Hemoencephalography (HEG)

### DESCRIPTION

Hello, I'm a 24 yr old small time Alaskan engineering, computer science, and psychology enthusiast. Over the summer I reverse-engineered, updated, and simplified an important but not well known biofeedback device called an HEG, which stands for Hemoencephalography. It was developed in the late 90's to treat ADD, PTSD, and Depression in a non-invasive manner. My fiance was diagnosed with bipolar disorder a year and a half ago. This journey led me to be educated in biofeedback as a powerful and noninvasive therapeutic tool, capable of creating long-term positive changes in brains. I created this version of the device because the original costs anywhere from $1000 to $5000 (due to expensive overkill radiation detection equipment and crappy software) when it's only really a pulse oximeter with some extra math involved to let users control the blood-oxygen levels in their brain, and I can't afford something like that right now to help my fiance. This works wonders for people's mind-body connection, something my fiance and a lot of friends struggle with. 

I got the cost down to I think about $10-$20 per set of boards, and I have people who would buy them off me for $40-$50 with a low profile headband plus software and information kit I've been creating to go with it. I want to charge the absolute minimum and open source as much as possible in order to maximize the amount of experimentation and use of this device worldwide. I've already found a number of people who want to experiment with it, including recovering addicts and transcendental meditation teachers, my fiance and friends with diagnosed mental disorders, and musicians.  

Hemoencephalography is a simple practice that could help in education, athletics, attention and anxiety monitoring/training, PTSD and Depression therapy, and much more. My github page provides all of the documentation and references. It is for an older version of the project using an Arduino Nano, however, while my newer github page is still in development.

I know for sure my DIY build works and gives accurate measurements of pulse and blood-oxygenation changes (that the user can then control) based on several tests with several individuals, next step is using my own PCBs versus stock parts so there is no soldering required.

### TECHNICAL DETAILS

The HEG, like the EEG, gives users information about the brain. This device uses pulse-oximetry rather than electrical impulses, however, just like those pulse reading clips they put on your fingers in the hospital. It measures the changes in the levels of reflected red and infrared light through the user's skull. The sensor is separated 3cm from the light sources in a flat fashion as this allows us to cheaply read the average light field passing through a specific depth of the brain. The skull and skin are highly permeable, and the density of blood vessels in the neocortex ensures that the reading can measure bloodflow changes accurately. The goal with the exercise (called "brain pushups") is to increase the average oxygenation, marked by an increase in red light reflected over the ratio of infrared light - where more red blood = more oxygen. This change is directly associated with attention, focus, anxiety, daydreaming - or anything involving language or socializing. 

My sensor board hooks up via 5 pin molex to a combined Adafruit Huzzah32 Feather + ADS1115 w/ PGA board. This provides cheap mobile wifi, bluetooth (that I can sync with a phone app I'm working on), 2.4GHz dual-core processing (via an ESP32), Micro USB connection, and a 16 bit Analog-to-Digital Converter that is sensitive enough for our purposes. The program is then uploaded via the Arduino IDE, then it may be paired with a device or read directly through a serial port. The schematics themselves leave as much open as possible like the original Arduino schematics for experimentation. 

^ Explanation of Hemoencephalography.

^ DIY Schematics the CAM files are based off of.

^ Image of the combined Adafruit schematics. You have no idea how much trouble I went through to get this far.

### Words to PCBWay

First off, I love that you are sponsoring projects. This site is part of the future of how we'll get things done in the research and DIY world in my opinion. 

Secondly, the attached file contains two schematic and BOM pairs. I have an order open on this site in review to be ready to print my prototypes when I can either afford it or if by your grace you can help me with the initial prints. I only need to print the minimum amount of boards first to make sure my designs function as they should, then that would likely get me the sponsoring I need to order a lot more from you. 

This project is a passion project by a student making his own way and working for science and community health, and it would be mutually beneficial to the company willing to help me make it happen. I'm not doing this for myself.