Background

Toddler high chairs are the leading cause of injury by nursery products in children under 5. In 2021, about one child every hour visited the ER for high chair-related injuries.

High chair safety poses challenges beyond what we could address in a semester. For example, ASTM F404-21 standards only became mandatory in 2018, meaning older hand-me-down products may be unsafe. Even with recalls, caregivers are often unaware unless the issue receives major media attention, leaving many to unknowingly use hazardous or recalled chairs.

What can we do?

We decided to focus on the high chair itself. We asked, what are the current safety hazards with existing high chairs?

• Chair tipping over, either from poor design or from the child leaning too far or pushing off a table.

• Strangulation caused from the child slipping downwards and getting their neck caught on the feeding tray.

• Lacerations from pinch points caused by poor design, moving parts, incorrect assembly, or cracks in the chair.

• Unrestrained child falling out of chair.

Since the safety standards became mandatory, high chairs are generally pretty safe. However, our research identified one area of improvement: the safety restraint.

Key Finding

Not using the built in safety restraint exacerbates the existing hazards of high chairs.

How might we redesign the safety restraint so that it

Ideation

We came up with 160 unique ideas and narrowed them down to three. They all feature a rigid restraint system that is linked to the feeding tray. A rigid restraint system appealed to us because it would be easier to clean, more secure, and safer.

Rigid restraint attached to pivoting tray

We purchased an affordable high chair and some flexible material to experiment with different restraint shapes.

I modeled this rigid restraint system that secures the child’s torso, waist, and crotch. It is attached to a sliding tray with a locking mechanism. The caregiver would press and hold the button to release the tray, place the child into the seat, and then secure the child by sliding the tray forward.

Alpha Design

Motion Coupling

We were concerned that our sliding tray design wouldn’t provide enough space for the caregiver to comfortably place the child into the seat. We were also worried about the potential for our shoulder restraint to strike the child’s face or body as the tray was slid inwards.

Rack and Pinion Mechanism

I decided a rack and pinion mechanism could couple the sliding motion of the tray with the pivoting motion of the shoulder restraints. This creates a wider opening for the caregiver to place the child into the chair. The restraint can then be comfortably positioned over the child as the tray slides in.

Refined Model

Final Prototype

We fitted our restraint system to a purchased high chair instead of prototyping the chair itself. The rack and pinion were 3D printed. The two support plates were cut using a water jet, and the rest of the components were purchased and machined. The tray is made of birch plywood.

Results, Takeaways, & Next Steps

While we didn’t achieve the level of prototype fidelity we hoped for, we successfully demonstrated our idea’s functionality. Our design addresses safety hazards in high chair restraints with a rigid system that is safer, easier to clean, one-hand operable, and unlike anything currently on the market. Our sponsor was pleased with the outcome, and I gained valuable experience adapting to fabrication issues, planning ahead, and interviewing users during research and development.

Future improvements focus on adjustability and locking. High chairs must grow with the child from 6 months to 2–3 years, so features like telescoping or interchangeable parts are essential. The tray also needs a secure lock accessible only to caregivers. Once these elements are refined, the system should be scaled down and simplified for safety before moving into user testing.