Introducing the NeuroStimDuino! Developed by Neuralaxy - https://www.neuralgalaxy.com/ - this device offers a super affordable (if you compare it to the devices used in labs) way to control the frequency, strength, pulse width, and duration of electrical stimulations with a microcontroller! Their device and software is all open source too! https://github.com/neuralaxy/NeuroStimDuino 

The device also came from the same site that the little sensors came from - https://www.crowdsupply.com/