Aether Engineering Design Team

Transcription

1 AETHER 1 Bluetooth Stethoscope Submitted to: John Kennedy and Lal Tummala Design Co. Ltd, San Diego, CA Aether Engineering Design Team Dalal AlQufaili John Bakker Patrick Baun Aaron Bryant Zakary Dillon Luis Fang Diego Farromeque Lionel Fox Andrew Handrop Eric Swearingen Juan Rodriguez Jerahmee Purcell Sponsored By:

2 AETHER 2 Table of Contents Page 1 Abstract 3 2 Project Description Ease of use Functionality Market Expandability 4 3 System Design Functional Block Description: Hardware Functional Block Description: Software Packaging Performance Requirements 8 4 Testing and Verification Software Testing Procedures Hardware Testing Procedures 10 5 Project Management Project Plan Hardware Team (Southbound) Software Team (Northbound) Gantt Charts Milestones 20 6 Budget 22

3 AETHER 3 1 Abstract The rapid development of the Internet of Things (IOT) and devices that can connect to the internet continues to produce markets that previously never existed. One such thriving market is wireless health monitoring systems. To take full advantage of a wirelessly connected health care environment we are focused on leveraging Wind River Systems established cloud to provide the basis for an interactive diagnostic tool. Although current systems exist in which the client can interact with a physician, their platforms are not portable for the consumer. Utilizing Wind River Systems cloud, we will develop a lightweight personal stethoscope while providing the user an intuitive and highly interactive phone application with connectivity to not only their patient record, but also their physician for instant feedback of their current vitals. 2 Project Description Our Sponsor, Wind River systems, was very specific about the capabilities needed for their Bluetooth stethoscope. The design parameters provided can be broken down into three critical areas; ease of use, functionality, and the future market expandability of the device into daily hospital use. 2.1 Ease of Use: Hardware: The stethoscope will be ergonomically designed for easy handling by the consumer with no physical interaction at the device beyond holding it over your heart, due to the design inclusion of an accelerometer, l.e.d. indicators, inductive charging system and seamless application control. The accelerometer will automatically energize the system once the device exceeds a 45 degree angle from the x axis relative to the inductive charging cradle through communication via the peripheral microcontroller and the accelerometer which will provide a path for voltage delivery to the backend Bluetooth microcontroller. A bank of l.e.d.s will provide illuminated feedback at the stethoscope alerting the consumer of battery charging status, device pairing mode and while active recording is in progress. The final hardware consideration pertaining to ease of use is the design of a wireless inductive charging system, allowing for the stethoscope to simply be placed into the cradle and begin recharging after use. Software: The software will be based upon common interfaces found within industry to promote operational recognition with other platforms. Clearly organized and delineated button layout will allow for simplistic operation and data capture.

4 AETHER Functionality: Hardware: The front- end circuit hardware will provide a filtered and amplified signal to the Bluetooth at a level necessary to digitize the signal and transmit to the android application. The provided signal will be of an easily recognizable audio signature representing the heart rate. Software: The application will provide the user an option to save the recorded audio file into memory or delete. The user interface will allow the operator to access and playback the desired recorded heart sounds. In addition to the playback feature, an upload option will provide the necessary interface to transfer the data to the Axeda cloud at which point the generated waveform is displayed on the webpage. The webpage will have the ability to remind the user via the application to upload a new recording when the next assessment is scheduled. 2.3 Market Expandability: Hardware: In order to be used in a hospital environment, the stethoscope needs to be devoid of button interfaces, seems, cracks, and crevices to allow for thorough cleaning in daily hospital use. The inductive charging, lack of physical buttons and the overall case design will achieve a robust package that can be cleaned and used in the medical field. Software: As improvements to the software and new features become available, Android application software updates will be made available through the app store. Users will receive automatic notifications when new software is available.

5 AETHER 5 3 System Design: Stethoscope Block Diagram 3.1 Functional Block Description: Hardware Inductive Interface: Inductive charging system consisting of a charge receiving coil found in the stethoscope and a base station plugged into wall outlet to provide the transmitted charging signal. Battery Charger: Provides interface for conversion and charging to the battery. Buck Boost Converter: Allows for voltage level change depending on needs of system. Voltage Regulator: Regulates voltage to 3.3 V. Coulomb Counter: Interfacing with the battery charger and peripheral microcontroller, provides feedback for charging status to indicate full charge or low charge to device. Accelerometer: Sensing device to provide voltage to Bluetooth device via feedback with peripheral microcontroller. STM32 MCU: Peripheral microcontroller for communication with l.e.d.s, power on control to Bluetooth microcontroller via accelerometer feedback, and coulomb counter. L.E.D.s: Provide visual feedback at stethoscope indicating state of unit. (Charging, charged, pairing, recording). MIC/PIEZO sensor: Sensor for signal collection.

