[DIYbio] Re: BioPrinter won 1st Prize in Instructables Design Competition!

Congrats and very cool platform.

Though not sure why go the X-Y rectangular axis system at all, and why inkjet technology is needed as the liquid dispenser (which brings with it significant challenges, i.e. clogging, pore size, etc).  You had the working compact disc drive mechanisms with their working polar-axis control system (linear actuator for 'r', drive spindle for theta; perhaps replace the spindle motor with stepper for easy positioning without requiring an encoder wheel).  Petri dishes are already circular so would integrate well directly with the existing polar (i.e. rotational) disc drive mechanism, i.e. spin the dish and address points in the dish via sector (angle) and track (radius).  The liquid dispensing could be done by very small diameter tubing run through a peristaltic pump from a large well/beaker source which dispenses drops as needed from above, positioned via the linear actuator -- such pumps are very accurate, to uL's or nL's.  Add multiple lines from multiple pumps for dispensing multiple reagents, arrange these in a row on the radial axis.

X-Y axis as seen in typical lab robotics is needed to mimic the positioning of humans with minds trained for cartesian addresses and grasping by the shape of human hands which have thumbs.  Motors on robots do not have good thumbs, they have spinning shafts and work better with polar axis.  Which is why hard drives, compact discs, floppies, are all circular, rather than square.  When designing new machines and automating protocols, fit the protocol/equip to the new machine not based on human limitations for best results, rather than build a machine which for traditional/limiting human-style equipment.

If there are points to the contrary I'd love to hear them.


## Jonathan Cline
## jcline@ieee.org
## Mobile: +1-805-617-0223
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