Wednesday, May 11, 2011
Final Update
This week, we planned to build a final functioning prototype, print the final puzzle pieces, demonstrate the use of the temperature-sensitive paint, and wrap up with our final presentation. Depending on our progress with the circuit, we were also considering cutting printed circuit boards that were specific to our needs.
2) What we actually got done this week.
We were successfully able to get a signal from human contact using the oscilloscope and alcohol-based hand sanitizing gel. We also printed a new and improved version of the puzzle piece lay out. We started with this last week:
And ended with this as our final prototype:
The final version is a single, compact and connected unit that features aluminum contacts between the modules. It is powered by a single 9V battery, which will replace the four 1.5V batteries that were formerly connected in series. It also contains a small green LED in each electronic module that would eventually be used for self-diagnosing purposes in the case of system failure. Overall, we’re pretty excited about our progress this week!
Thursday, May 5, 2011
Exciting News on the Circuit
The circuit in its current form, color-coded to indicate how we will modularize it.
The signals shown above were generated using pennies as leads. One penny was placed on the "patient's" chest, near the heart, and the other was held in the "patient's" hand. The figure on the left shows the signal detected by the oscilloscope when the leads were not in place. The signal on the right shows the signal detected when the leads were on the chest and hand, respectively. While these results are exciting, it requires a lot of trial-and-error of lead placement. Perhaps this finicky-ness will improve once we attach our own leads and use conducting gel.
Wednesday, May 4, 2011
5/4-Abstract
Our device is a user-friendly, modular EKG device that functions via the standard input of cardiac electrical signal (using metal leads) and outputs an electrical signal that can be viewed on any device with an LCD, such as a computer monitor, oscilloscope, or potentially a mobile device.
Our device is unique because of its use of discrete (but connectable) circuit modules, each of which performs a single function and contributes to the overall function of the machine. Additional features include a temperature-sensitive indicator that informs users when any module exceeds the optimal operating temperature and a method of broadcasting the signal to a local device via bluetooth or a wireless signal.
Our project addresses a need for cardiac diagnostic tools by allowing health practitioners at all levels to record diagnostically useful information about cardiac health and to transmit that information to specialists.
Tuesday, May 3, 2011
Weekly Update
This week, we planned to build a functioning circuit and to begin building the pieces that would go into modularization (i.e. the puzzle pieces). Depending on our progress with the circuit, we were also considering cutting printed circuit boards that were specific to our needs.
2) What we actually got done this week.
We 3D-printed two puzzle pieces (see picture below) whose shape and size was based on plastic boxes that we tentatively plan to use (final design will depend on the circuit pieces). These have space to accommodate connecting wires and will eventually serve as self-sufficient circuit modules that, when connected together, will result in a functioning and whole device. We also 3D-printed a lead connector. There are improvements to be made to each of these initial prototypes, and we will need to make more depending on the final structure of the circuit, but it was helpful to have actual pieces to work with.
We’ve identified four component that are necessary for a complete and functioning circuit: an input, which could consist of the leads or a microprocessor that generates an regular EKG signal, a band-pass filter to eliminate noise below 5 Hz and above 44 Hz, and an amplifier to produce the final signal, which can then be transmitted via audio jack to a device with an LCD screen that can display the signal. We’ve decided to segment our device into 4 puzzle pieces (this may end up being 5 depending on the ease of connectivity with 4). We’re also considering isolating the op amp as its own component, given the fact that it is the most likely to stop working of all the circuit elements that we’ll be using (it’s the most sensitive to temperature).
3) What we plan to get done this week.
This week we plan to build a final, functional form of the circuit, print circuit boards for each of the pieces, and connect them using the puzzle pieces, which will allow for specific and appropriate metal contact. We also plan to wrap up our final presentation and grant application components.
Monday, May 2, 2011
Monicor Evaluation
First, our design must be modular. The complexity of the device must be compartmentalized. If we can achieve this, then our users will have a much greater degree of ownership over the technology than over comparable devices in our domain. Our end users will be able to fundamentally understand the functionality of the EKG from the ground up. Additionally, they will be able to modify the design to best fit their specific situation and repair the device should any problems occur.
This leads to the next design criterion of making problems visible. If a modular component should fail, then our end users (doctors and nurses) should be able to identify what went wrong. Either by thermochromic paint or by electrical indicators, there needs to be an unambiguous sign that shows where the problem is happening so that the proper repair can be made.
The ultimate design must also efficiently use resources and must be able to be produced fairly easily. Cost parameters should be minimized while making sure that the components of our EKG device can be manufactured in bulk.
