Minute - April


  • Met with Prof. Lima to discuss about current objectives.
  • With the help of Prof. Lima and machine shop technician, we built five cylindrical chambers with input filter holder and output quick-release insert valve.
  • We setup the pump system (All tubing and valve manifolds)
  • All parts seemed to fit perfectly.
  • Automatic arduino control system did not function properly - and on top of it, we fried an arduino chip (Oops)
  • Re-uploaded arduino code to the spare arduino.


  • Re-examined the control system to prevent any further damage.
  • We concluded that 2 Amps from the power supply may be the problem, so we decided to use different power supply (24V 0.5A)
  • Wired up automatic arduino control system and solenoid valves.
  • Confirmed that the system functions properly with the new arduino chip.
  • Tested solenoid valve functions.
  • Automatic pump operation did not work - we need to find a new relay or use transistors for 24V relay that we currently have.
  • We found out that we need to modify our code since we are using different pump now.
  • We wrote an arduino code for stepper motor control (make a complete turn forward and backward)
  • Uploaded the code and wired up the system.
  • Since our motors use 24V, we need to connect an external power to the motor shield.
  • Confirmed that the motor works.
  • Be very careful about wire configuration - wires must be connected in right order


  • Air pressure within the chamber often caused back-flow of liquid
  • Therefore we needed to have a sterile air inlet / outlet
  • Machined the cylindrical chamber rids to install an air filter
  • Installed a socket for 0.2 Micrometer in-line filter
  • Back-flow of liquid is minimized, but pump's flow rate must be reduced to 5
  • Modified the arduino code (Made each filling phase longer [55 seconds each])
  • When evacuating liquid, one chamber is always left behind due to uneven rate of evacuation through the valve manifold
  • Liquid in the last chamber does not evacuate completely due to excess air supply through other three chambers
  • The set up functions well with four chambers at most
  • Decided to use only four chambers


  • Confirmed that the relays function properly to operate pumps
  • Valve control #3 of the original board was broken
  • Needed to make a new board
  • Soldered a new control system board that incorporates valve control, pump control, and arduino on a same board


  • Started building the Drawbot
  • Found new stepper motors with greater torque


  • Conducted final testing of the pump system.
  • Decided to use bigger air filters to let more air in to prevent back flow.
  • Everything works well, done with the pump system !
  • Drawbot competition
  • Coded the Drawbot - drew HelloWorld and triangle
  • We need to make an instruction manual
  • Get ready for shipping
  • Find IV bag with 3 Outlets


  • Pump, instruction manual, and chamber system shipped!!

Link here- picture of wrapped and packed stuff. *Link to instruction manual pdf**

start/classes/principlesofdesign/allograftpreservation_2012/april_minute.txt · Last modified: 2012/04/26 17:35 by dchen
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