Acella-Help to help

We designed MonoKey to be as safe and as environmentally friendly as possible.

We designed MonoKey with the safety of the children in mind.

The survival test

We were curious whether the casing of a MonoKey would survive being rolled over by a car.
We found out that it did not just survive, it survived the whole ordeal without deformation or any scratch.
Back to top

RoHS compliant

Non RoHS-compliant electronic circuits may contain a significant amount of poisonous substances comprising:
  • Lead
  • Mercury
  • Hexavalent chromium
  • Cadmium
  • A range of flame retardants, especially:
    • Polybrominated biphenyls (PBB)
    • Polybrominated diphenyl ether (PBDE).
We use only lead-free, RoHS-compliant components ordered from reputable suppliers in MonoKey's electronic circut. We also use halide-free printed circuit boards with gold finishing (ENIG), lead-free solder to assemble the circuit, and RoHS compliant screws to assemble the casing.
Back to top

The plastic

Our first choice was one of bio-based plastics, but we found out the hard way that they are not easy to obtain.
We promptly black listed PVC because it is poisonous and largely not recycleable, and ABS because it is not transparent.
We crossed polystyrene from the list because it is brittle, poisonous, and not enviromentally friendly.
The most logical choice was polycarbonate, which is a tough, transparent engineering plastic. Unfortunately we found out that it can leach out BPA, which may cause cancer. We decided it to cross it from our list.
The other choice was acrylic (poly methyl methacrylate), but we decided not to pursue it because although it is strong (although not as strong as polycarbonate) and transparent, it can still shatter and hurt the user under some extreme condition. PET was also out of the race because it is not strong enough.

We finally decided to use polypropylene, which is shatterproof and is considered one of the most environmentally friendly petroleum based plastic (by greenpeace). We use food-grade clarified polypropylene for the protective sheet, and food-grade polypropylene colored with titanium dioxide approved in food-contact applications (for your information, titanium dioxide is frequently used to color candies).
Back to top


MonoKey measures 7.5cm X 6.8cm X 2.1cm (2.95in X 2.69in x 0.83in), too big to be swallowed by children (which virtually eliminates choking hazard), big enough to hold a number of smaller flashcards, but still small enough to pass as a flashcard. Please click the icon to view the mechanical diagram of the casing, along with its dimension.
Back to top