Saturday, April 30, 2011
Building Blocks
A diagram of the puzzle piece design is above. Right now it's designed to fit a 2inX2inX3/4in box, and it allows for metal contacts to be made easily through an interlocking "snap mechanism". We should have one printed late tonight or tomorrow, so we'll see how effective it is at providing the appropriate contacts.
This is a Sketchup model of two pieces that are positioned to interlock and a SolidWorks model of a single piece.
Here is the piece that can connect a wire on the circuit to the top half of a metal sewing snap. This piece will also be 3D printed.
Friday, April 29, 2011
Wednesday, April 27, 2011
Monicor Production Plan
Our community partner in Nicaragua is the Centro de Salud Vicente Godoy. Our aim is to build an electrocardiograph machine that will have an impact on the quality of medical care in clinics like this one. We anticipate that doctors and nurses will be using our device to make cardiac diagnoses in order to determine the best treatment for their patients. Moreover, the doctors and nurses using our device will have some fundamental understanding of how each of its modular components works together. In this way, we hope to give control over the product to our end users so that they are able to troubleshoot problems should they arise and even make modifications for improvement rather than treating the EKG as a black-box technology.
2. How will you get it to them?
We will put together kits of the modular components necessary for our electrocardiograph machine. Such a kit would include the grid for snapping the pieces together as well as multiple copies of the functional pieces themselves. We would first deliver the kit to our community partner in Nicaragua at the Centro de Salud Vicente Godoy. Based on the feedback we get from this clinic, we would ship similar kits to other health care facilities also in need of EKG diagnostics.
3. How much will it cost to make (the final product)?
We anticipate that the final cost of our product will be approximately fifty dollars. The amplifier and filtration circuit components each cost about a dollar, but we would include multiple copies in our final EKG kit. The conductive leads could potentially be completely locally manufacturable near zero cost. The grid and box components are machined out of wood which would run at about ten dollars. As of now, the most expensive component is our LCD display that reads out the EKG signal in real time. We are working to reduce the expense to further reduce the overall cost of our final product.
4. Where/how will it be manufactured?
Once we move the manufacturing beyond D-Lab, we would like to give the specs to a fabrication company to produce kits in bulk. We will hopefully achieve economies of scale by producing larger numbers of kits to reduce the cost of our product. The assembly of the EKG from modular components to a grid of functional components will happen at the point of care.
5. How will local community members be involved?
We want our device to enable community members to take full control over the technology that they are using. They would be responsible for assembling the EKG, modifying, and repairing as necessary. Once a few community members have been taught how to use our kits, they would be the ones to teach the next group of doctors and nurses about our technology. Ideally, we would like to be the catalysts, but the real reaction will take place in the hands of those with a personal stake.
Tuesday, April 26, 2011
Temperature-Sensitive Prototyping
On the right is a piece of tape that had the soldering iron run over the entire tape to show that the only part that changed color on the tape is the temperature-activated stripes. (We were worried the color might be coming form the tape burning or from residual solder left on the iron.
On the left is the aftermath of our playing around with the soldering iron and autoclave tape.
This is a good example of how heat-sensitive materials would be useful in indicating overheated or blown out circuit components, as a soldering iron essentially uses its circuitry (in this case, a high-resistance circuit) to generate high temperatures.
In the context of our project, such heat-sensitive material would indicate when a circuit component has too much power running through it. We are still looking into safe ways to test this idea on actual circuit components, as someone (Stephan) pointed out to us that blowing batteries and resistors might not be ideal for our project or for our safety.
In regards to our search for temperature-sensitive materials, we are still in the process of finding affordable (and attainable) materials. Will keep you posted.
Monday, April 25, 2011
Monicor Work Plan
4/27: budget | Specifying funding for milestones |
4/27: Leads | Build leads that are locally manufacturable with high signal/noise |
4/27: EKG Output | Get signal properly output from amplification/filter |
4/28: Oscilloscope | Read signal on oscilloscope |
4/29: Digital | Read signal using audio filtration |
4/30: Modularize | Divide the circuit into modular components |
5/2: evaluation | See if it is achieving desired outcomes |
5/2: Short indicator | Find paint/tape indicator of shorted out circuit components |
5/3: Test short indicator | Stress test circuit components until threshold heat flips indicator |
5/4: abstract | Explain value of your invention to society |
5/4: Boxes | Laser cut / 3D print boxes for modular components, or buy boxes |
5/5: Grid | Laser cut / 3D grid for placing modular components |
5/6: Grant application | Commercialize the concept post-prototype |
5/7: final presentation | Present work to D-Lab community |
5/8: Recording | Develop audio/flash memory to store EKG signal as a modular component |
5/8: Broadcasting | Develop Bluetooth/wifi capability to broadcast EKG to connected devices as a modular component |
5/11: final presentation | Present work to class |
Sunday, April 24, 2011
Eureka! We can use autoclave tape!
