Difference between revisions of "Team:UiOslo Norway/Hardware"

It all started with our iGEM team wanting to build a diagnostic device to deal with the problem of antibiotic misuse. After deciding we were going to work with beta lactamase enzymes in urinary tract infections, we started with our first idea; detection of changes in pH caused by hydrolysis of the beta lactam ring found in all beta-lactam antibiotics. To do this, we initially imagined to design and use an ISFET device (Ion Sensitive Field Effect Transistor), but due to poor readouts with our lab equipment we decided after a while to move away from the pH-measurements and go for an optical solution.

Figure 1. The first sketches of Prothenius - an ISFET device run by an arduino computer
along with a simple display, to detect the hydrolysis of beta lactam ring.

The optimal candidate for optical detection of beta lactamase proved to be nitrocefin, a molecule with a beta-lactam ring that does not function as an antibiotic. When beta lactamase hydrolyse its beta-lactam ring, nitrocefin turns red. This enabled us to do an optical measurement of the color change to determine the presence of bacteria resistant to beta-lactam antibiotics.

The first idea to tackle this problem of measuring colorchange was to build a spectrometer using Arduino computer and 3D printing, but due to casts, this would have been less viable to use in for example third world countries.

We therefore decided to utilize the power that recides in the mobile devices many carry around every day; the smartphone. The modern smartphones generally have very good cameras, powerful processor calculations, and it is easy to develop apps for them. To do so, we needed to design and make hardware that allowed us to interface our samples with a mobile camera, and further design software (an app) to work with this hardware.

Figure 2. The first sketches of Phonelab. The left sketch is the very first version which was
changed to the middle sketch due to some optics problems. The sketch to the right is a single cuvette test.

The purpose of this design is to create a stable way to interface samples with the app. The app collects all the information needed to read and analyse the color distribution between cuvettes, based on the contents of each tube. It then compares the results to a pre-made list containing information on what we are looking for. It would be convinient to have a login-option with an interface where you can add projects and patients, with the possiblilty to add notes. It could also be possible to allow doctors to send prescriptions for the suitable medicine. This could, for example, be done with a QR code on sms. For more information about the app, see the “Software”-section.

Figure 3. The first drafts of the app that would analyze the colors that phonelab detects.

As in any project, there were several prototypes before arriving at our final design. The assembly of the first prototype of PhoneLab was used to find design flaws and proving that the project was possible. The problems we encountered were the focusing on the cuvettes in such a way that we get the most accurate color readout, and the color difference of each diode. We decided that the next model would feature a different geometry to fix these issues.

Figure 4. The assembly of the electronics for PhoneLab prototype 1.

The dimensions and shape of the PhoneLab Optics design with 5 tubes for the nitrocefin penta well test are shown below.This design is made with an exchangeable phone adapter to fit with many different phones. A small LED is included in each slot, to ensure a homogenous and stable illumination of the samples. The LEDs run of an internally installed battery pack, and the light intensity is adjustable. As you see there is equal distance to every slot, and light from the LEDs are emitted radially through the slots where the sample is placed, towards the origin where the lence is placed.

Figure 5. The geometry of PhoneLab Optics, made for perfect 3D prints and cuvette exposure to camera.

To further improve on our device, we imagine to coat it with a hydrophobic layer that repels polar molecules, thereby ensuring it stays clean when being used. We also want this device to autoclavable without being destroyed. In this way it can be easily sterilized, when using it on bacterial samples, and it can be reused in a safe manner. The current material is PLA plastic, meaning that we would have to change the material to make it autoclavable. The cool part about this product, in addition to the box itself, is that it interfaces of biological samples to a phone and gives the userbase the ability to store, geotag, and share information in such an easy way through our software.

To summarize; through a series of prototypes, we have designed and 3D-printed a device that interfaces urine samples, or any sample one has software to and interest in analyzing, with our PhoneLab.