NECKSPEC Range of Motion, Neck Device


This was my senior project in university, done with valuable input from the Walla Walla General hospital. It continues to be ongoing as I gather the resources to continue development. The details of the project, in rough chronological order, are below. I've also added thoughts and insights that have developed throughout the project.


My third biggest challenge in this project

Let me begin by stating that this is not the first device I considered redesigning at the hospital. I only had an idea that there may be some room for redesigning something that the physical therapists used, and I wasn't sure exactly where to start. All of my correspondence with the personnel at the hospital began with a cold call (or cold email, as it were); nothing was pre-established ahead of time.

The project was more or less completely self-led, and while I had access to the therapists for asking them questions and looking at the therapy center, I wasn't allowed to talk directly with the patients. This is understandable considering the confidentiality involved in healthcare, and I didn't want to try to jump through the hoops to make that happen in case I forgot to file a document or something, and there ended up being legal repercussions. Wouldn't have been a great way to wrap up my final year in university.

This created one of the biggest challenges to the whole project, which was that the most direct users interacting with the products (the patients) were the single party whose voice wasn't directly heard. Were I doing this again, I would have seen to it that I could speak to someone who wasn't in the field, but still using the therapy tools, though I'm not exactly sure how. Presumably, if I were doing this for a design company, the legalities would have been finalized ahead of time.

That forced me to make wider assumptions about the patients, and also forced me to consider solutions that were fairly simple in terms of patients' interactions with the product, so that I could easily analyze those interactions in a virtual environment.


Cervical goniometer: definitions and background

A cervical goniometer is a device that measures the range of motion (or angle of flexibility) of a patient's neck (cervical vertebrae). It is useful in physical therapy for anyone who has had any sort of head or neck injury, in measuring how flexibility is changing over time. It is used in three ways, around each of the three dimensional axes of the head. This is illustrated above.


Device and technology in use today, and opportunities for improvement

This is the current device used at the Walla Walla General Hospital to measure and monitor the flexibility of patients' necks. It uses a combination of magnetic compass and inclinometer with graduated markings to determine the movement of a patient's head. This compass/inclinometer is attached to a head strap using velcro for quick replacing of the gauge, to conform to the specific test being administered.

Although this is the most high tech, commonly used device that I've found, other devices use similar methods. As far as I was able to find, nearly all methods for measuring cervical range of motion relied on some sort of head mounted device with the measuring devices mounted on it.

The main problems I found with this method were as follows:

  • The device may be applied somewhat differently depending on the therapist. Should a patient move or change insurance providers, the new therapist may perform a new diagnostic which could indicate a different level of flexibility than the previous measurements. Furthermore, should a patient grow their hair out or the topology of their head changes (for instance, swelling from hitting their head), that changes the fit of the device.
  • The device is a challenge to record from. A therapist must perform the test, write it down, and later compare it to previous measurements. This increases the work a therapist must do, and forces them to spend their time doing calculations that could be better spent providing therapy to other patients.
  • The device is a bad experience for many patients. While most may not overtly object to such a thing being strapped to their head for a short amount of time, it does underscore their current condition, which in turn decreases their feelings of dignity and autonomy. They even require assistance putting it on and taking it off.

Possible alternate technological solutions

Of all the various devices capable of measuring head and neck flexibility, the overall technology broke down into four distinct fields. Their pros and cons are listed below, in order of listing:

  • Ultrasound – This method uses inaudible sound waves to create an picture of movement. It does, however, require larger equipment to use, and may require specific training.
  • Radiography (X-Ray) – This method is exceedingly accurate (what's more accurate than bone photos for understanding bone flexibility?), but it's not portable and has safety concerns when people are exposed to it too often, which is unsuitable for people who often come in.
  • Digital Sensors – This method offers accurate results, and is quick and portable; but, it also may be difficult to use and inconsistent based on the particular way it's used.
  • Motion Capture – This method is quick, and has the possibility of being portable. The only drawback is that it has a low accuracy since placing markers on soft tissues may misrepresent the movement of the joints below those tissues.

As an aside: the second biggest challenge in this project

Stepping back a bit chronologically, the second greatest challenge that I faced while completing this project was the physical therapists themselves. Don't get me wrong, they gave me much more information and were much more amiable to my project than they had any obligation to be. The challenge was that the physical therapists (and many other professionals who work in similar fields), were trained to improvise and find creative solutions for their immediate therapeutic needs. They had only experience in being critical of their tools to the point where they could evaluate the results, and create their own tools if necessary.

