[Open_electroporator] Culture Shock, the open electroporator is a go

[John Griessen]

Thanks to Bryan Bishop I will be developing an electroporator
as in the attached proposal starting Wednesday, (and a little setting up
Q&A with suppliers today).  Here's the feature list from the proposal:

Programming will be via  USB device endpoint for serial ports, and referencing micropython documentation, plus a quick how-to 
published on kitmatic.com under the product docs section.

Power will be by 28 Volt “wall wart” external UL listed power supply.

Output zaps will be disabled when USB is plugged in – no USB remote controlling, (safety reasons).

Programmability of output zaps will be by a sequence of python commands that do not guarantee a definite pulse shape.   Pulse 
shape will have to be arrived at by trial and error, using external observations with oscilloscopes to a voltage divided down test 
point that is inherently not safe to touch, and the whole oscilloscope is not safe when using it to observe the HV discharges. 
The reason it is not safe is the voltage divider chain of resistors could fail conductive-→oscilloscope gets zapped-→people 
touching oscilloscope usually.

Micropython running on a STM32F030CCT6 which costs only $1.30 or STM32F401CBU6 which costs $2.8 will power the sequence and 
control functions.

Indicator LEDs and pushbuttons will be provided for Ready, High, Medium and Low states of the machine.  The Ready LED will be red 
or green and when red, pushing Ready button “gets it ready” for the next zap.  High, Medium and Low  pushbuttons change to 
different stored zap profiles named  High, Medium and Low.

Fire button causes a discharge.

Batt indicator LED is low duty cycle blinking red when battery needs charging soon.

Standard electroporation cuvettes with aluminum contacts will be connected somehow to the zap output such that high voltage cannot 
jump a gap to  to where the cuvette mounts when a safety guard is removed for loading and unloading cuvettes by hands.  The safety 
guard lid will probably operate like a knife switch where contacts, are more than 7mm apart and are bridged by a copper strip, (or 
pogo pins),  when the lid is pushed on.  When the lid is open, no bare contacts will have high voltage on them.  Bare metal with 
HV might be present inside a 3mm hole that a pogo pin goes into, or inside a 1.5mm insulated slot that a copper strip goes into to 
make contact.  Fingers randomly touching the cuvette area would not touch anything but insulator and have an air gap to HV of more 
than 7mm.

The overall size will be less than 10cm X 10cm X 5cm tall if using electroporation cuvettes, and smaller if using pipectrodes.
local LiFePO4 battery, circuits to charge it,  detect state of charge.

Flyback switching power supply with  flyback 57:1 transformer  to generate at least 3kV into a 30kOhm load starting from the low 
3.2V of the LiFePO4 battery, or the 28VDC external power supply.

28VDC external power supply (from AC 120V). Either/or a 28VDC external power supply (from AC 240V).

John Griessen
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