The project for the Bioengineering group is to create some type of device that is able to give accurate readings about ones vitals. Using devices that are currently in the market and reverse engineering the aspects that we find the most important. Not only must the device have a certain level of accuracy, but it also must be comfortable, light weight, and simple to use. After wrapping up our basic research, we have decided to focus on the measurements and sensors first. After which we begin to look into the future design and programing aspects. Right now, this is just a basic overview, and is subject to edit at any time.
To design a device that measures ones vitals and is both as light weight and comfortable(This is for the initial device). Also the device must be easy to use and accurate within 3% (2% is hoped for in the final device). Right now it is still undecided weather the device with emit a sound or a colored light if one or several of its readings are that which are deemed "unsafe". What is also undecided is how the device should be worn and any other possible extras that may be added as the project grows and matures.
Setting System Goals and Requirements
The device's primary customer is the elderly. From the survey, we gather that children and anybody who needs constant monitoring can use the device. The director of Paramedic and EMS at Howard Community College manifested an interest in a cloth that could monitor heart rate and respiratory rate to indicate signs of a heart or an asthma attack, a such device is not yet available. She also suggested to incorporate a pulse oximeter which is a device that helps detect respiratory and cardiac problems. Also, based on our survey, athletes can use this device to check their vitals before their sports activities. Our customers require that this device be portable, lightweight (no heavier than a pound), and accurate (~1% error).
Factors that set the context of requirements
Enterprise goals and capabilities
Our goal is to provide an emergency tool that will help save lives. The user or those around him/her would need to have medical knowledge to convey the right information and be instructed of the best course of action. This will increase the response time and the user will get the proper and most efficient first care he needs.
We can provide enough information and provide useful resources to design the vest.
Competitors and benchmarking information
There is no direct competitor for this device. However, there are medical instruments for personal use such as the pulse oximeter or thescanadu scout that take the pulse rate and the saturation in peripheral oxygen. There are also pacemakers: they send a shock when the heart stops or send a signal if your heart doesn't restart.
There is a company called Intelesens, Ltd, that specializes in wireless medical devices. They have developed sensors that will monitor your respiratory and ventilation system.
The device will have to be approved by the FDA. Because it is a multipurpose device, it is best to submit to the Office of Combination Products of the FDA so it gets the proper follow-up.
the Association for the Advancement of Medical Instrumentation (AAMI) is a good place to start to get the percentage of accuracy required for each feature on the device. They also have resources to help with the development and other steps of the medical device.
System goals and requirements
In compliance with medical standards, the sensors of the device should be placed at:
- The 12-lead ECG for the pulse rate as they provide a very good assumption of a heart attack. We may end up using 10 leads instead as the vest covers these.
|Electrode label (in the USA)||Electrode placement|
|RA||On the right arm, avoiding thick muscle.|
|LA||In the same location where RA was placed, but on the left arm.|
|RL||On the right leg, lateral calf muscle.|
|LL||In the same location where RL was placed, but on the left leg.|
|V1||In the fourth intercostal space (between ribs 4 and 5) just to the right of the sternum (breastbone).|
|V2||In the fourth intercostal space (between ribs 4 and 5) just to the left of the sternum.|
|V3||Between leads V2 and V4.|
|V4||In the fifth intercostal space (between ribs 5 and 6) in the mid-clavicular line.|
|V5||Horizontally even with V4, in the left anterior axillary line.|
|V6||Horizontally even with V4 and V5 in the midaxillary line.|
- The intercostal muscles to monitor the respiratory rate
Below is the ideal locations of the sensors for this project (2-leads are missing though, the yellow color shows where the sensors should be for the intercostal muscles)
- Saturation of oxygen using pulse oximetry will provide additional layer of diagnosis(insert 95% here)
Initial target goals (based on needs, opportunities and other influences)
Based on our survey, the device needs to be lightweight for athletes and the elderly. No heavier than 2-2.5 lbs. The device needs to perform at a level of low percent error, less than 2%. This is because our utmost goal is to save lives from heart attacks, asthma attacks, or exercising your body over your limit.There is an opportunity to make it stand out from the plethora of other biomedical devices; we will include a signaling system. Once the device can detect all the symptoms of a heart attack, it will light up red and emit a powerful sound, and a different color will light up if someone is getting an asthma attack. We plan on adding a temperature sensing system, which will have the abilities to sense your body temperature, and send heat waves across your body, through radiation or wiring. The temperature aspect is a bit far-fetched, and will add a bit more weight onto our device, but it's still possible to achieve. We conducted a survey, asking students at the gym, professional athletes, and the elderly questions about previous products, recommendations, and other reviews. This survey has helped us determine the primary functions of our device.
As you can see, for the elderly, they already contain a plethora of medical devices, which is why not a lot of them would need it. Weight is a factor that was highly spoken of; thus, weight needs to be low.
System performance metrics
Medical devices will be used to compare readings and the sensors will be calibrated accordingly to match the requirements below. We will use percent error to calculate the accuracy.
Defining Function, Concept and Architecture
Necessary system functions
The system will have the following functions:
- Measure your pulse rate with sensors within +/- 2%;
- Monitor your respiratory rate within +/- 5%;
- Measure your oxygen saturation using pulse oxymetry (spO2) with a 95%-accuracy;
- Emit a light or a sound to warn you when those vitals are out of range considered normal;
- Weigh less than 1.5 lbs;
- Insulation to maintain circuitry and for the user comfort.
We will measure these three main vitals:
- pulse rate/Temperature Rate
- respiratory rate
- Pulse oximetry and saturation of oxygen (SpO2)
Trade-offs among concepts
High level architectural form and structure
The decomposition of form into subsystems, assignment of functions to subsystems, and definition of interfaces
Each major vital is a subsystem.
Modeling of System and Ensuring Goals Can Be Met
Appropriate models of technical performance
Performance will be measured based on testing, and will not be modeled.
The plan of implementation and operations
Trade-offs among various goals and functions
There are two main trade-offs that conflict with the system requirements:
- With the amount of sensors we need, connected to a certain platform, the weight could easily go over 1.5 lbs.
- For testing, we need other medical devices to compare our results with them which will calculate percent error. It could be time - consuming obtaining the other medical devices.
Development Project Management
Project cost and schedule
For the e-Health sensor platform, it will cost about $100. The rest of the sensors will be around $10. Schedule depends on other students' work.
- revisit requirements for all sensors to find incompatibilities, constraints or necessary adjustments;
- reverse engineer existing devices
- come up with a design and alternatives for each vital and set up a final budget for necessary parts.
Estimation and allocation of resources
Risks and alternatives
The shield is a good development tool but it is not medical certified. Texas Instruments seems to have solutions as well. Implementing wireless might help us calibrate the sensors and use software to simplify measurements.
The next phase will be the design phase. It is recommended that students will start with the e-health V2.0 sensor platform, and use sensors made for measuring our system goals.