This is similar to most other peoples' perspectives, which isn't tuned to notice where products fall short or what technologies could be implemented, but to get over that hurdle and focus on the results. After all, the patients are the main priority, and healthcare is (at least somewhat) a selfless profession.

However, there is a principal difference. Where most other people simply try to ignore these greater possibilities for product solutions, physical therapists are trained to improvise their tools. A piece of equipment doesn't have soft enough (or large enough) hand rails? Attach foam pipe cover onto the rail, and tape it securely at the ends. A weight is too cumbersome for many patients regaining their strength? Attach a knotted rope so they can grip it at the angle they prefer. This offers the advantage that I was able to simply look around and see what they had hacked, but the disadvantage where when I asked them about it, they didn't want to speak too badly about that product since the previous version was so much worse.

Another facet that exacerbated this problem was that most of the obvious design problems had already been solved by the newest model of each product. The hospital had (at the time) not purchased another product when the current one worked just fine with a slight modification. After all, the therapists were already used to the old product that had been improved, and any new addition would mean resources spent on installation and training for the new product.


Device ideation

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I ended up selecting the digital sensor technology, for its already widespread use (smartphones, mostly) and relative simplicity. The main challenge was integrating that in a way that was beneficial to all parties involved, as well as appealing visually. It also had to be easy to use for therapists, as well as cheap. That last part was a significant part because the current solution ( weighted inclinometer & magnetic compass with straps and velcro) is relatively cheap to buy, which made that my only quantifiable parameter.

I think it's also worth noting that this was before (or toward the beginning of) the 'wearables' explosion, in conjunction with the 'internet of things' movement. Currently, there are many consumer solutions for using wearables to directly monitor facets of a person's health, and many more likely to be made available in the coming yeas. But apart from general pedometers/sleep trackers and more specialized things like heart rate monitors, in late 2011/early 2012 wasn't much on the market for directly measuring a person's health.


Another aside: the biggest challenge (where I grew the most) in this project

The biggest challenge was myself. I started sketching things that closely resembled the current solutions, just mapped from one technological solution to the other. That was helpful (something familiar would be more quickly accepted by therapists, and require minimal training), but unnecessarily limiting. My advisor, Bill Lane, helpfully alerted me to this. I needed to think (cliché notwithstanding) outside of the box, and explore more extreme possibilities. I come from an engineering background (I changed majors when I wanted to do something more creative and less monotonous), so starting from a stable and reasonable place seemed the most reasonable. But Bill always told us the old "Why can't [x] do [y]…?" or "Who's to say [a] can't be [b]…?", which has been immensely necessary for my own development. A large part of design is removing what is not necessary or useful until a suitable result is created, so beginning with unnecessary assumptions or limitations is a huge liability. Furthermore, there will always be competitors who have better skills, more resources, more up to date computers, etc.; but one of the greatest ways to stand out as a designer is to simply not unnecessarily limit yourself. At least that's been my experience.

These limitations can be created by actively making assumptions about a project or a solution, or they may be subconsciously made by our own biases and perspectives. Either way, they're things that constantly need to be minimized wherever possible.

On the other side (because only considering one side of an idea would itself be an unnecessary limitation), this is not to say we should focus exclusively on the improbable. A large part of design (as I understand it) is taking a highly conceptual idea or notion and applying it to the "real world". The rubber must, at some point, meet the road or else it falls within the purview of art (which certainly has its own merits, that I'll not attempt to discuss here). The point is to start from an open-minded viewpoint, and to work to find a valuable application that still satisfies all the project requirements.


Further ideation and choosing device details

With Bill's advice in mind, I looked at the various ways a digital sensor might interact with the head. Whatever the solution, I knew the sensor would need to be securely placed against the head in some way.

I also knew that it would need to be placed against a firm part of the head– no earrings or clipping to the lips or anything. That reduces erroneous movement that the sensor may pick up and confuse with neck flexibility. I considered some sort of mouth mounted device, since a firmly held mouthpiece would likely give accurate movement results, but ultimately decided against it due to the hygienic complications as well as how little people tend to enjoy a piece of plastic being inserted into their mouths for any amount of time.

"We're going to measure the flexibility of your neck vertebrae, now open up."

