Ballistocardiogram (BCG) Data-Acquisition PCB

A ballistocardiogram, abbreviated BCG, records the subtle motion of the body associated with cardiac contraction and the ejection and movement of blood. Unlike an electrocardiogram, which measures the heart’s electrical activity, ballistocardiography focuses on a mechanical response.

These motions are small, so the acquisition electronics must handle low-level sensor signals while preserving useful physiological information. That requirement makes board layout, grounding, power, component selection, signal integrity, and repeatable validation central engineering concerns.

This project focused on the data-acquisition hardware used in a university research platform. The PCB work supports signal capture and experimentation; it is not presented here as a medical device or diagnostic product.

As an undergraduate research assistant at Texas State University, I helped relaunch and improve a faculty-developed ballistocardiogram data-acquisition platform. My work covered the complete board-level engineering loop rather than ending when the PCB layout was complete.

• Designed and simulated custom mixed-signal printed circuit boards.
• Supported PCB assembly and first-power-on hardware bring-up.
• Measured and evaluated signals with oscilloscopes and logic analyzers.
• Troubleshot board-level functional and signal-integrity issues.
• Created the project bill of materials (BOM) to organize component selection, quantities, sourcing, and cost information.
• Improved component sourcing, manufacturability, cost, and deployment scalability.
• Transferred design information, test data, and lessons learned to the next group of research students to support the project’s long-term continuity.

The available board designs show the evolution of the acquisition electronics, component placement, connectors, test points, and mechanical outline. Three-dimensional PCB renders were used to review layout and integration before fabrication and assembly. KiCad was used for schematic capture, PCB layout, and three-dimensional board review throughout the design process.

Hardware bring-up used staged checks so that power, references, interfaces, and signal paths could be evaluated before complete system operation. A Digilent Analog Discovery 3 provided oscilloscope and logic-analyzer measurements, giving direct evidence of circuit behavior and helping isolate board-level faults.

The results informed subsequent revisions and practical improvements to component availability, cost, manufacturability, and deployment. This work connected schematic and layout decisions with measured performance on physical hardware.

I also created the project bill of materials to organize component and sourcing information. To help the research continue beyond my involvement, I shared the accumulated design information, test data, and troubleshooting knowledge with the next group of research students.