6 AETHER 6 Audio Op- Amp: Amplification stage providing enough gain (.11 V V) to be usable by the Bluetooth microcontroller. L.P.F. : Low pass fourth order Butterworth filter with F c = 1.2 khz to provide filtered signal, eliminating high frequency noise. RN52 Bluetooth MCU: Bluetooth microcontroller performs digital signal processing and transmission to paired device. 3.2 Functional Block Description: Software Software data flow Block Diagram

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8 AETHER Performance Requirements: Audio Quality: Received audio signal will be 15 db above any introduced noise and recognizable as a heartbeat at playback. Transmitting Range: Bluetooth connectivity will be maintained within a 3- meter radius from the stethoscope to the paired device. Battery Performance: Battery will be of a 250 ma, 3.7 V type and provide continuous power to the stethoscope for no less than 30 minutes. Accelerometer: Power to be provided to device upon breaking 45 degree plane relative to horizontal and de- energize circuit upon breaking the 45 degree plane relative to vertical. Charging System: Recharges battery within 1 hour at a rate of 250 ma and hour. Sampling Speed: ADC will sample at a rate of 44.1 khz Audio Recording: Phone app will record a one- minute audio sample that will be stored in the phone s memory. Commands: Application will be able to communicate with the device via a set of commands Data transmission: Phone will transmit relevant data obtained from audio file to the Axeda cloud. Webpage: Webpage will display patient information pulled from the Axeda cloud.

9 AETHER 9 4. Testing and Verification: 4.1 Software Testing Procedures Bluetooth: Bluetooth testing and Verification will be conducted inside the android app. It includes being able to receive and transmit data to the medical stethoscope via the RN- 52 Bluetooth Microchip (V3.0) and onto the microprocessor. Testing will be on platform android 4.3 (which is the most current Jellybean). To correctly work and provide results, app should correctly identify, and properly pair to the medical device and make a clean connection. Commands should properly send commands via buttons, in order to record and manage heartbeat sounds. App should also be able to send serialized data through Bluetooth and onto the microprocessor in order to control the device. This will first be done through prebuilt working apps in order to the RN- 52 module, and commercial Bluetooth devices to test and verify the app. Axeda management: This is also known as the cloud and what enables the IOT (Internet of Things). Once the app is receiving premium samples from the device, these are then sent to the cloud service. In order to test this, a prebuilt app that is designed to only send data up to the cloud upon pressing a button will be used. Verification will be concluded when we can properly send data up to the Axeda management server and is properly stowed away. Testing will include proper management of memory within the Axeda servers and app. More complicated testing will be done by having the server send commands coming from user in a pc environment to the app and to the device via Bluetooth. GUI website display: The GUI website is on the other end of the cloud. Axeda cloud will only hold and manage data for us. The website should be able to pull and push data onto the server in a very user friendly environment. In order to test this, the server should already have been populated with appropriate data. Simulation using dummy data can be pulled and managed in the website. This also includes communication both ways by sending commands like record new heartbeats to website, then to the app, and finally to the device. Verification will include ease of use, as this is an important feature in the medical community. AE APP: Application testing and verification will be done with data from website and with data from the Bluetooth device. AE app should be able to handle incoming data from Bluetooth, manage and display data within app GUI, and send and receive data to the Axeda cloud. Since extensive testing will be included within the other parts, a main test within the application is managing data and user experience. Tests will be done with preloaded sounds that have to be decoded and analyzed in a visual graph that will represent the heartbeat.

10 AETHER Hardware Testing Procedures Amplifier: For the amplifier design we will test this by constructing the amplifier circuit and passing a signal through which we can then measure using an oscilloscope. Comparing an input signal from a function generator/sensor to the output signal from the amplifier will provide the overall gain for the circuit. The exact amount of gain that will be used in the final circuit design will determine the sensor that is chosen and the amount of gain that is needed to best compliment that sensor. Low Pass Filter: To test the low pass filter we will assemble it and then use a function generator to pass a signal into the circuit. An oscilloscope will be used to measure the resultant signal from the filter and as the function generator frequency increases we should notice attenuation around our designed cut- off frequency. We confirm our desired cut- off frequency and the resulting - 3db point and record these results. The final filter design will have a cutoff frequency of 1200Hz (+/- 120 Hz) Front End Analog Signal: Once the amplifier and filter have both been evaluated the combined circuit will be tested by injecting a signal via the signal generator. The signal generator will be set to 200 mv p- p and sweeping from 10 Hz to 2 khz. The circuit will be considered validated when a V signal is displayed with a cut- off frequency of 1200Hz (+/- 120 Hz). Sensors and Mechanical Interface: Sensor testing will involve assembling circuits based on sensor requirements for operation. With sensor circuits assembled, we will test by utilizing numerous mechanical apparatuses that best fit the sensor type and an oscilloscope to measure the resulting output. We will be basing our pass/fail criteria on whether we can attain a noticeable heart beat signature on the oscilloscope. Assuming that we have several sensors that meet this requirement, we will then evaluate which sensor to use based on the best quality signal that can be generated from the sensors and the mechanical housing in which we place them. With that said, the mechanical housings will be tested simultaneously and the housing and sensor pair that generates the best quality signal will be chosen.

