Telemedicine Applications of Strip

One of the things that we liked about the strip we created is its application for telemedicine. Although it was very valuable for us to create a reader for our strips, initially we were thinking of going along the lines of having a cell phone take a picture of our strips in order to read them. Once the patient, or nurse, takes an image of our strip using a cell phone, they can send it to an off-site computer, which would analyze it for average color intensity, and send back a resulting glucose level- this would be based on experiments done previously. This process is illustrated below.


Some of the benefits of this process are:
1. The ability for a health care provider to go to poorer, and more remote areas, and use a cell phone to take images of diagnostic tests and send them back to a central facility expands the number of patients that can be reached.
2. The results for the glucose concentrations are stored in a database, and can be accessed by doctors as necesary.

We thought of some of the problems that may arise and posible solutions for them:
1. Changing ambient light- This could be solved by having a color gradient on the strip itselt, which would allow the color that eventually shows up to be matched to a color on the gradient by the computer, and so be calibrated.
2. Changing camera position- This could be solved by having a barcode on the strips that would allow the orientation of the image to be recognized by the computer- this technology does exist.

In the end, we like that our test strips will eventually be able to be used in a variety of situations, whether with the reader that we are developing, or with a cell phone, and computer application. The reader is a good solution for us to pursue first because it is cheap (camera cell phones are not so cheap), portable, easy to use, and can be used in areas with no cell phone reception (this actualy was one of the problems we learnt about in Nicaragua). There is a greater possibility of all patients having a glucose reader, but not of everyone having a camera phone. The reader was also designed with local production in mind, and that is another benefit for the local people.

Further Testing of Strips

After we had concluded that we could indeed achieve a color change by adding a concentrated glucose solution, with the concentrations of reagents that we had chosen, and by applying them in layers onto filter paper, we did some tests to learn more about the sensitivity and limitations of this method. 

Firstly, we created glucose solutions of 100 mg/dL and 150 mg/dL, and this was in order to test actual blood glucose levels on our strip. 100 mg/dL and 150 mg/dL are the concentrations glucose should lie between if the test was done at a random time interval (i.e., not after fasting for 8 hours, like some blood tests are done). When we applied these glucose concentrations to our strips, we saw a color change for the 150mg/dL, but a significant lack of change for the 100mg/dL solution. This was interesting, because it meant that our reagent concentration choices were quite good, and our strip was sensitive to tell the different atleast between the limits of real blood glucose levels. 

Secondly, we tested the order in which reagents should be applied to the filter paper. We had three reagents to apply, the dye (D0), Horseradish Peroxidase (P0) and Glucose Oxidase (G0), and we alternated the order of each. From the image, you can see that we found that the best order was the one listed above, and the one that we had initially used for our tests, dye followed by the peroxidase followed by the glucose oxidase. 

Medical Device Compass Chart

Colorimetric test strips were used for measuring glucose levels about 20 or 30 years ago, but then the technology was phased out in favor of the current glucometers, that use electrochemical reactions to measure glucose levels. The main problem with colorimetric strips was that there was no accurate way to read them and translate the color to a specific glucose level. The electrochemical reactions were able to be measured more accurately. It was because of this that the development of technology for measuring glucose concentration in the developed world was diagonal as shown on the chart.

What our goal was to create a way to read colorimetric strips accurately, so that we could develop a better way to measure blood glucose that was as effective as the current glucometers, but was a lot cheaper i.e., develop upwards on the compass instead of diagonally.

At the moment we are about halfway to our eventual goal, since our device is cheap, but needs to be more accurate before it can measure blood glucose to a similiar degree of accuracy and effectiveness as current glucometers.

Elevator pitch at the MIT Museum

So all of the D-lab teams presented a one-minute pitch about their project at the MIT Museum last Saturday. This is what I said about Glucotank:

“Diabetes is a disease in which the body cannot effectively regulate blood glucose levels. Thus, patients with diabetes have glucose levels which can fluctuate dramatically in a few hours. These patients could fall into low blood glucose levels, which can cause a coma, or high blood glucose levels, which can cause long term complications like kidney or even heart failure. Patients in developed countries typically measure their glucose levels four to five times a day which a glucose machine, also known as a glucometer. They drop a finger prick of blood onto a test strip, which the glucometer then reads to measure glucose levels. By measuring their own blood glucose levels, these patients can act quickly and correct for swings in their glucose concentrations – such as by eating sugary foods or taking an insulin pill. However, current glucometers are not appropriate for patients in developing countries. Test strips are expensive and proprietary, and poor supply distribution in developing countries prevents patients from easily getting compatible test strips and glucometers. This is a problem, because each year 6 million people develop diabetes, and 80% of these new cases of diabetes will appear in developing countries several years from now. We have developed an open-source platform for reading blood glucose levels, which can be locally manufactured and sold at a significantly lower cost than existing glucometers. Our test strips change in color intensity depending on the concentration of glucose, and our reader measures the color intensity to determine the approximate glucose concentration range. Thank you and be sure to check out our poster to learn more!”

Initial Prototype Video Comments (Part 2 of 2)

Three more comments about the initial prototype videos were made. I’ll summarize them below.

The third reviewer mentioned the possibility of using urine strips. The problem (I believe) with this approach is that glucose is normally not found in urine. Glucose transporters in the kidneys reabsorb almost all of the glucose filtered, so unless there is a lot of glucose in the filtrate such that not all of it can be reabsorbed, glucose will not appear in urine tests. Diabetics who have high blood glucose levels will have kidneys that excrete excess glucose, which can then be detected in urine. However, we want to be able to measure glucose concentrations at all levels. Also, I’m not sure how representative glucose concentration in urine is of glucose concentration in the blood.