Autoclave tape changes color permanently to indicate whether it has been exposed to specific high temperatures and pressures that are essential to the sterilization processes of medical and scientific equipment. This is typically ~8 min at 121 degrees C (3M Autoclave Tape).
While initial google-ing shows that circuit components will stop working efficiently at ~85 degrees C, which is significantly lower than the temperature-sensing threshold of autoclave tape, we have yet to determine what temperature circuit components will reach when they blow out. If, after some initial testing, we find that these blown-out circuit components do reach temperatures exceeding 121 degrees C, autoclave tape could be a very cheap solution to our temperature-sensing predicament ($5-10 for 60 yards).
In the event that we need to detect temperatures closer to 85 degrees C, however, the following products are easy and still-cheap alternatives:
Encapsulated Indicator Labels ($31.20/100 labels)
Tempilink Sterilization Process Indicating Ink
Temperature-Indicating Liquid ($16/2 oz. bottle)
Preliminary tests will be done using autoclave tape and (possibly) color-changing nailpolish.
Friday, April 22, 2011
Predicate Device Assignment
K092853 3 Channel Digital Ambulatory Ecg Recorder (2010)
K072558 Cardionet arrhythmia detector (2007)
K063222 Detector and alarm, arrhythmia (2006)
K052240 Cardionet Ambulatory ECG monitor (2005)
KO12241 CardioNet Ambulatory ECG Monitor (2001)
K982803 Cardiac TeleCom Heart Link II ECG Arrythmia Detector and Alarm System (1998)
K934913 HeartLink I (1993)
Amazingly, there was quite a bit of interplay between detectors, alarms, and monitors (some devices were a combination of two or more of those).
EKG Predicate Devices
2010: Electrocardiograph, Edan Instruments Inc. [510(k) Summary]
-2002: MAC 5000 ECG Analysis System, GE Medical Systems IT [510(k) Summary]
--1999: MAC Series Electrocardiographs, GE Medical Systems IT [510(k) Summary]
---1982: Marquette Option II ECG Analysis, Marquette Electronics Inc. [510(k) Summary]
For a device with over a century of history, we are not surprised to find a long predicate device ancestry for the electrocardiograph.
Thursday, April 21, 2011
Predicate Device Exercise
2007: Medick MHM200 Personal Heart Monitor, Medick Healthcare Ltd. (K063339)
2001: C. Net 2100, Cardionetics Ltd. (K010396)
2000: R. Test Evolution, Novacor (K993788)
1992: King of Hearts Express (E.X.) Monitor, Instromedix, Inc. (K920984)
The last one did not have a summary posted online, so I was not able to find any additional predicate devices.
Something that I learned from this assignment was that individuals seeking 510(k) clearance don't always use the Proprietary Name of their predicate devices as listed in the 510(k) "summaries." In addition, the Novacor R. Test Evolution's summary cited the wrong 510(k) number for the King of Hearts Express Monitor (K880620 instead of K920984). 510(k) #K880620 is a chemical assay for thryoxine, which is something entirely different from an ECG!
The devices that I found on the FDA website were the products from the Shenzhen Biocare Electronics Co. LTD ECG 1210/ ECG- 1230/ ECG- 3010/ ECG- 6010 which were recently approved in 2/2011. In tracing its predicate devices I found that the original device was first approved in 1982!
Wednesday, April 20, 2011
Why do we deserve a Patent?
What our device offers that none of these do is the ability to access and make changes to the EKG circuit in the event of product failure. In addition, we are toying with several additional features, one of which is temperature-sensitive paint that can warn of a circuit blow out. Both of these aspects make our EKG more practical for use in low-resource settings, and we believe that this fact makes us a good candidate for a patent. Many of the patents that have been given on the US Patent website are adjustments to similar models of the standard EKG (similar to those shown above). We are trying to approach design of this device from a totally different angle.
EKG circuit diagrams
Tuesday, April 19, 2011
2nd Weekly Status Update
Last week, our goal was to begin construction of the simple EKG circuit as the basis for our first EKG prototype (see schematic diagram of circuit). We also planned to begin gathering materials for and experimenting with various configurations for the leads.
2) What we actually got done this week.
