Follow-Up Observation/Shadowing Session

On January 6th, I had the opportunity to shadow PT on two physical therapy visits with two different boys. I had already shadowed these two boys twice in September, so having a few months in between visits allowed me to really see the progress that they have made with her. These were my observations:

Child A – 14 months old; low muscle tone


At this point, Child A is now able to sit upright unsupported, which is a huge step forward from where he was just a few months ago. He can also reach for objects while sitting upright and even bang two objects together. Once in a while he gets back into a side-lying position, so PT slowly aids him as he pushes to lift back into an upright position. When he plays upright with a toy, Child A mainly uses his left hand to play while he uses his right hand to stabilize himself to stay sitting up.

A big challenge that PT is dealing with now is getting him to move onto his stomach. She shakes a small toy near him that makes subtle noises, such as a plastic maraca or a ball with a smaller ball inside. When he hears and sees it, he slowly moves towards it by reaching his arms outward while lying on his back. From his left side, Child A does not need much support to sit upright when he is lying on the floor. He has to work a lot harder reaching up from his right side.


PT holds up a plastic ring stacking toy while he is sitting upright. She has him reach towards it and pull off the rings one at a time, then has him put them each back one by one. Child A puts on and takes off each one that PT tells him to and stays sitting upright the entire time. After this activity, she puts Child A on her lap while she sits on a floor mat. She places his legs in a 90 degree position and gently keeps them in this position with his feet planted firmly on the ground. As she holds him in this position, PT uses her other hand to place toys in front of him so that he reaches forward and grasps the toys with his hands.

Seeing this progress from the first session I observed really made an impact on me. It showed me that with enough time, patience and attention, children with hypotonia can progress at a steady pace and advance physically over time.

Child B – 2 years (+ a few months) old; high muscle tone


PT holds him and tells him to carefully lean forward into a hands and knees position. He leans forward slowly so that his hands are touching the ground and she carefully lifts him back up. They proceed to do this activity multiple times so that Child B gets used to it.

After this, PT puts Child B’s orthotics on, followed by his sneakers. The orthotics give him added support in the ankle and knee areas. Having a more stable base helps keep the rest of him stable. She then places a weight around his left ankle before trying to get him to walk across the room. He walks across the room towards an iPad playing a favorite song of his while she stabilizes him and slowly guides him there. Once he reaches his goal, Child B sits down on the floor and PT adds a weight to his right ankle. With both weights on, he is aided back across the room and goes into sitting position once again when he gets to the iPad. PT does this exercise multiple times with him, going from one end of the room to the other.


PT pointed out that Child B works more with his right side during every activity. If he pushes off the ground, he always uses his right side as support since it is currently his dominant side. PT is working with him to use his left side too in order to strengthen it so that he has no dominant side and uses both of them equally. Getting rid of this current dominance will help him use both sides during activities.


PT carefully sets him into his walker. He holds on to both sides and walks without the support of PT, but uses the walker to help him. He is able to walk out a fairly long distance on his own. He does not tire easily and pushes himself to keep moving forward for a fairly long time.


Throughout this entire time he has been looking around and taking in his surroundings. As he gets tired, Child B’s legs get less stable and the bottom of his feet are no longer planted firmly on the ground. He uses the walker to hold most of his weight towards the end of his walk. Once he starts fatiguing it is difficult for him to stand up straight. PT makes sure to take short breaks while walking once he gets tired. She continues to give him encouragement and support, telling him that he is doing a great job. She also makes sure that he is holding up his weight with not only his right hand, but his left one as well.

Once again, I was grateful to be able to see theses stages of progress with my own eyes. It showed me that although it might be difficult at times, these children want to progress physically for themselves but do not know how to do so on their. The help of a PT and development tools makes an extremely noticeable difference and I am hoping that my design will have the opportunity to aid in these milestones as well.


Progress is What Matters Most

Meeting with my Advisor: PT

Although I have been jumping ahead to researching materials and textures, I had to take a step back and focus on the actual form of what I will be designing. I had a meeting with PT to review the main developmental stages I will be focusing on and to find out how to go about designing the specific curves based on the necessary physical positions.

I had already narrowed down the age range I am focusing on, which is the 6 month to 14/15 month age range. Within this time, most of the physical development that takes place includes ‘tummy time’, sitting, crawling, creeping, balancing, climbing to get on and off of things, kneeling on objects and even walking. I had some trouble differentiating crawling and creeping until PT showed me the difference. Crawling is when the child pulls himself forward on his stomach, using his hands and legs to pull his body forward. Creeping is when the child moves into a quadruped position, moving forward on both hands and knees in order to move forward.

When working with a child, PT told me that there are overall guidelines for where the child should be at developmentally. However, it really goes according to the schedule of each individual child. When asking her what stage the child should be at during each age range, she told me that there is no set answer. Instead of forcing a child to be at a specific place at a specific time, physical therapists promote stages of progress. As long as there is progress occurring, that is what matters most. Therefore, there is no set developmental timeline for children with abnormal muscle tone. There are just stages that should follow one another and my design will help further this progression.

