After the Google-Science-Fair contest I’m going to take part on the hackaday prize competition 🙂
I came to the idea of my project, when I was at a doctor’s office, and the physician wanted to take a blood sample. But he had to take more than three attempts to hit my vein with the needle. So I asked myself how to find a way to find the blood vessels and strike at the first trial. And of cause I wanted to have technical way… 🙂
After some research I found out that some illnessesrequire a treatment whereby the medicine has to be injected by the patient her/hisself on a regular basis- so what if you can’t find the vein?
My project is a machine that will assist in this procedure by searching for a vein with a phototransistor (“blue” veins can be seen in infrared light quite good – that’s why the opposite, blue light, is used to force drug addicted people away – they cannot see their veins in this light). If the vein is found, it should find the middle position and then puncture it. If everythingworked out fine a message is send by mail. When the middle of the vein is defined you just have to nick in the needle.
I plan to build everything with fully developed mechanic and pieces from computing junk. I took apart a DVD drive and took the stepper motor driving the pickup. I planned to build a step motor driver with an H-bridge, but it is more pricey to do so. I therefore bought one off the shelf from Adafruit 🙂 The arduino drives the stepper of the DVD drive so that the phototransistor is moved diagonally to the arm. So the position of the vane can be definjudges by the ammount of infrared light beein reflected.
The steps will be counted and saved at which step number the minimum or the maximum can be found – there the vein should be. In a next I’ll either take a servo or I’ll disassemble a second DVD drive so the needle can be nicked into the vane.