fig. 1: New Brunswick® motor adapter
An old piece of equipment often fails, and replacement parts for it are impossible to find. There are two things you can do when this happens: buy a new piece of equipment, or have somebody manufacture the part you need. That’s why we designed and 3D printed a servomotor adapter for a New Brunswick bioreactor. Given: a 3L bioreactor with a glass vessel in perfect condition and a stainless steel head plate at an exceptional price of $1000; also equipped with a servomotor, pH electrode, and stainless steel connectors. However, if you don’t have a hardware unit to communicate with the pH, dissolved oxygen sensors, cooling-heating module, and the servomotor controller — the vessel itself is quite useless. jFermi’s main profile is to design and produce bioreactors in the 50-500 mL range, but future plans call for going up to 3L. Since this bioreactor vessel will last forever — at least the head plate — it would be a pity to let it go to waste. The controller units which belong to this bioreactor vessel are outdated, so they are cumbersome to hook up with third party units. We have a controller unit which is compatible with the sensors and heating-cooling unit, so only the motor adapter needed to be made.
There is a bioreactor vessel with this old servomotor and its adapter, so our task was just to design a new servomotor adapter to fit the head plate stirrer part. This motor is not so strong: it only has 0.2 Nm torque, but can be used in most cases. Controlling it is simple— you just use a PWM (pulse width modulation) signal.
60W 24VDC 3000rpm 0.2N.m Brushed DC Servo Motor Driver kit 1000 line D=60mm JMC 60JZS0630AS+MCDC706
The bioreactor came with this old servomotor without a driver, so we purchased the above mentioned complete motor setup for a total of €100. It took one hour to 3D design the adapter and printing required an additional 10 hours. Since the adapter part does not need to be placed in an autoclave, PLA+ material was used to print it. It has done its job perfectly, and has run hundreds of hours so far.
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