Choosing a Child-Resistant Pill Organizer Prototype
PlaySafe is developing a child-resistant pill organizer for older adults who take multiple daily medications. Three concepts were built as functional prototypes. Concept A is a snap-lid box with two latches. Concept B is a sliding tray with a push tab. Concept C is a twist-and-lock cylinder with a large grip ring. In a test with 20 adults aged 65–80 and 20 children aged 4–6, Concept A was opened by 95% of adults and 30% of children within five minutes. Concept B was opened by 90% of adults and 55% of children. Concept C was opened by 60% of adults and 5% of children. The target is to meet the applicable child-resistance standard while achieving at least 90% adult success on the first attempt. Adults in the C group reported pain in the thumb and wrist; several could not align the arrows. The team has four weeks and €8,000 left for iteration before a funding review. Write a prototype and test plan.
1. Evaluate the three concepts against the stated target. Which concept should be advanced, and what evidence supports that choice?
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Concept C is the only concept that meets the child-resistance side of the target, with 5% of children opening it versus 30% for A and 55% for B. A and B fail the safety requirement outright, so their higher adult success rates are not decision-relevant: a product that is easy for adults but accessible to children is not a child-resistant organizer. C's 60% adult success is unacceptable, but the failure is a usability problem, not a fundamental concept failure. The reported thumb and wrist pain and difficulty aligning arrows point to high torque, small grip features, and poor visual alignment cues. The next step is therefore to iterate C, not to abandon it. The evidence is limited by the small sample and the absence of a standard-compliant test protocol, so the team should not claim compliance yet. The decision should be conditional: advance C to a revised functional prototype, with A and B retained only as benchmarks.
2. Define the next prototype's fidelity, the specific design changes, and the test protocol (participants, tasks, success criteria) for the four-week window.
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Build a revised C prototype at functional fidelity using 3D-printed or machined parts with the same locking geometry and a production-like grip ring. Changes: increase the grip diameter by 8 mm, add six large ribs, reduce the required twist torque by 30% through a ramp and detent, add high-contrast arrows and a tactile click at the open position, and test two lock directions. Keep the child-resistant mechanism unchanged until adult usability is improved. Test protocol: 30 adults aged 65–85, including 10 with diagnosed hand arthritis or reduced grip strength, and 20 children aged 4–6. Each adult gets one demonstration and then three attempts to open and close; children get five minutes without demonstration. Success criteria: at least 90% of adults open on the first attempt and 100% within three attempts; no more than 10% of children open within five minutes; no reported pain above 3/10. Record torque with a gauge and video for failure analysis. Spend the €8,000 on two prototype rounds and an external test session, not on tooling.