Design VI

HW #4

2/27/2012

Joongil Chung

Jeffery Depinto

Purpose

The group’s intended project is a device that will electrically and accurately measure human limbs so as to diagnose/observe the human body especially with conditions such as lymphedema.

Section 2

Research for my portion of the report was done on lymphedema itself, how it affects humans, how it is currently measured and diagnosed, and how it is currently treated. It is vital to have this knowledge if we intend to create a device that will mainly be used to detect complications of lymphedema. In addition to lymphedema, other possible uses of the device will be explored and researched.

Section 3

Lymphedema is a condition which bodily fluid is retained and tissue becomes swollen as an effect of an irritated lymphatic system. These swollen tissues are at risk of infection, and place a certain level of urgency to detecting the complications early on. Lymphedema can be acquired in many ways such as inheritance at birth, lymphatic injury, and most notably after cancer treatment. The most common lymphedema sufferers are breast cancer patients, but it is important to know that any radiation treatment can compromise the lymphatic system and cause lymphedema. This being said, both men and women can experience the effects of this awful condition through other ways such as injury, lymph node diseases, and even parasitic infection.

Lymphedema is separated into two categories, primary and secondary. Primary is lymphedema that is developed at birth or over the course of one’s life. As of yet, there is no known cause of primary lymphedema, but many surmise that it is due to undeveloped or missing lymph nodes. Secondary lymphedema is such that affects both men and women. In women, it is most prevalent in the upper arms after surgery for breast cancer, and will be the main focus of our project. In other cases, lymphedema can affect other limbs such as the neck and legs.

The main area of concern and piece for measurement is the patient’s limb which is expanding. Currently, key symptoms to begin checking for lymphedema are patient complaints of heavy arms and difficulty fitting clothes and jewelry. Once these symptoms are observed, doctors begin their measurements of arm volume or circumference using a tape measure and compare measurements with each subsequent visit. This introduces level of error and is not as exact as a cancer patient would like them to be. As lymphedema develops further, definitive diagnosis is commonly based upon an objective measurement of difference between the affected or at-risk limb and the opposite unaffected limb as well

as comparisons to measurements of the affected limb made on previous doctor visits. At this point in time, there are no accepted criteria for a measurement difference being diagnostic of lymphedema.

A staging system has been endorsed by the American Society of Lymphology and it provides a technique which can be deployed to accurately diagnose and prescribe for lymphedema. There are four stages of lymphedema have been set forward as follows by the Fifth WHO Expert Committee on Filariasis:

Stage 0 (latent): The lymphatic vessels have sustained some damage which is not yet apparent. Transport capacity is still sufficient for the amount of lymph being removed. Lymphedema is not present.

Stage 1 (spontaneously reversible): Tissue is still at the "non- pitting" stage: when pressed by the fingertips, the tissue bounces back without any indentation. Usually upon waking in the morning, the limb or affected area is normal or almost normal in size.

Stage 2 (spontaneously irreversible): The tissue now has a spongy consistency and is considered "pitting": when pressed by the fingertips, the affected area indents and holds the indentation. Fibrosis found in Stage 2 lymphedema marks the beginning of the hardening of the limbs and increasing size.

Stage 3 (lymphostatic elephantiasis): At this stage, the swelling is irreversible and usually the limb or affected area is very large. The tissue is hard and unresponsive; some patients consider undergoing reconstructive surgery, called "debulking". This remains controversial, however, since the risks may outweigh the benefits, and the further damage done to the lymphatic system may in fact make the lymphedema worse.

It is important for our project to realize that at stage 1, the difference in sizes for the limb is less than 4 centimeters and by stage 2 the difference is between 4 and 6 centimeters. This is key to how are device will function. It will essentially be used each visit to a doctor’s office or in the comfort of one’s home at intervals of a few months to compare arm circumference. To aid in the detection of primary lymphedema gained at birth, the device will be used for all newborns with the basic symptoms and continue from then on. As for those with secondary lymphedema, the bracelet will simply replace the current form of measurement. When a difference close to 4 centimeters is detected, doctors will be alerted that lymphedema may be a possibility, and further investigation will pursue. If lymphedema is confirmed, the device will help monitor what stage of the disease the patient is at. This will help as a deciding factor for surgery. In comparison to the currently employed method of a tape measure, such a device that we are investigating will remove a significant amount of error in measurements as well as time and effort. As far as lymphedema detection is concerned, the benefits of this device are substantial.

As far as treatment goes for lymphedema, there is not much outside of surgery. A commonly employed alternative is pressure garments which are made of fabric that places a controlled amount of pressure on the affected limb. This eventually and hopefully brings down the swelling. In addition to this, exercise, bandages, and skin care are also employed methods of reducing the effects of lymphedema. If none of these work, surgery is in order

as lymphedema can eventually lead to further unwanted complications. This reason alone raises the need to detect the disease at its earliest possible state.

In addition to uses concerning lymphedema, the device can also be used as a physical training mechanism to observe muscle gain. Weight lifters and physical trainers alike use the size increase of arms as a reference to gains made during their training program. The device can be used in the same way as it is for lymphedema, that is, after every training session a measurement is taken and compared with previous measurements to see what gains have been made. Further on, this device can be used for the opposite goal as women and men alike want to lose weight and see if their limbs are decreasing in size with fat loss.