We ordered the required parts and had several preliminary discussions about our ideas for the form factor of the machine. However, we ran into a bit of an obstacle-we realized that the simplicity of the circuity made modularity difficult and almost inefficient. We decided that in the interest of meeting our goal of modularizing the circuit, it would be a better idea to eliminate the computer processing from the system and build a more complex circuit that performed all of the necessary functions, including data acquisition, signal amplification, noise elimination, and display (we also found and experimented with an oscilloscope, which performs this last function in a small device). Our thinking is that this will give us the opportunity to divide the entire circuit into functional components, each of which will be separable from the rest in the case of malfunction. We came up with several ideas for how to modularize the circuit in practice...the leading idea at this point is a puzzle like layout-we will use the laser cutter to create several printed circuit board pieces that each have a unique shape based on the desired function of the piece. These will all be connected into a functioning whole and fastened to a unifying base using either screws or sewing snaps (which will also be used for our leads). We will expand on these design ideas during the week to come.
3) What we plan to get done this week.
This week, we plan to start building a functional circuit in as well as begin prototyping the ideas that we brainstormed to modularize the circuit. We will continue researching possible materials that can be used as thermo-chromal indicators of an overheated part in the circuit. In addition, we will continue prototyping leads that can have snap-on disposable metal electrodes.
Update
Over the past several days, we've been working as a team to develop a new definition of modularity. At the end of last week, we had a in mind a system (see sketch) that consisted of a central module, almost in the shape of an iPod, that contained the signal-gathering circuit and allowed for easy human interaction with the circuit through an ejecting drawer mechanism. This unit would have leads coming off of it (almost like headphones) and would connect to an external monitor via an audio jack. this would allow for fast and easy transfer of the signal to a computer, which would use a specific program to eliminate noise and convert the data received into a graphical signal. However, we realized after a conversation with Jose that using this setup limits the potential for modularity within the circuit (since we would be using a simplified version of the circuit that only performs the task of capturing the electrical signal of the leads. Our task at this point is to revise our plans for which circuits we will build and how we will connect them. We are leaning towards something that integrates an interlocking mechanism that allows the multiple circuit parts to be united into one and separated if the need arises. Hopefully we'll have a new design to post soon!
Tuesday, April 12, 2011
Leads!
Weekly Status Update
Prototype 1 Video!
Main components include:
- Leads are fashioned from aluminum soda cans
- Circuit will be simple and modular
- Machine can be battery- or crank-powered
- Electrodes are color-coded to indicate placement on chest
- Machine can be connected to computer via audio jack
- Heart signals can be viewed on the computer
Monday, April 11, 2011
Prototype 1
Sunday, April 10, 2011
Road Map Meeting
Hola Mureji....Working in E34 (D-Lab Cambridge, USA) to come up with a road map for the rest of the term. Great ideas are brewing and we're excited to get a functional prototype working in the next couple of weeks. Can't wait to see the heart electrically for the first time!
me encantaria participar en el proyecto y con mucho gusto les colaboro en lo que digan, es mas es un proyecto interesante e imnovador y va a tener exito tanto para
ustedes como a los pacientes, como herramienta para salvar una vida..
cualquier cosa me contactan por correo o por celular.
Oscar Danilo Norori M.D.
Nueva Segovia, Nicaragua
Friday, April 8, 2011
Pugh Charts
Design Criteria | Weight | Datum: 12-lead ECG, Boston Hospital | 3-lead ECG, cellphone micro-controller, tab electrodes | Upload to laptop/email, tab electrodes | Replaceable Arduino boards, snap circuitry | Custom circuit amplifier, coin leads, paint indicator |
Safety | 2 | 0 | 0 | 0 | 0 | 0 |
Reliability | 1.5 | 0 | 0 | 0 | - | - |
Portability | 1 | 0 | ++ | + | ++ | ++ |
Maintenance | 1.5 | 0 | + | + | ++ | ++ |
Local Manufacturing | 1.5 | 0 | + | + | + | ++ |
Usability | 1.5 | 0 | + | 0 | + | + |
Modularity | 1.5 | 0 | 0 | 0 | ++ | + |
Total | 0 | 6.5 | 4 | 11 | 11 | |
Design Criteria | Weight | Rechargeable batteries, snap circuitry, paint indicator | Crank-powered, Upload to cell phone, paint indicator | Shake-powered, coke bottle cap leads, upload to cell phone | Crank-powered, laptop/email, snap circuitry, paint indicator | Rechargeable, laptop/email, snap circuitry, paint indicator |
Safety | 2 | 0 | 0 | 0 | 0 | 0 |
Reliability | 1.5 | 0 | - | - | 0 | 0 |
Portability | 1 | + | ++ | ++ | ++ | + |
Maintenance | 1.5 | ++ | + | 0 | ++ | ++ |
Local Manufacturing | 1.5 | + | + | ++ | + | + |
Usability | 1.5 | + | + | + | + | ++ |
Modularity | 1.5 | + | 0 | 0 | + | + |
Total | 8.5 | 5 | 5 | 9.5 | 10 |