Background

Toddler high chairs are the leading cause of injury by nursery products in children under 5 according to the Consumer Product Safety Commission’s most recent report. In 2021, more than 27 children visited the emergency room daily for injuries related to high chairs. That’s more than one ER visit every hour.

There are many issues surrounding high chair safety that we couldn’t address within a semester. For example, the safety standards for these products, ASTM F404-21, were voluntary until 2018. This means that any product manufactured before then is potentially hazardous. High chairs are often passed down from one generation to another, so caregivers could be using unsafe products without knowing it. While product recalls can be effective, there is no effective method of informing the general public unless the recall garners widespread media attention. This means that caregivers can also be using a recalled high chair without knowing it.

What can we do?

• 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 we couldn’t tackle these broader systemic issues directly, we decided to focus on the high chair itself. We started asking, what are the current safety hazards with existing high chairs?

Risks:

Our research showed us that since the safety standards became mandatory, high chairs are generally pretty safe. However, one area of improvement is 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

As a team, we came up with 160 unique ideas. We eventually narrowed it down to three. They all feature a rigid restraint system that is linked to the feeding tray. A rigid restraint appealed to us because it would be easier to clean with the right material. It can also be designed to be both unavoidable and safe. Our next step was to determine how to best achieve that.

Rigid restraint attached to pivoting feeding tray

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

I modeled and rendered this alpha design using SolidWorks. It features a rigid restraint system that secures the child’s torso, waist, and crotch. It is attached to a sliding tray with a locking mechanism activated by the red button. The caregiver would press and hold the button, slide the tray and restraint back, place the child into the seat, and then secure the child by sliding the tray inwards.

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 came up with the idea for a rack and pinion mechanism as a way to couple the sliding motion of the tray with the pivoting motion of the shoulder restraints. This mechanism allows for a shorter sliding motion and also 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

Physical Prototype

We prototyped the restraint system and fitted it 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 from McMaster and machined. The tray is made of a birch plywood that was planed and sanded. Though the prototype is rough, it demonstrates our idea.

Results, Takeaways, & Next Steps

While we didn’t achieve a prototype with the level of fidelity that we had hoped for, we were happy to demonstrate the functionality of our idea. Our idea successfully addresses the issue concerning safety hazards surrounding high chair restraints. Our design is very safe while also being unavoidable, easier to clean than harness safety restraints, and it can be used with one hand. A rigid restraint system has never been done before and our sponsor was happy with what we accomplished. Through our prototyping, I learned a lot about adapting to fabrication issues and the importance of planning ahead to mitigate obstacles. I also gained experience interviewing users during our research and concept development stages.

There are a few primary areas of improvement if this project was to be continued. The first is adjustability. A child grows drastically between the ages of 6 months and 2-3 years, which is typically the range in which high chairs are used. It’s pivotal for the high chair to grow with the child. We had ideas involving telescoping or interchangeable pieces, but we weren’t able to prototype them within the semester. Another major area concerns locking. The tray must be locked in place when correctly positioned, and the release feature must only be accessible to the caregiver. Once these are implemented, the restraint system must be sized down and simplified so that it doesn’t present any additional harm to the child or caregiver. From there the product can begin user testing.