The reviewer also challenged the idea of using a cell phone, making the point that not everyone has a cell phone. A question that I have in response is whether it would be simpler to provide a cell phone to the user, given that they are rather cheap, and also the point that the patient could benefit from a having a cell phone.

The reviewer also questioned the need for having software to read the results, or to send the measurement off to a doctor. I would respond that the software will be able to more accurately compare the reading to the standardized gradient, and that if the glucose concentration appears to be out of normal, the doctor can be notified (and the doctor can then read the data accumulated over time).

Lastly, this reviewer questioned the use of cell phones as a diagnostic tool. The reviewer proposed having a health worker come to the patient instead and read his/her glucose level. The health worker would then use the cell phone to transmit data. I would respond that the power of this technology comes from using what patients may already have (cell phone) and combining it with a need (reading blood glucose levels). Ideally, patients would want to read their glucose levels multiple times a day, so having a health worker visit them routinely might not be possible. Also, it might not be a bad idea to let the data collection and storage happen instantaneously after the measurements are made (so that the information does not become lost on random paper sheets). Of course, we could be wrong about our assumption that cell phones are widely available/accessible.

The fourth reviewer liked that fact that we had a multi-layered solution, which gives us flexibility in implementing this project is such a short time. The reviewer also liked the fact that we were creating a new platform for reading colorimetric assays that would eventually be open source.
The reviewer makes the neat point that we took an old technology and combined it with newer technology to create a product that can solve current problems. The reviewer also agreed with the idea of having a controlled light system and the CCD camera (since the test strip would be placed against the glass plate, and thus no outside light would reach the interior of the box). The reviewer suggested that we could build this with a cell phone light for the time being.

In addition, the reviewer suggests that we should better work out the details of the reader, and reduce the number of steps to use the reader down to 2 or 3. The reviewer also asks that we make a budget to make sure that the device will remain affordable. Surprising, this reviewer sounds a lot like our course instructor (=P).

The fifth (and last) reviewer made the great suggestion of collecting more information: How much do we currently know about the needs of diabetic patients? What challenges do they currently face? How are they meeting those challenges? We know that diabetics in developing countries certainly are not getting their blood glucose levels checked several times a day, if at all. What risks does this pose for the patient?

We should investigate the living conditions of diabetics, what access to medical care they have, what are conventional diabetes management procedures in the region.

Commenting on our video, the reviewer said that we could have used the doctor-patient scenario in the video to better explain diabetes, since the audience might not know about the basics of diabetes and why testing is important. This is a great idea. The reviewer also suggested that we make an elevator pitch (which will come shortly!)

Thanks to all of the reviewers! We certainly got some good ideas on directions that we should pursue.

Initial Prototype Video Comments (Part 1 of 2)

We’re starting to receive comments about the about the initial prototype videos we made. I’ll summarize the comments we currently have.

The first reviewer did not understand why there was a separate cell phone application and a self-contained diagnostic machine. The reviewer liked the idea of test strips, but did not see the need for the gradient, saying that the strips did not need to be most accurate.

My response: We did not make it clear that the colorimetric assay could not be precisely read by the naked eye. Having a machine to read it (by converting it into grayscale and then comparing it against a standardized gradient) is more accurate. But then, one could argue that our test strips do not need to be that accurate – having 6 boxes is enough. I would say, though, that we should not limit our initial conceptual designs to be “just approximate enough” when we know how to make it better – if we are successful, we might even be able to market our product in developed countries. So perhaps we should make different technologically advanced levels of our product for different types of consumers.

The second reviewer liked the idea of having different levels of reading, which allows for redundancy – the lowest is reading the strips with the naked eye, the middle is using the cell phone, the highest level is using the CCD camera. The reviewer also liked the idea that one could save data on cell phone or send it to a central database (for the doctor to monitor the patient’s health).

The reviewer misunderstood how we plan to calibrate the strips. We are not using the white background to calibrate the strips - instead, we are using the gradient that appears next to the test strip for calibration. The reviewer makes a good point about the fact that shadows could significantly distort the reading – perhaps we could place two standardized calibration gradients on the strip – one on either edge (left and right).

The reviewer also makes the great point that we should have some detection method that asks the user to retake the photo if some condition fails (the background is not uniform because of a shadow). Indeed, having “sanity checks” increases the reliability of our program – it ensures that the reading falls into a certain range. Perhaps our program can even return a confidence estimate. Another simple check would be to display the result to the user and wait for a confirmation response.

The reviewer questioned how we were going to exactly develop the box – the reviewer pointed to the fact that it could potentially be cheaper (in addition to being more accurate), but it might be too complex, given the limited time that we have.

Glucophone

One of our ideas is to create a glucophone – the glucometer would be attached to the cell phone. An increasing number of people in developing countries have cell phones, so we thought that it would be a neat idea to combine glucose measurement and data collection with cell phones.

The pros of such an approach are that the cell phone can be used to display, power, and store data. The data can also be sent to a central database for remote patient monitoring. The doctor could have access to this data, and thus look at long terms trends in the patient’s blood glucose concentration should problems arise.

The cons of such an approach are that such a technology is expensive to develop and is technologically challenging to build(given the few weeks we have remaining in D-Lab Health). It would also be difficult to design a component attachable to all cell phones. There is also a company already doing this: http://glucophone.net/ However, it is not clear if this company still exists. Their copyright label at the bottom of the webpage goes to 2007 only…