Additionally, any patients with a nonstandard dental condition (braces, dentures, significant tooth loss) wouldn't have as much accuracy without fitting the device to each person, which would require more time and resources that could be spent on more direct therapy.

I also considered a headphones type solution, but it didn't meet the criteria of being on non-movable tissues. The headphones may fit slightly differently each time. In addition, many patients may have sensitivity around the ears and/or not be comfortable with something intruding into their ear canals. Even if it is placed over the ears, it may still move and lack dependability in measurements. Akin to the oral solution, would you want a therapist sticking something into your ears in order to measure your neck? 

I finally realized that a glasses-type device would satisfy the requirements, while maintaining comfort and autonomy with patients. The frame would need to fit snugly on patients in order to not move when the tests are being administered. In addition, the frames would need to either be disposable or easily cleaned to maintain hygienic conditions, though not likely more than the current solution.

The other advantage to this is that the feel of a glasses frame is familiar to many people, especially the adults who make up a large portion of the patients needing therapy for the neck. Outside of that group, nearly everyone (in most conceivable markets for this product) has at least tried on glasses at some point and is more likely to feel comfortable wearing a glasses frame than a mouthpiece or headphones.


Hardware/software details

I wanted to get a feel for exactly how much something like this would cost for the electrical components, as well as how difficult it would be to create an initial model. I looked on for combination accelerometer/3 axis gyroscope components, as well as bluetooth transceivers (low energy, of course). These components, in addition to the other necessary circuitry, batteries, and manufacturing would carry an estimated cost between $50 and $100 per model, depending on the number of units purchased. This is further backed up with products such as the Texas Instruments SensorTag, which goes for about $25 and whose battery may be run for a long time before requiring replacement. It also contains several other sensors that aren't necessary for this project's application, which would drive the cost down. However, the device would have to be smaller than the SensorTag which would drive up price.

An application would also need to be developed for smartphones/tablets, which would add to the upfront cost to get manufacturing started. The specific software features and constraints for a device like this might act as its own project, so I won't try to anticipate the specifics here. Overall highlights might include a simple graphic to show patients their progress, and automatic record keeping and calculating of trends. And automatic cloud upload as well as social network integration.

On the battery front, consider that the Nike+iPod sensor battery typically lasts about 1000 active hours before requiring replacement (the battery is not removable), so a bluetooth low energy device that's simply feeding data to an app without any initial calculation would be comparable in lifespan. Whether the battery can be replaced, or the sensor is to be rechargeable or the battery replaceable will depend on further research into the physical therapy field itself.



I ended up going with a smaller profile design, simply so as to be as comfortable and unimposing as possible. The hardware within the bridge of the frame may need to be bigger, but this gives a good indication of the size that modern electrical components may require. Furthermore, a smaller frame may be easily disposable or stored with a patient's records in a cabinet somewhere.

In summary, this device would have distinct advantages over the current devices used to measure neck flexibility in three main ways:

  • Measurements are more standardized – The fit of the device would be the same each time the patient uses it. No varying fit due to the length of hair.
  • Measurements are more repeatable – Since the fit is the same each time (with the exception of growing children, who may be accounted for by multiple frame sizes), the results are directly comparable for a better view on the progress a patient is making.
  • A better experience for the patient (and a better possible experience for the therapist) – There is far less objection in the average person's mind to wearing a glasses frame than to wearing a more complex head strap or a mouthpiece or headphones. That creates a more pleasurable experience (or at least less painful), and maintains more dignity and autonomy for the patient.

But we're not done yet.


Where this project is currently

I'm working on creating a workable prototype using some inexpensive sunglasses and the aforementioned Texas Instruments SensorTag (pictured above, ready for making an epoxy putty base that securely attaches to the sensor). After considering how to attach the device (which is fairly large compared to the possible size of the finished device), I decided on using epoxy putty. This would allow me to make a sort of mold around the device (protected by masking tape) that fuses to the plastic of the glasses frames. This would also let me sand it with a high resolution for stable device mounting. I used marine-use epoxy that's safe for use in potable water tanks, so as to increase product safety despite the fact that I'm going to paint over the whole thing anyway.

So far, I've set the epoxy putty on the glasses and I need to sand it for a uniform look. I wasn't able to get exactly the effect I wanted because I had to use rubber gloves for safety, but a few more times working with the epoxy putty should work that out. I also didn't account for how much to use and overshot that a bit, so the glasses are somewhat heavier than I would have liked, but I can remove a bit of the epoxy to lighten them.