NeuroDAC: an open-source arbitrary biosignal waveform generator

• Published in: Journal of neural engineering 2021-02, Vol.18 (1), p.16010
• Main Authors: Powell, M P, Anso, J, Gilron, R, Provenza, N R, Allawala, A B, Sliva, D D, Bijanki, K R, Oswalt, D, Adkinson, J, Pouratian, N, Sheth, S A, Goodman, W K, Jones, S R, Starr, P A, Borton, D A
• Format: Article
• Language: English
• Subjects: Algorithms; Computers; Electrophysiological Phenomena; Equipment Design; Signal Processing, Computer-Assisted
• ISSN: 1741-2560; 1741-2552
• DOI: 10.1088/1741-2552/abc7f0

Researchers are developing biomedical devices with embedded closed-loop algorithms for providing advanced adaptive therapies. As these devices become more capable and algorithms become more complex, tasked with integrating and interpreting multi-channel, multi-modal electrophysiological signals, there is a need for flexible bench-top testing and prototyping. We present a methodology for leveraging off-the-shelf audio equipment to construct a biosignal waveform generator capable of streaming pre-recorded biosignals from a host computer. By re-playing known, well-characterized, but physiologically relevant real-world biosignals into a device under test, researchers can evaluate their systems without the need for expensive experiments. An open-source design based on the proposed methodology is described and validated, the NeuroDAC. NeuroDAC allows for 8 independent channels of biosignal playback using a simple, custom designed attenuation and buffering circuit. Applications can communicate with the device over a USB interface using standard audio drivers. On-board analog amplitude adjustment is used to maximize the dynamic range for a given signal and can be independently tuned for each channel. Low noise component selection yields a no-signal noise floor of just 5.35 ± 0.063. NeuroDAC's frequency response is characterized with a high pass -3 dB rolloff at 0.57 Hz, and is capable of accurately reproducing a wide assortment of biosignals ranging from EMG, EEG, and ECG to extracellularly recorded neural activity. We also present an application example using the device to test embedded algorithms on a closed-loop neural modulation device, the Medtronic RC+S. By making the design of NeuroDAC open-source we aim to present an accessible tool for rapidly prototyping new biomedical devices and algorithms than can be easily modified based on individual testing needs.ClinicalTrials.gov Identifiers: NCT04281134, NCT03437928, NCT03582891.