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.

D-Lab Design Reviews

Monicor Production Plan

1. Who will use your product?
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.

Temperature-Sensitive Prototyping

We tested out autoclave tape as a cheap means of sensing overheated circuit parts today. Shown here are two examples of autoclave tape subjected to heat from a soldering iron.

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.

Looks-Like Prototype

next steps: - get EKG to output signal and use laser cutter to create puzzle piece design

Monicor Work Plan

As we approach the end of the term, our D-Lab EKG team has developed a work plan to structure our remaining time. We hope to achieve each of these milestones for the dates listed to keep on track. Before heading out for the summer, we want a functioning device that we will be able to show our community partners in Nicaragua.

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

Eureka! We can use autoclave tape!

Why haven't we realized it before?? The paint indicator we have been looking for could be some lower-temperature version of 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.

Predicate Device Assignment

I began my search by looking for EKGs, but the trail that I ended up on was actually a line of heart monitors. The "family tree" of heart monitors is very large with many, many, branches, but it seems like there are several that form the core and that were inspiration for later models:

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

To better understand how electrocardiographs are brought to market, we researched the Premarket Notification or 510(k) for various devices. The 510(k) notification indicates that a device is "substantially equivalent" to a prior technology. Companies seeking approval must prove the similarity between their new creation and a past creation. This is a necessary process regulated by the U.S. Food and Drug Administration (FDA). By going through the summary reports of the 510(k)'s, we are able to trace a technological ancestry from a modern device to a more foundational device.

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.

Predicate Device Exercise

A device that I found on the FDA website that is similar to ours is the Medick MHM200 Personal Heart Monitor. The device falls under the classification name: Electrocardiograph, Ambulatory, with Analysis Algorithm (Product Code: MLO). I traced this device back through its predicate devices and here's what I found:

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!

Here are the results:

2009: K091513- Smart ECG (SE) Series Electrocardiograph

2001: K014108- MAC 5000 ECG Analysis System

1999: K991735- MAC 5000 Rest ECG Analysis System

1982: K820885- Marquette Option II ECG Analysis Computer for MAC 1 Electrocardiograph

This was a good example of a 510(k) for multiple devices at once because the Shenzhen company submitted this for four of their models at once!

The image above is of the ECG- 1230 model. The image to the right is of the ECG- 1210 model.

Why do we deserve a Patent?

There are a number of EKGs out on the market today. Here are images of just a few (click to enlarge the images):

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

Schematic Diagram of Simple Circuit (requires a computer for signal processing):

Schematic Diagram of Complex Circuit (performs all necessary functions):

We have decided to build the more complex circuit, as it provides more opportunities for modularity.

2nd Weekly Status Update

1) What we planned to get done this week.
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!

Leads!

What a progress-filled week! We now have a clear vision and timeline of goals that need to be accomplished.

In addition to building the circuit this week, we'll be working on building a prototype of the leads that will be used for patients. The lead will consist of two components: a permanent structure connected by wire to the circuit in the machine and a semi-disposable attachment that will be attached to patients' arms using tape. The contact between the two pieces will be made with small metal connectors. Right now we're experimenting with sewing snaps and coke bottles, which have the perfect dimensions and material for this purpose. We'll be working this week on designing a casing for the permanent part of the contact using SolidWorks. We'll share whatever we come up with soon!

Weekly Status Update

1) What we planned to get done this week.

This week we wanted to put together a plan for the rest of the semester that would enable us to produce a working EKG that would be useful for a clinic in Nicaragua. Specifically, we wanted a timeline of achievable benchmarks, a detailed list of materials that we would need to order, and a short video demonstrating the function of the technology we are trying to build.

2) What we actually got done this week.

We were able to achieve all of our goals for this week by meeting during class, in D-Lab's room in E34 over the weekend, and constantly communicating electronically via email and online collaboration tools. Our demo video has been written, filmed, and posted on our blog. We put together a basic representation of what we want our ultimate project to look like and short script depicting a real world scenario where it might be used. We have researched several potential EKG designs and collected a parts list that will allow us to get started on building a functioning EKG. Our list includes quantities, prices, model numbers, and links to retailers that will sell these parts to our team. Finally, we have put together a timeline that we will use to guide our progress through the remainder of the semester. We were careful to make sure that we had achievable benchmarks at every step so that tangible goals could be met.

3) What we plan to get done this week.

This week, we would like to get started on our first functioning prototype of the EKG machine. Once our parts have come in, we'll start out with the basics to understand the core concepts behind such a device. For our first design, we will need to build a circuit, leads, and interface with computer software to produce a digital signal of the heart. Throughout this whole week, we will be continuing our research into innovative designs that build off the principles we have been taught in D-Lab Health.

Prototype 1 Video!

Here is the much awaited video of our first prototype!



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

Prototype 1

Working on prototype 1!

We are using a simple cardboard box at this stage to represent the 'body' of the EKG. Our current plan for our initial EKG is to have 3 leads/electrodes created from aluminum cans.

We will be creating a video discussing our first prototype more in detail within the week. Stay tuned!

- D-Lab EKG Team

Road Map Meeting

Talked with our parter in Nicaragua, Dr. Norori, and he is eager as we are to make this project a success. Thanks to Mureji for her Spanish skills!

Hola Mureji....
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

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!

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