Ergonomics/Toy design focus


QUESTION: Hello. I am the mother of a daughter who has low muscle tone. I have an idea for a toy that I hope will help with her fine motor control. I need to design pieces for this toy that would best benefit her by strengthening her fingers and improving her fine motor skills.

I want to make a building toy where you can simply squeeze one end into a hole or shaped cavity in the other. Or, I also have thoughts of a piece having a tab on each side, and you squeeze the piece to fit the tabs into the slots on the other piece. (Sorry about the poor description.)

Can you tell me ways to make the pieces connect that would be of best benefit to her muscle tone and fine motor control? This is the first time I've tried to explain this, so please let me know if this makes sense to you.

This is a very complex question that is best answered where you can see my hands or a technical drawing. Since there is no technical drawings, the easiest method to answer you is a video which I have uploaded onto YouTube. This way you can see my hands and hopefully better understand the concepts. The video is "private" so you will need this URL to get to it. Anyone else reading this answer can also access it.
I hope this helps,
Dr. Naomi Abrams

---------- FOLLOW-UP ----------

QUESTION: Thank you for such a thorough explanation. My daughter is a teenager and has been through OT at different times during her life so far. At this point, I think she would do well with looking at things from an adult OT rather than pediatric.

I believe I want to design to work her fine pinching (the thumb and index finger or middle finger). Is this also the pincer grasp?

I would estimate in total that I'll need 3 parts to make sure the piece fit together properly. I would imagine when the characters when fully assembled would be around 6"-7" tall each. It's choosing the actual mechanism with which I'm having trouble.

Yes, thumb + index and middle is sometimes called pincer grasp.  
As for a mechanism, that really depends on the shape and method of putting this thing together. For example, just putting together a 3D model helps develop pinch accuracy and some strength because you have to push a piece into another. If you are looking specifically for strength then you want something that is either a spring/force to open (such as a clothes pin) or spring/force to close (such as a snapping force). So long as that object needs to put somewhere with precision and is too small to fit in the hand, she will end up using a pincer grasp. You talk about tabs --  something to think about is which way the tabs are oriented. The broad, flat side should be against the thumb and fingers.
If you look at "therapy peg board" online you will see that they look a bit like cartoon nails with a broad head. Because they are round the user cannot use a fine pinch easily - they have to use a 3-jaw pinch/pincer or a key pinch to get any accuracy. On the opposite side, looking at a clothespin with flat sides where you can orient the piece with just your thumb and index.
When it comes to force, the average woman should be able to pinch in a fine pinch around 8-10 lbs and pincer around 14-15 lbs. If looking at a manufactured spring it should tell you the forces needed for compression.  If I'm understanding the design correctly, it sounds like you are looking for a torsion spring (a spring that has the elongated ends) that you could stick between two tabs to require compression forces to open or close.   
I'd need a lot more information to give you any additional advice.  If you daughter has worked with an OT in the past he or she may be able to give you a reference to an adult OT in your area that you could show your design to.


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Dr. Naomi Abrams, OTR/L, CEAS


I can answer questions regarding office, healthcare, and industrial ergonomics as well as general health and safety issues. I specialize in macro-ergonomics which deals with both individual issues (such as injuries and prevention) as well as corporate/organizational prevention plans. This includes working with companies that are interested in creating company-wide safety programs, health programs, and intervention strategies. My background is in occupational therapy and I am able to answer questions regarding specific medical injuries and workers compensation. This also makes me uniquely qualified to speak on the aging workforce and modifications specific to that population. I cannot answer questions regarding OSHA regulations and legal issues. While I know some things about manufacturing, I am not an engineer and tend to refer some of those questions to others.


My company, Worksite Health & Safety Consultants, an ergonomic and occupational health consultation firm has just turned eight years old. We are located in the Washington metro area. As owner I travel around the world speaking on ergonomics, aging in the workplace, and occupational health. I have consulted in the field of occupational health and ergonomics for the last twelve years. Additionally, I am an Occupational Therapist and have specialized in the treatment of work injuries/work-related musculoskeletal disorders and modifications for return to work post-injury for the last fourteen years.

American Occupational Therapy Association Rehab Practice Owners Network Women Business Owners of Montgomery County Leadership Montgomery

Why is My Office a Pain in My...? by Dr. Abrams Ergonomics for Therapists, 3rd Edition, edited by K. Jacobs Work Special Interest Section Quarterly Montgomery County Gazette Quoted in multiple blogs and online magazines

Occupational Therapy Doctorate with a specialization in ergonomics Masters of Occupational Therapy Certified Ergonomic Assessment Specialist

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