As a physical therapist, PT says that even when a child gains a skill, one must look at the way it is done. If the physical positioning is incorrect, it will put unnecessary pressure on the child’s joints. In addition, skipping over developmental stages will effect those that follow. A good, strong and stable core is key; the more stable you are there, the more control you have away from the body.

One very important position is known as ‘crossing midline’, which is when the child transitions from their hand and knees and then back into the sitting position. The child is moving off of their center line of axis in order to rotate, which is a big struggle since children tend to get stuck in a frontal position. It is a great transitional position in the earlier developmental stages to enhance their bilateral coordination, which is when they learn to use both sides of their body equally. If there is a dominant side that the child uses, a physical therapist will encourage the use of the other side as well so the dominance is balanced out.

CrossingMidlineCrossing midline develops the child’s hip muscles, core muscles, arm strength and visual tracking. For a child to keep their head midline, to weight bear on one hand and to reach out with the other hand is incredibly difficult for them. In addition, children who are still developing physically often keep their legs straight out in front of them. It anchors them for stability since it is a very broad base that is holding them upright. Once their legs are up in a crossed position, there is less surface area for support and a large bulk of their weight is placed on their bottom.

Learning about specific positions during the developmental process helps me understand the importance of each one individually and how they transition into the next positions. It is also incredibly useful learning about them from PT since she will sit next to me and demonstrate the positions step by step. Seeing them acted out physically allows me to understand them much more than I do by just viewing images on the internet.

More Thought About Texture & Material

Multiple people have told me that it would be great to add an element to my end design that would allow parents to track the progress of their child. I have been thinking about this for a while and will continue to do so until I decide the best way to go about it. I want to keep my design as simple as possible without adding unnecessary details. Adding a technological element like this would increase the production and manufacturing cost, as well as making it too complex.

I have also been coming back to the idea of adding different sensory elements into the design, such as lights and music. However, I am determined to stick with the adage of ‘less design is more design.’ After discussing this with PT she helped me realize that the addition of these features can create a sensory overload in the child as well, especially those in my user group. Children with physical disabilities are often very sensitive to things around them. When working on their physical development, the frustration with their inability to do certain activities can be enhanced by other noises and distractions going on in their surroundings. Adding extra technological elements can create that sensory overload, causing them to be overwhelmed. Therefore, I am going to try to keep my design as minimal and useful as possible. If I decide to add additional features, I will make sure that they are completely necessary and will find the best way to incorporate them into already existing elements of the design.


PT and I were discussing this and she mentioned a product that triggered a new design idea. She said that the gertie ball is a product often used by physical therapists during sessions to enhance motor skills. Adding less air to it makes it easier for the child to grab and hold on to it, while adding more air makes it more stable so that the child can actually sit on it. What stood out to me was when she told me that there are certain gertie balls that are made with a heat-sensored material that changes colors when held. Based on the pressure that the child places on it, the color will change due to the change in heat.

Gertie Ball Colorchanging

I ordered one of these balls on Amazon in order to test it out. You can watch how it works in this video that I took:

I looked more into the technology, which I learned to be known as thermochromism, and found a US toy patent that also uses it. The patent states that the material “will change color as the temperature of the body changes.” A child is able to change the color of the toy by raising or lowering the temperature, doing so by placing it in heated or cold water or air. The heat of a child’s hands is also able to be used to change the temperature, causing a noticeable change in its color. Generally, the material goes from a darker color to a lighter one as the temperature of the material is raised.

The use of a material that changes color due to temperature might have the ability to track the physical progress in the child. The harder the child grabs onto the product the more his/her body temperature will cause the material to change color, allowing the parent to actually see the physical ability of their child progress. The more they develop physically, the greater their motor skills will advance, allowing them to grasp and hold on with greater strength over time. It can be a simple way to utilize the material to create a product that can both initiate physical development as well as track it over time.

Thermochromism also has the ability to enhance the visual and tactile sensory experience for children that will use this product. The color change will create a unique visualization that will keep them interested and since it can be changed as the child physically interacts with the product, it will teach them about cause-and-effect as well. It will intrigue them to continue engaging with the product once they see the visual effect that they are able to have on it.


I want to incorporate textures on specific areas of the product, leaving some surfaces smooth. Overall, the textures can be placed in a number of ways. They can be incorporated into areas where the child has the most physical contact with the piece for a more heightened sensory experience, one that would enhance their proprioception, or ‘awareness of one’s own body’. Another option is for the textures to be used near those areas in which the child would be in contact with the most, promoting them to reach outward towards it in order to initiate stretching and increased movement.

After a lot of research into material options, including silicone and both BPA and phthalate free synthetic rubber, I have found that material textures in children’s products come in many variations. Including textured surfaces is a very important design detail that will enhance the child’s sensory experience when using the product. It has been difficult choosing specific textures to use and exactly where to apply them. One aspect I am certain of is to use textures that vary in both size and shape to create multiple sensory experiences that can also initiate progress in fine motor skills. These are just some of the texture options that I have sketched based on research and exploration:


Placement of the textures will prove to be a key factor. After looking at other products and going through my research, I have come up with an idea of where to place the textures on the pieces. When it comes to the smaller scale textures, such as ones with small bumps or ridges, the material will be less protruding and more subtle. My idea is to place these textures in areas where the child’s whole body will be leaning against the piece, or right near those areas. They can be used for a sensory experience that will be a little more understated. Specific areas of placement can include areas that they will be lying down on top of, areas they would lean against to use as sitting support, as well as areas they would use to lay over for ‘tummy time’.