In the end, the idea of creating such a device which determines the size of limbs has many great advantages. Most importantly is its use in the medical field for detecting the effects of lymphedema. Once employed, the measurement device can begin use at birth and continue regular usage throughout a patient’s life. Great care will be taken with cancer patients as their lymphatic system becomes compromised indefinitely through radiation treatment. In addition to its medical uses, the device can also find a niche in the training field as it can be used to measure mass gain or loss as a result of a newly employed physical training program. Such an easy-to-use limb measurement device has yet to be developed, but can prove to be such an essential piece of equipment in every person’s home.

Section 4

In this next section, research was done on the basic electrical and mechanical components of the design as well as the conceptual drawings, and implementation.

The basic design would be similar to what one would consider a watch. The electronic components would be contained inside the “face” and the strap would wrap around the limb (arm). However, instead of using leather or plastic, a very low friction fabric would be used. This material that was developed by a company in the UK has a coefficient of friction close to that of ice and has the tensile strength of steel. The fabric is also non-deforming meaning it does not stretch which is key. The material that wraps around the arm needs a slick surface because it will need to stay perpendicular to the arm and not at an angle as shown below:

A measurement taken with a material that does not stay perpendicular would bring an inaccurately large and inconsistent measurement. The fabric would be wrapped inside the face and holes would be made every few millimeters to act as the measuring device for the width of the arm. To read the dots, a laser would be incorporated within the face that would be pointed to a receiver. Attached is a diagram of the laser schematic as well as the receiver. The laser would be on so long as the device was set to start. It would shine on the fabric which would not transmit any light until a hole was encountered. When the laser makes contact to the receiver, the counter would increment. Each increment would represent the distance between each hole. This would account for the width of the arm.

To account for the length down the arm, a roller would be implemented. This would be included on the underside of the face. This would be the flat part of the watch that lies on the skin. This would be the best place as it is very difficult to make a curving pattern with a component that is non-flexible. The circumference of the roller would be known and each time that it makes a full rotation (or half or quarter depending on the resolution the user prefers), a measurement of the width of the arm would be recorded. The length is now known but the information is stored only inside the device.

To display the measurement information gathered by the device, the program onboard the device would compile the information into a .txt file that includes the length along the arm and width of the arm at that spot. It would then send the file to either a computer or phone wirelessly via Bluetooth using a Bluetooth module (ADNS-7630). The file would could then be imported into excel to view the information in a graph or imported into an application on a smartphone to view. This information could then be compiled with previous measurements showing trends of expansion and compression. This information could then be shared with the user’s physician to more accurately and easily track the symptoms or to keep track of an already existing condition to make sure it is not getting worse.

Because Bluetooth is not the most reliable method of transfer, another way to send the information could be through a wireless router. A wireless antenna would be incorporated into the device that could connect to a wireless router. Then the device could send its information in this manner. However, if a home’s router was password protected, it would not be possible to connect to it without a keyboard of some kind or installation through a cord to a computer so another option would be to include a usb interface via a micro or mini usb port on the side of the face. This would make the device wired when transferring information but would guarantee proper transmission if wireless communication is not possible.

Another option that the group was deciding on was the addition to a screen to the face. A display could show what the digital reading was showing in real time so that it

would not require a computer at all. Each measurement could be taken digitally and displayed on the screen to act as a simple digital tape measure. This would be optimal for those who only want to take a few measurements and do not have access to a computer.

The basic design of the device would be simple like a watch. The face would include the electrical components such as a screen, the laser counting mechanism as well as the roller to measure distance down the arm. This simple design would also mean a low asking price so that the user would have a simple easy to use and accurate alternative to a tape measure that does not break the bank. Everyone would benefit from the users to the doctors to athletes.

Works Cited

Lawrence L Tretbar; Cheryl L. Morgan; Byung-Boong Lee; Benoit Blondeau; Simon J. Simonian (2007). Lymphedema: Diagnosis and Treatment. Springer

"Lymphatic filariasis: The disease and its control. Fifth report of the WHO Expert Committee on Filariasis". World Health Organization technical report series 821: 1–71. 1992

"Lymphedema." Wikipedia. Wikimedia Foundation, 27 Feb. 2012. Web. 27 Feb. 2012. <http://en.wikipedia.org/wiki/Lymphedema>.

"National Cancer Institute." Lymphedema. National Cancer Institute. Web. 27 Feb. 2012. <http://www.cancer.gov/cancertopics/pdq/supportivecare/lymphedema/Patient/page1>.

"Low Friction Medical Textiles for the Prophylactic Avoidance of Pressure Sores and

Prevention of Displacement of Chronic Wound Dressings Technology Collaboration

OFFER." Enterprise Europe. 27 Feb. 2012. Web. <http://www.entreprise-europe-sud-

ouest.fr/sfx/services/enquire.asp?id=12%20GB%20403U%203OA3&EnquiryType=BBS>.

This article includes the fabric with a very low coefficient of friction.

"LASER Transmitter/Receiver." Aaron's Homepage. Web. 27 Feb. 2012.

<http://www.aaroncake.net/circuits/laserxmt.asp>.

"Bluetooth Transmitter Chip." Web. 27 Feb. 2012. <http://www.globalspec.com/industrial-

directory/bluetooth_transmitter_chip>.