From Prototype Failure to Functional Injection Device (MXT)

Overview

Delivered three functional prototypes under a controlled architecture and budget, replacing trial-and-error with a requirements-driven, test-validated development process. Product development flow for a field injection device: requirements → design → prototyping → field testing → prototype handoff.
A prior pneumatic metal prototype was nonfunctional, with multiple student-made 3D-printed parts exhibiting major defects; prior efforts involved expensive trial-and-error with limited progress and unclear requirements alignment.

Core Problem

Repeated trial-and-error and vendor churn without a shared definition of success (functional requirements), controlled scope, or a disciplined system architecture to manage budget, quality, and integration risk.

Solution

Define the device's functional truth (FRD) and make a set of architecture decisions that control performance, usability, and cost—then execute through scoped SOWs and validation checkpoints.

Intervention as the PM

As the PM I entered after prior prototype attempts failed to meet functional needs. We created a detailed Functional Requirements Document (FRD) defining end-to-end use cases (injection, priming, charging, maintenance, and edge cases) and aligned stakeholders on this as the operating truth. We built a budget and cashflow/NPV framing to manage development under constraints (including warranty/defect considerations). We decomposed the system into electromechanical, fluid handling, and enclosure subsystems; wrote tightly scoped Statements of Work (SOWs) for highly specialized engineers; established communication and integration protocols; and coordinated design/testing cycles to deliver three functional prototypes.

• Functional Requirements Document (FRD) agreed as source of truth
• Budget control using cashflow/NPV framing and explicit scope boundaries
• Subsystem decomposition (electromechanical, fluid handling, enclosure)
• Clear SOWs for specialist engineers with defined deliverables and budgets
• Integrated features beyond basic injection (logging/file transfer vision, battery approach, UI/menu, control logic)

Validation

Validated prototypes through practical field testing (injections into real tree stumps and live trees), drop testing, and stress/strength analysis for critical mechanical parts (handle/needle). Measured human force requirements using a test apparatus to inform design constraints. Reliability/accelerated life testing was not performed beyond prototype scope.

Sustainability was enforced through FRD-based change control, scoped SOW execution, documented decisions, disciplined integration checkpoints, and complete end-of-project accounting (balanced budgets, paid vendors, documented handoff).

Impact Metrics

budget ≈$120K

~3× Prototypes delivered

duration: 4-month