When it comes to the larger scale textures, such as ones with soft and flexible spikes, the material will protrude out more in comparison to those of smaller scale. These textures will increase the raised surface area that the child can grab or hold on to. They can be placed in areas that the child is most likely to be in contact with on their own; specifically, areas that come in contact with the child’s hands and feet. They can be implemented in areas that hang over the child so it causes them to reach up in order to feel them, as well as in areas that they would be able to lay their feet against. This would greatly increase the focused sensory experience during playtime.

Testing Size: Making a Half-Scale MDF Mock Up

At this point, I decided to push forward with my latest 3D print advancement in order to scale it up. The 3D print is only about 5 inches long, which is helpful in identifying the form but not so much the function. I wanted to see how stable the piece would be in a larger scale, as well as to see exactly how big the final product should be. This latest print has a simple curved form that varies in thickness from one end to the other. It is able to be placed in four different positions while staying upright and each position is useful for different activities. The main position it stays in allows it to subtly rock and spin since the widened base has a slight curve, which is enough to initiate movement while keeping safety in mind:


I proceeded to take the CAD file for the model into a program called 123D Make, which allows you to turn your 3D model into a two dimensional build plan. The program takes the three dimensional form you have created and slices it into layers upon your direction. I was able to choose the direction and width of the slices it would be made up of based on the material it was cut from. In addition, I hollowed out the inside so that I could fill the end piece with sand in order to test the shift in weight when placed in different positions.

In order to choose the size of the larger scale model, I researched the average measurements of a child in the age range of my user group. It turned out that the average height is about 31″, so I decided that the overall length of my first test piece would be 36″. I figured it should be a little bit larger than the child so that they can sit on it and interact with it without it being too overwhelming to them. Since the CNC has limitations due to the material choice, I had to create an 18″ half scale model. It would still allow me to test the function on a larger scale than the 3D print and pave the way for future iterations.

I chose MDF as the material to use for the model because it comes in large sheets that are easy to sand once the pieces have been assembled. After setting up the material onto the CNC, it was time to start cutting out the pieces. 123D Make works with the CNC router so the new file had to be transferred to the machine, allowing it to then follow the line paths that were programmed.

After all the pieces were cut out of the MDF sheets, the assembly process began.

I had to remove all of the unnecessary material from the interior and exterior of each part. I numbered them in size order to keep track of the way in which they would be glued together.

I was left with only the pieces required for my model and I continued to work on each one by hand. I used a hand file to clean up all of the edges to give the overall piece a smoother finish at this stage. Although somewhat time-consuming, it saved me time later on in the construction process.

During the sanding process, my thesis advisor, Professor Stan Rickel, and I discussed the best way of going about assembling the pieces. It required multiple wooden dowels to be placed through pre-drilled holes in order to keep the pieces from shifting during the gluing process.

I proceeded to widen the pre-drilled holes after all of the sanding was complete so that there would be room to apply wood glue around the dowels to keep them securely in place without falling out. I then split the parts into two piles and glued the pieces into two separate halves. This would enable me to fill the piece with sand before gluing the two halves together. I hoped that the sand would create the weight-shifting ability I wanted in the final design, however, the MDF was too heavy a material for it to really make much of a difference. I would like to test it out with a foam model, which would allow the sand to make more of a difference due to its lighter quality.

Both halves were carefully glued and clamped to ensure a close fit. I left them to dry overnight, added the sand to one half in the morning and then glued the whole piece together. I gave the piece more time to dry this time since the next step would entitle sanding down the entire surface to shape and smooth the exterior.

I clamped the entire piece securely onto a table in the industrial design studio’s sanding room. Using a hand grinder, I went over each section of the piece so that there would be a continuous surface over all of the glued pieces. I had to continuously rotate the model and re-clamp it to ensure an even surface all around. In the end, the room was completely covered in MDF dust from the excess material removed and my piece had been sanded down to the necessary form.

When the time came to finish the surface of the piece by removing all of the sanding marks, Stan happened to be in the industrial design studio with furniture designer Wendell Castle. Wendell uses a wood stacking technique similar to this in many of his pieces, so he took the time to give me advice on how to complete mine more efficiently. I carefully removed the markings from the hand grinder so that the curves would have a better flow and a smoother surface.

After the piece was completed, I began to take notes of its qualities. A thinner wall would be better, allowing there to be more hollow space inside for the sand to partially fill and allow a more noticeable shift in weight. When it came to size, this definitely help me see a more realistic scale of the final design. Even though it was just a half scale representation of what the final form would be, it allowed me to see that at full scale the piece would be too large. Instead of 36″ long, it would be sufficient for the piece to be minimized to approximately 25″ long. A smaller size will allow it to be used properly without being excessively large. In addition, no extra material will be wasted and the proportion to the child will be more in scale.