Neurostimulation is the application of low intensity electrical pulses to the surface of the skin for the purpose of stimulating the underlying nerves and muscles. In recent decades, neurostimulation has been used as part of a treatment called Functional Electrical Stimulation (FES) therapy to help restore mobility in the paralyzed limb muscles of stroke victims and those who have suffered spinal cord injuries. While carrying out research in areas such as pain reduction and sensory feedback, scientists have also used neurostimulation to study the effect of electrical current on neurons.

Historically, the delivery of neurostimulation has required the purchase of expensive, research-grade equipment or the expensive, time-consuming construction of custom hardware. NeuroStimDuino provides an open-source alternative in the form of an Arduino shield.

Affordable, Accessible, and Easy to Use

NeuroStimDuino was designed to help anyone with an interest in neuroscience—students, researchers, and hobbyists alike—to study the effects of neurostimulation on muscle contraction. It comes with an I²C interface through which external microcontroller boards like the Arduino Due can be used to generate different stimulation patterns and control other aspects of its operation. Each NeuroStimDuino shield has two independent output channels, which can be used to alternate the contraction of flexor and extensor muscles or to contract various muscles simultaneously. By stacking multiple shields, additional output channels can be made available.

Note: A single output channel on NeuroStimDuino is capped at 20 mA, which is sufficient to contract small muscles but insufficient to contract large ones. Large muscles can be contracted by combining the two output channels of NeuroStimDuinos in parallel.

Opens the Door to Many Different Areas of Research

NeuroStimDuino is a platform technology with many possible applications. It can be used to conduct research on how neurostimulation affects pain management and the restoration of mobility to paralyzed extremities. It can also provide sensory feedback to amputees and stimulate the transcutaneous vagus nerve to study the effects of neurostimulation on depression, arthritis, and other conditions.

WARNING: This instrument is intended for RESEARCH PURPOSES ONLY. It is not intended for human or animal use. Neuralaxy LLC does not assume responsibility for injury or damage due to the misuse of this instrument.

Features

• Generates biphasic, rectangular, and constant current stimulation pulses with programmable frequency, pulse-width, and amplitude
• Stimulation pulses are charge-balanced, consisting of a cathodic phase followed by an anodic phase of equal or unequal amplitudes (i.e. the waveform shape can be symmetrical or asymmetrical)
• Can be configured over I²C, from an external microcontroller acting as the controller
• Can be used as an Arduino shield, due to pin-compatibility with Arduino Due and MEGA boards
• Has two independent output channels per board. Multiple boards can be stacked to generate up to 222 channels.
• Onboard opto-isolators separate digital and analog signals
• Can be powered by a 9 V battery connected to a DC input or by an external 5 V input on VIN. For proper operation, we recommend two Li-Ion batteries (e.g. 18650s) connected in series. (Batteries not included.)
• Onboard LEDs visually indicate when neurostimulation is delivered, and a precision current-sense amplifier provides a voltage output proportional to the stimulation current.
• Includes several safety features such as fuses, an emergency OFF switch, and solid-state relays to shunt inputs with low impedance resistors
• Comes with a pair of 2 mm pin-style lead wires to connect with standard, reusable, hydrogel-based stimulation electrodes

Technical Specifications

• Adjustable current output range: +/- 20 mA, resolution 240 µA/step
• Adjustable stimulation frequency range: 3 – 100 Hz ¹, pulse-width 0 – 2 ms
• Maximum compliance voltage: +/- 60 V (uses +/- 72V High-voltage supply)
• The onboard 16-bit dsPIC33F Microcontroller (40 MIPS, 256 KB flash memory) operates as an I²C peripheral with a programmable, 7-bit address.
• Stimulation current output can be measured using the onboard 12-bit ADC or an external ADC.
• The PCB includes a microUSB interface but the components are not populated. (Upon request, we are happy to provide a list of the necessary components.) If populated, this interface can be used to control NeuroStimDuino from a PC by way of serial commands.

¹ Frequencies below 3 Hz and above 100 Hz are possible but require a firmware update. Please see our GitHub repository for additional details

Comparisons

Board Layout

Note: The board layout for NeuroStimDuino v1.0 can be found in our GitHub repository.

Pinout Diagram

Note: The pinout diagram for NeuroStimDuino v1.0 can be found in our GitHub repository.

Support & Documentation

For instructions and video tutorials on the placement of stimulation electrodes to evoke various muscle contractions, please refer to Electrode Placement & Functional Movement, courtesy of Dr. Lucinda Baker, Associate Professor (retired) at the University of Southern California and Axelgaard Manufacturing Co., Ltd. For NeuroStimDuino software and design files, please see our GitHub repository. If you have questions, you can use the Ask a technical question link below.