Arduino playtime, the world of sensors, and fantasy devices

Arduino lab documentation:

Potentiometer pics:

Initial experiments failed, I spent some time figuring out why.

Debugging my code:  When I turned my potentiometer, values 0 – 120 left the LED off, and 121-255 turned it all the way on.  Clearly, my potentiometer was working fine according to the serial monitor.  The code looked good.  Can you guess what the problem was?

That’s right, I had my LED output in a digital-only slot – pin 12.  I moved to pin 9 and everything worked as expected.

Potentiometer testing

Moving on to the pressure sensor required some extra work.  The leads on it are very thin and can fry easily, so I did not solder them.  Zeven advised some of us to clip apart a long header chip, and solder to the pins on a 2-pin chunk.  Which is what I did, after some practice*.  It worked well, the hardest part was cutting apart the chip – time to get stronger clippers!  Soldering was fun but the diy wire-based helping hands did not hold my wires tightly to each other, and I had to wait in the lab for the iron to cool down before I could put it away.  This convinced me I should get better helping hands and schedule more time around Arduino work.

Pressure sensor values read 0 to 986 so the trick above (divide by 4) gives you a max output of 244, not perfect.  Instead I used the map function: map(analogRead(A1), 0, 986, 0, 255).  (I used a variable for analogRead(A1) but this would also work)

Pressure sensor

*I practiced with coils of wire twisted to resemble higher-order protein structure.  Someday I want to make large-scale wire protein sculptures with “amino acid” protrusions carrying magnets, to simulate the +/- charges and how they interact.  Fun!

Sensitive surroundings:  Chelsea

A walk around my neighborhood to count non-organic sensors.

Card swiping for transit and purchases – ATM, MTA

IR remote – turning up the volume on a TV

Barcode scanner – UPS packages, shelf restocker

Pressure – mat in front of doors, car horns

Tilt sensor and touch sensor – iPad (held by child in stroller, so cute!)

Motion detector – in front of sliding doors, between posts in store, elevator door

Microwave/RFID read/write – Store merchandise security tags deactivated

Digital scale – Grocers, laundromat, FlavaBoom! (Pinkberry-clone)

Temp control – Coffee machine (Clover model at Cafe Grumpy), taxi AC

Pushbuttons – ATM, CELL PHONES!, cameras, elevator, credit-card scanner (taxi, retail), handicapped entrance (used by non-handicapped person), laptop/keyboard, registers, calculator for manual register, digital scale, barcode scanner, tv remote, portable game system (DS), microwave, pedestrian crosswalk

Sound – camera, cell phones, boom mike

Light – camera

GPS – unit in car, cell phone

WiFi detectors – phones, laptops

Accelerometer – cars etc

Fantasy Device:  The Waker-Upper

Many of us suffer from chronic exhaustion.  Sometimes, no matter how much caffeine you pound, you still sail off to Nod.  There must be a discreet way to head this off at the pass.

There are three ways currently in use to measure drowsiness: reaction time/accuracy, facial expressions and head movement, and EEG.  I would prefer EEG, assuming we can get down to a non-intrusive 2-point measuring system that does not need to be placed on the temples.  NeuroSky has one example of a simple system, but it is still extremely noticeable.  I found a few examples of simpler EEG setups.

EEG:  Alpha and theta  waves are a good measure of attention – they increase as your attention decreases.  Before you ever realize it is happening, a sensor could detect this (facial expressions yield predictions 60s prior, this should work faster.

A useful output device would deliver a discreet wake-up mechanism.  This could be directly attached to the sensors, to deliver a beep/small electric jolt/tapping to the skin, or wirelessly connect elsewhere.  A pressure cuff anklet could randomly squeeze the calf, startling you into awareness.

The Talk To Me exhibit displayed a particularly nice sensor-band meant for patient monitoring.  I imagine a similar device, approximately hearingaid-sized, could be placed behind each ear to measure alpha waves.

This would be useful not just for chronic daytime sleepiness, narcolepsy, jet lag, etc.  It could also be worn by drivers who need warnings that they are dangerously tired. Driver drowsiness is being addressed in many different ways, particularly with recent facial recognition software used to gauge head movements and expressions consistent with fatigue.   See for more.


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