topic


Back in the stone age, one of the more interesting classes I took was Behavioral Medicine- this was in the 80's, when the whole biofeedback thing really actually gained a bit of legitimacy.  Since you already have skin resistance and there plenty more inputs, maybe youcould add in more sensors..

Oxygen saturation is a good one, sat can drop due to anxiety.. And with the same detector (IR pair on fingertip works I understand) you can determine heart rate and respiration rate.  If you've been in an ER recently, they put one of these on you.  Work great and non invasive.  A few searches should yield some info on how to implement.

THEN, you can implement session data storage and upload to PC via serial, where the data can be graphed and trended...

Products like these, though relatively simple, really do work well and can even help change things for you, medically, in the long run!
When the testing is complete there will be... cake.


I was at Uni in the 80's. Pre-web-istory and the fax-age !

They did put a sensor on my finger. I think, as you say, you can sense O2 and heat rate on the finger. I saw an article for the CES show in Las Vegas had medical sensors for mobile phones and some of these used the type of sensor you mention. Skin resistance sounds good.

I'll look at other sensors too for measuring stress / relaxation. Blood pressure comes to mind, but the devices used on me were really annoying, and involve arm-squeezing devices, motors etc...

I wonder if you can sense the pulse in the carotid artery made by the heart beating, and somehow calculate the energy in the wave, and correlate that with instantaneous blood pressure?  There seems to be quite a tangible displacement in that pulse.

I don't want to go the whole hog and make a lie-detector type device, but there must be something in between.

Craig Turner, blog: http://gampageek.blogspot.co.uk/ It helps with my learning if I write things down, esp. for others to follow (constructive comments welcomed to improve)


Well, "lie detector" was a misnomer from the start, and is of dubious value in many cases.  Was another subject covered in the class.

The proper name- polygraph- is not a negative in any way, however- and is quite accurate a description.  It graphs (reads, stores, writes, manipulates, etc) poly (multiple) physical properties of the body.  The whole idea of it being a lie detector was that if you lie your stress level increases,  and can be sensed.. Obviously a flawed idea from the start.  Sociopaths and psychopaths both feel no stress when lying,, and those are who you are trying to catch.

Biofeedback is an awesome subject, and leads you down a lot of cool thought paths that can even be prototyped with our favorite little toy,...

One warning though, must be made.  Take EXTREME care when dealing with electricity and the body.  One mistake can kill.  Everything battery powered, no mains,  isolated as much as possible,  measure every voltage and current at every contact point to make sure, etc etc etc.  I'm sure there's a few darwin awards that started out as tinkering, don't become one!    :D
When the testing is complete there will be... cake.


I'm completely new to ardiuno and i got a project to build a spring stretch (displacement) meter.This is achieved by altering the frequency of oscillator circuit to which spring is attached, acting as an inductor. The inductance varies with the stretch of the spring attached to the circuit. Microcontroller is programmed in such a way to count the frequency and display the corresponding displacement on the LCD. i have made the oscillator circuit now I need help with programming the ardiuno. please let me know. i would be grateful.


Feb 05, 2013, 12:45 pm Last Edit: Feb 05, 2013, 01:07 pm by trendski Reason: 1
Hi Mansoor,

I'm sure there will be people to help, make a new topic in the sensors section:


spring stretch (displacement) meter

Attach a circuit diagram and picture of your spring and device

Craig Turner, blog: http://gampageek.blogspot.co.uk/ It helps with my learning if I write things down, esp. for others to follow (constructive comments welcomed to improve)

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