Arduino Shield – prototypes were assembled and tested this past week, and the results were good – no major, or even minor, issues were found.  The production versions of the PCBs were finalized, and orders were placed for PCB printing, components, and assembly.  The supply chain took longer than expected to establish, but things are rolling again now!  FlexVolt Arduino Shield Units should arrive around the end of March.  Assuming no issues in quality control and testing, these units should then quickly ship to fulfill pre-orders in the first week of April.

FlexVolt USB/Bluetooth – Patient protection, sensing circuitry, shielding, and power management are now finalized.  Next is packaging – how the PCB fits in the enclosure, and custom machining of ports for USB and lead wires.  Prototypes will be ordered this week for assembly and testing.

Lead wires – custom lead wires were designed, including an injection molding tool.  The tool is made, and prototype lead wires should arrive this week for testing.

In the last week of January, 2014, after the Kickstarter project ended, FlexVolt Pre-Orders became available through the webstore, and product development continued to reach the goal of shipping consumer versions of FlexVolt by April (March for Arduino Shields and initial production and testing units).

In the first week FlexVolt reached over $3,000 in pre-orders!

The first 3 weeks in February have been very busy, but were mostly devoted to fine-tuning the electronic designs and establishing the supply chain.  A lot goes into producing a consumer product!  Here are a few of the items worked on:

  • Patient safety isolation – Complete isolation between the computer and the user prevents any abnormal power surges on the computer side from coming through the USB port.  This includes digital isolators for power, ground, and signal lines, transient voltage suppression at lead connectors, and current-limiting resistors in-line with all lead connectors.
  • Supply Chain – making a one-off device is quite different from sourcing leads, electronic components, PCB printing, PCB assembly, and enclosures for even low-volume production!
  • Arduino Shield PCB – prototype done and arriving from the PCB printing facility (OSHPark for prototype boards) any day for in-house assembly and testing!
  • Bluetooth Design – Choices made for battery type, battery charge/discharge control circuitry, and power-path management (i.e. turning bluetooth on/off, charging the battery, or running on USB for both power and data communication)
  • Custom-made leads – re-designed as plug-in sets to make leads easy to remove, add, or swap.  Shielding added to help reduce 50/60Hz noise as well as other noise found in most homes these days.
  • Programming – lined up outside help for phone app development for Android and iPhone, developed and documented communications protocols (still need testing prior to public release), began to standardize functions and roll them into object classes in preparation for building a library plugin

I’ve received many great comments, either through the website or through email, ranging from requests/suggestions for specific features to offers to help with development!  As work transitions from working on the hardware and electronics to finalizing software, expect to see more open-source style activity, including software posts and establishment of user/developer forums!

Of course, please feel free to post or email any requests/suggestions/comments you may have!



What would make FlexVolt even more fun and convenient to use?  If it could send data to your computer (or smart phone!) wirelessly.  Now that is possible!

FlexVolt can now come with Bluetooth capabilities.  Check out the kickstarter page for the new rewards.  Details:

  • Power:  Li-Ion battery, rechargeable button cells – small but powerful!
  • Lifetime:  Minimum 3 hours of continuous measurement
  • Charging: USB
  • Battery management:  overcharge protection, undervoltage protection (this is critical for battery life in Lithium batteries!)
  • Data transfer:  Bluetooth, or USB if connected.  User-selectable.
  • Compatibility:   Mac, PC, smart phones, tablets (apps for Android coming soon!)
  • Bluetooth protocal : Bluetooth Specification v2.0+EDR (enhanced data rate)

Here’s a short video demonstration of transferring data over Bluetooth to a Mac:


I tested FlexVolt for use in EKG as well, after several questions about potential to use FlexVolt to measure heart signals.  While it is not a 12-lead EKG, I do get nice signals from my heart, similar to signals seen using a 3-lead EKG.  I have electrodes at left and right shoulder and left abdomen near bottom rib.  Pretty cool to watch the spikes:

Several people have asked about measuring eye movements with FlexVolt.  EOG (electrooculography) is the measurement of the electrical signals generated in and around the eyes due to contraction of different muscles controlling gaze direction.  So I placed electrodes above and below my eye, with the body reference connected to my left shoulder (I was previously testing EKG).


Looking up produced a positive bump, and looking down produced a negative bump!  Blinking is also apparent in the signal, but fortunately a different shape compared to eye movement.

What we’ve been up to:

July-September 2013: Groundwork – Initial research, electronics design, and prototyping. We started with an oscilloscope, a bread board, and an arduino!

September-November: Product Development – After many bread board iterations, we transitioned from bulky breadboard prototype to PCBs. We’re now on version 4.0 for the USB FlexVolt. We also used this time to work on firmware and software applications. We now have betas for several apps.

November-December: Business Development – We now have a business model, economic analysis, images and videos, and a kickstarter page. We are ready to launch!

We have a website up and running now – we can start posting details about FlexVolt, and eventually this site will host user and developer forums, as well as a web store.