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1  Topics / Science and Measurement / Re: Heart irregularity monitor on: March 10, 2014, 08:13:59 pm
I see that the attachment doesn't open without downloading.  Please download it for pictures and examples or go to http://www.potomacmeso.com/heart-rhythm-monitor.html for more information on hardware and Arduino and Processing sketches.

Thanks
2  Topics / Science and Measurement / Heart irregularity monitor on: March 10, 2014, 08:09:32 pm
For  people with normal, regular (sinus) heart rhythm, the interval between heart beats is relatively constant.  However, many others (like me) sometimes experience irregular heartbeat rates, and the time interval between beats varies.  There can be many causes of irregular heartbeat, and it is useful to be able to monitor the degree of irregularity under various conditions, and sometimes helpful to look for patterns in the rhythm.  Using an Arduino Nano, an Easy Pulse sensor, and Processing I have built a heartbeat monitor that plots the statistics of the heartbeat inter-beat interval (IBI) showing the distribution of IBI's over a sequence of beats.  This gives measure of degree of irregularity. The system also allows listening to a speeded-up replica of the heart rhythm to detect rhythmic patterns.  The Arduino and Processing sketches are derived from those posted for the PulseSensorAmped sensor, since they were a better fit to the application than the Easy Pulse variants.

I found that it's important to either run the sensor from a separate power supply or clean up the output from the USB- supplied Nano 5V pin.  I used a 3.3V regulator to clean up the Nano 5V output and ran the sensor at the reduced voltage.  A single earbud driven by a Nano digital pin through a 330 ohm resistor allows listening to an accelerated version of the heart rhythm for a sequence of 100 pulses.
3  Community / Products and Services / Re: New Highly Miniaturized Arduino on: May 08, 2013, 04:45:47 pm
Yes, but we would first like to get more input from various kinds of users about what they need inside the miniature modules (MCU type, regulators, sensors, op amps, memory, etc.) and how they would like to connect to it (connectors, cable, solder contacts to a board, epoxy contacts to a board, etc.).  Comments and suggestions are always appreciated, either here or through our website, www.potomacmeso.com.
4  Community / Products and Services / Re: New Highly Miniaturized Arduino on: April 16, 2013, 08:59:55 pm
Thanks. 

We use a laser-based process in which narrow grooves and holes are engraved in a thin substrate and filled with nanoparticle silver paste that cures to solid silver at moderate temperatures.  Typical conductor widths are 15 micrometers.  These narrow conductors are easy to route between pads and under components to make miniature circuit modules using the smallest surface mount components.  Connections to the silver conductors are made with conductive epoxy. 

There is more detail on the module fabrication process in the publications on the download page at potomacmeso.com.  No photolithography or etching is involved and no lead is used so the process is pretty green.
5  Community / Products and Services / Re: New Highly Miniaturized Arduino on: April 04, 2013, 07:30:48 pm
We aren't selling these yet, but, if you have an application that needs a miniature Arduino, send me a note at www.potomacmeso.com/contact.  I'll try to get you something to work with.
6  Community / Products and Services / Re: New Highly Miniaturized Arduino on: April 03, 2013, 01:54:34 pm
Thanks for the feedback. 
I'm looking into ways to make the download a little smoother.  In the meantime, try right clicking on the download link and selecting "Save target as...".  After saving, change the file extension from .xml to .brd.  Then you should be able to open it with the v6 versions of Eagle.  This works on my system.  Let me know if you continue to have problems.
7  Community / Products and Services / Re: New Highly Miniaturized Arduino on: March 28, 2013, 06:58:49 pm
Thanks for all of the comments.  These are all good. 

A bottom view of the 10mm x 10 mm active module is shown in the attachment.  The connection pads are the staggered arrays on the left and right sides of the package.  The module resembles a big surface mount chip and there's more room inside for other components.  We've also built sensor arrays in the same modular format. 

In some ways these modules are like big ASIC's that can be mounted in several ways.  The second attached photo shows top and bottom views of a complete wireless sensor built around an Arduino module and an accelerometer module.  We used a 2.4GHz wireless module from Anaren here.  If anyone is interested in the Anaren/Arduino interface firmware we've posted it at www.potomacmeso.com and also on Github.
8  Community / Products and Services / New Highly Miniaturized Arduino on: March 23, 2013, 10:22:00 am
We've recently built a highly miniaturized Arduino (pictured below) that may be interesting to some of the members of this forum.  It's in the form of a 10mm x 10mm x 1.5 mm encapsulated module attached to a 25 conductor polyimide flex cable with conductor pitch of 0.3mm. 

The module includes an Atmega 328P chip with a 2.8v LDO regulator, an inverter that is useful for interrupt management, a dedicated I2C interface, an SPI interface and several other digital and analog I/O options. Schematics and an Eagle layout are available at www.potomacmeso.com. We built this setup for wireless sensing applications, but it probably would be useful in other areas where miniaturization is important. If there is enough interest, we may offer this as a product. Right now we're comp'ing a few of these to advanced users with miniature applications. 

Comments and suggestions are always welcome.
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