Heart Monitoring R&D Testing Device

For this project, I worked on a prototype wearable sensing device designed to interface with a disposable patch. The prototype patches were costly and limited in availability, making them impractical for frequent R&D testing and iteration. My role was to design and develop a low-cost, reusable testing patch to support internal mechanical, electrical, and wear testing without consuming the expensive prototype patches. In parallel, I investigated and resolved electrical contact issues in defective prototype patches, restoring their usability for testing and providing insights that informed subsequent design iterations of the wearable system.

Project Overview:
-Designed and iterated a wearable ECG patch prototype intended for low-cost data collection
-Emphasized user experience, wearability, and reliable electrode contact
-Conducted mechanical wear testing, electrical validation, and material exploration
-Developed multiple prototype generations informed by testing outcomes and observed failure modes

Key Engineering Contributions:
-Designed and fabricated multiple wearable testing patches to evaluate form factor, electrode placement, and mechanical stability
-Iteratively redesigned patch housings, electrode docks, and attachment features based on wear-test feedback
-Developed low-cost testing methods to validate ECG signal collection using prototype hardware
-Identified and addressed failure modes related to stiffness, buckling, electrode adhesion, and contact reliability
-Balanced usability, manufacturability, and electrical performance under tight cost constraints

Prototyping & Iteration Highlights:
-Early Proof of Concept: Created FDM-printed proof-of-concept patches to demonstrate feasibility to stakeholders
-Explored snap-fit electrode housings, patch geometry, and dock attachment strategies
-Conducted early design-space exploration to assess user interaction and assembly concepts
-Developed a rough PCB concept to evaluate electrical connection strategies

Wear Testing & Mechanical Refinement:
-Iterated prototypes to a state suitable for mechanical wear testing
-Conducted multiple 12hr wear tests to evaluate comfort, adhesion, and robustness during everyday motion
-Identified patch buckling during arm movement and stiffness-related comfort issues
-Added protrusions for user handling, hooks for wire routing, and under-dock wire paths
-Reduced dock size to improve comfort and free usable surface area

Material & Layout Redesign
-Transitioned from rigid plastic to compliant foam materials to improve wearability
-Prototyped and evaluated multiple foam types for compliance and durability
-Redesigned electrode layouts into linear configurations to accommodate different electrode types

Electrical Contact & Testing:
-Designed and fabricated a spring-contact height testing tool using adjustable hardware
-Identified optimal spring compression range (approximately 0.3–0.65 mm) for reliable contact
-Used screw pitch and parametric CAD variables to iterate contact height efficiently
-Verified electrical continuity between electrodes and contacts using multimeter testing
-Measured contact protrusion and electrode extension using a Keyence microscope

Defective Patch Investigation & Shim Solution:
-Identified inconsistent electrical contact in a subset of prototype testing patches
-Traced failure mode to insufficient contact height between interface and electrodes
-Designed and implemented a thin conductive shim to improve contact reliability

Data Collection & Results:
-Successfully collected ECG data using a low-cost prototype patch (~$20)
-Reduced complete test failures from 3/14 to 0/10 while using shim with defective patches
-Demonstrated that targeted mechanical and electrical changes significantly improved data reliability

Skills & Tools
-Wearable device design and prototyping
-Iterative mechanical design driven by real-world testing
-FDM 3D printing for functional prototypes
-Electrical contact design and validation
-Failure analysis and design trade-off evaluation
-Data collection and basic analysis
-SolidWorks parametric and assembly modeling
-Python (basic data handling)
-Keyence microscope metrology