A Multifunctional, Embedded-based, Bluetooth-enabled, Programmable, Biphasic-waveform Stimulator with Real-time Neural Signal Acquisition

Summary

Here, we describe a new device specifically designed for preclinical deep brain stimulation (DBS) research along with a neural signal recording unit. This device provides extensive flexibility in waveform parameters, including shape, frequency, pulse width, and amplitude, and the recording of neural spikes and local field potentials.

Abstract

The study introduces a lightweight, Bluetooth-enabled deep brain stimulation (DBS) device that is designed specifically for preclinical research in small, freely moving animals. To address the current limitations in waveform flexibility and wireless control, we developed a compact, multifunctional stimulator capable of delivering programmable, charge-balanced biphasic waveforms while simultaneously acquiring neural signals. The system integrates off-the-shelf components for current regulation, signal amplification, and analog-to-digital conversion, all managed by a low-power microcontroller. The assembly includes key steps such as circuit integration on a double-sided 30 x 30 mm PCB, waveform programming via nRF Connect, and validation through saline and load resistance testing. In vitro assessments demonstrated reliable current output across varying load impedances, effective saline operation without waveform degradation, and high-fidelity neural signal recording with a signal-to-noise ratio exceeding 35 dB. These results confirm the device's suitability for closed-loop neuromodulation experiments and lay the groundwork for future translational studies in DBS therapy.

Introduction

This work introduces a novel deep brain stimulator to explore changes at the molecular and behavioral levels in experimental animals. Although various micro-stimulator devices have been discussed in the literature, they vary significantly in size, weight, stimulation capabilities, ability to deliver prolonged stimulation, and the requirement for external power sources. Most rodent devices rely on external power, which limits their utility in studies requiring simultaneous stimulation and behavioral observation¹. While some solutions, such as tethers, magnetic waves, or light sources, attempt to address this issue, each comes with its own set of....

Protocol

System architecture
In Figure 1, a low-power microcontroller acts as the core of the system, controlling waveform generation, signal processing, and the protocol of communication. The amplitudes of the waveforms are controlled by the programmable current source used. The system uses an integrated H-Bridge circuit for alternating the current direction, and thus creates the biphasic waveforms required to stimulate neural activity. A microcontroller-aided digital resistor, in combination with a shunt resistor, enables programmable waveform modifications through an I2C interface protocol. To ensure that the current pass....

Results

The device underwent different verification and evaluation tests, and the product was tested for its feasibility in five stages: Output waveform evaluation, current output test, saline test, voltage drop test, and recording test.

Output waveform evaluation
The primary test of the device was to check the shape and mode of the waveform using a 1 kΩ resistor connected across the device. It has successfully delivered a biphasic waveform with interphase delay in a digital stora.......

Discussion

This multifunctional miniature device marks a meaningful step forward in the design of integrated systems for both neural stimulation and signal acquisition. Unlike existing platforms such as those described by Angotzi et al.⁵ and Melo-Thomas et al.⁸, which emphasize either multichannel recording or stimulation, our system uniquely combines programmable, current-controlled biphasic stimulation with real-time neural signal recording in a compact, wireless form factor. T.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
CP2102 USB	Silicon labs		provides a complete plug and play interface solution that includes royalty-free drivers
DMHC30025LSD H-Bridge circuit	DIODES		This new generation complementary MOSFET H-Bridge features low on-resistance achievable with low gate drive.
microcontroller MDBT42/STM32G491CCU6	STMicroelectronics		ARM Microcontrollers - MCU Mainstream Arm Cortex-M4+ MCU 170 MHz with 256 kbytes of Flash memory
Nordic BLE module MDBT42Q	Raytac Corporation		Allow communication of wirelessly transmitted data through BLE communication
OPA322 operational amplifier	TEXAS INSTRUMENTS		Single, 5.5 V, 20 MHz, zero-cross low-noise (6nV/√Hz) RRIO operational amplifier
Tina Ti Software	TEXAS INSTRUMENTS		Simulates frequency response
TLV1117 15 V, 800 mA, Adjustable and Fixed Linear Voltage Regulator	TEXAS INSTRUMENTS		It is a linear voltage that provides up to 800mA of output current with a supported input voltage range from 2.7 V to 15 V.