11 AETHER 11 Battery and Charge Management: The battery charging circuit will be evaluated by building the required circuit and ensuring that the battery does indeed charge. Indicator LED s will be included in the design which will provide a visual feedback to the charging status. A voltmeter and an ammeter will be utilized to measure the current and voltage outputs to ensure the circuit is behaving within tolerances. Our tolerances will be such that the current flow into the battery will not exceed a 1C charge rate and our voltage level during peak charging will not exceed 4.2 volts. Our choice of battery will be determined by allowed space within the stethoscope chassis. Battery capacity will most likely not exceed 1000 mah. A Coulomb counting circuit will also be incorporated in the design and will be connected to the microcontroller. Testing this part of the design will involve the coulomb counter sending data to the microcontroller and then reading this data from the microcontroller via the android device. Micro- Controller: The microcontroller will be evaluated by ensuring proper response and operation of the following controls and indicators: LED indicator lights being properly displayed Enabling the Bluetooth module to power up upon receiving a signal from mechanical or accelerometer switch Disabling Bluetooth module upon a command via serial communication from the Bluetooth module Monitoring battery state via Coulomb counter and passing information to Bluetooth module via serial communication to be displayed on Android device. Some functionality maybe added as seen necessary as the project progresses, other functionality may be re- assigned to other peripherals or eliminated as seen necessary as the project progresses. Benchmark Evaluation: The stethoscope will be evaluated against the Eko Core stethoscope recently released to the market. Our stethoscope will perform equally to the overall functionality of the application provided and the sound performance.

12 AETHER Project Management: 5.1 Project Plan The resource requirements needed to complete the project consist of a hardware and software team. 5.2 Hardware Team (Southbound): The Southbound team will be comprised of six engineers responsible for the development and evaluation of the following circuits: 5.3 Software Team (Northbound): 1. Sensor 2. Pulse shaper (Amplifier and Low Pass Filter) 3. Battery Charging and power supply 4. Peripheral microcontroller 5. Accelerometer 6. Associated PWB design and circuit manufacturing The Northbound team is comprised of five engineers responsible for the development and evaluation of the following functions: 1. Bluetooth microcontroller integration and programming 2. Application side Bluetooth communication 2. Application Graphical User Interface 3. Communication and data transmission to Axeda cloud 4. Website connectivity to Axeda Cloud

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20 AETHER Milestones Southbound Task # Date Milestone Requirements Oct Mechanical Prototype Ready For Presentation Oct Front End sensor, inductive charging, no touch power on, microcontroller operation, properly filtered and amplified signal 3D Printed Mechanical Package ready for display at presentation. Complete circuit off of breadboard, built on proto boards, fully operating Verified signal amplification to meet.11 - Amplifier meets specs with supporting Sep 2.65V requirement data capture Oct Capture Heartbeat Signal Sensor provides adequate signal Sep Functional power supply output Sep Filtered signal output Assembled Power supply provides minimum of 3.3 V Filter has - 3 db edge over within +/- 120 Hz of 1.2 khz Fc Sep Capture Amplified and Filtered Signal Verify proper operation of filtered signal and amplifier. Signal to show attenuation at Fc and amplification between.11 and 2.65 V Dec Fully Operational Finalized Circuit Fully Operational Finalized Circuit Oct Inductive Charger Functional Nov Complete Operation and Communication with application Dec Final product Completed Oct Final Circuit and Layout Bench tested inductive charging to meet battery specification Final product operation and integration. Fully operational Final Product operation and integration. Final Product packaged and operational Finalized Circuit and Layout Completed. Ready to order production level boards.

21 AETHER 21 Northbound Task # Date Milestone Requirements Oct Bluetooth completion Oct Webpage Online Oct Signal displayed on Plotter Nov Working application Nov App GUI complete Nov Application is complete The app can successfully pair and connect to device and transfer data. Webpage is online, data transmitted from app can be appropriately displayed A signal can be displayed accurately on the plotter in the application GUI. A functional phone app is up and running. App can connect to device, input audio, interpret data, and send relevant data to cloud to be displayed on webpage. Final App GUI is simplified to be user friendly. Application is user friendly and operates with minimal errors. Ready for presentation.

22 AETHER Budget: The following charts and figures provide the initial financial need and the breakdown per design metric for project completion.

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