Design Review

Video Lecture

Video, Slides

Description

The design review is a 30-minute meeting intended to ensure that the team has a successful project. Students will present (using slides in tandem with their design document) and defend their design while instructors critique it, ask questions, and indentify any infeasible or unsafe aspects. Note that the instructors are not here to attack your design, but to straightforwardly inform you when you may be heading down an unsuccessful path.

Instructors and TAs will ask questions throughout and may choose the order of the blocks to be discussed. Specifically, here is what the course staff are primarily looking for:

  1. Evidence that the overall design and high-level requirements solve the problem stated.
  2. Check if the overall design has suitable difficulty for course standards and completion in one semester. Scope may need to be adjusted if otherwise.
  3. Check team members' engineering preparedness to implement each module.
  4. Check that each team member is assigned an equal portion of the project effort.

Prepare for the following sequence.

  1. Promptly project your slides or other content on projector.
  2. Introduce team members (name, major, and the project part each is in charge of).
  3. Present problem statement and proposed solution (<1 minutes) following the template in DDC (see Description 1.a)
  4. Present design overview (<5 minutes)
    1. High-level requirements: check DDC
    2. Block diagram: check DDC
    3. Physical design
  5. For the remainder of the review, you will participate in a detailed discussion of the design. Plan to cover each block, one at a time, beginning with the most critical. The course staff will ask questions and may step in to guide the discussion. Be prepared to discuss all aspects of your design with a focus on the following.
    1. Requirements & Verification: (see DDC); We'll look at all the important block requirements. Prepare to justify the components chosen and compare with important alternatives.
    2. Evidence that the design meets requirements (use the following as applicable)
      • Simulations
      • Calculations
      • Measurements
      • Schematics
      • Flowcharts
      • Mechanical drawings
      • Tolerance analysis: check DDC
      • Schedule: Suggestions:
        1. Think about what you can do in parallel, what has to be sequential;
        2. Work on hardware before software;
        3. Perform unit testing before system testing;
        4. Unit test each module on a breadboard before starting PCB design);
        5. Leave margin for unexpected delays or accidents. You are mostly responsible for those exceptions, just as if you were the owner of this senior design business;
      • Cost:hourly rate is ~$50 not $10. In addition, apply the 2.5x overhead multiplier ($125/hr is the cost of your senior design business), which includes the cost of salaries of you, your boss, CxOs, sales, janitors, etc.

Grading

The DR Grading Rubric is available to guide your DR preparation. Two sample Design Review documents are available as examples of what we expect: a Good Sample DR, a Moderate Sample DR, and a good example R&V table as it was presented in a final report. Notes are made in red type to point out what is lacking. Note that the grading rubrics and point structure may have evolved since these reports were generated, so use them only as a guide as to what we are generally expecting.

Submission and Deadlines

Your design review presentation should be ready before your Design Review. You do not need to upload this powerpoint to the course website. You will be graded on your live presentation on the day of the Design Review with the course staff.

Miniaturized Breath Sensors

Rui Cai, Yiyang Chen, Qiaozhi Huang, Yingzhuo Wang

Featured Project

## Group Member:

- Yiyang Chen[yiyangc5];

- Rui Cai[ruic2] ;

- Yinzhuo Wang[yw28];

- Qiaozhi Huang[qiaozhi2]

## Problem

Flow monitoring is crucial in many applications. We want to build a miniaturized breath sensor system that can monitor asthma.

## Solution Overview

In this wearable respiratory monitoring device, a new fluid measurement device, similar in principle to a traditional hotline, will be used to collect real-time data on a person's breathing rate. In contrast to the traditional hotline, materials such as graphene and carbon nanotubes are used as probes which is much more robust and have lower TCR(temperature coefficient of resistance). This material--graphene fiber (GF) will be welded into Wheatstone bridge and the voltage output of GF will demonstrate the velocity of air flow by controlling the temperature of the GF. Then, we will use filter to eliminate noise of the signal and do Fourier Transform to demonstrate the frequency of respiration. After that, this signal can be sent to smartphone. With previous training data online, we can analyze the signal of respiration and conclude the probability of asthma. We plan to use a mobile app to show users breathing data, summarize the data and make recommendations. We will use Bluetooth for data transmission.

## Solution Components

### Flow Sensor System

The resistance of a specific material changes at different temperatures, and the flow sensor system's control circuit measures the change in resistance to achieve constant temperature control of the sensor probe. In the thermostatically controlled fluid sensor subsystem, the heat carried by the fluid at different speeds through the sensor probe is the same as the heat provided by the compensation circuit, so that the fluid flow rate can be accurately measured. Graphene and carbon nanotubes are widely used in these sensor probes, and sensor probes using pencil and paper have recently been proposed as a new type of sensor probe. The processing of sensor probes is challenging and there are advantages and disadvantages to various methods, including soldering and metal clamping, and we are trying to design a small, low-cost and robust sensor probe.

### Circuit

The circuit of our design consists of three sections: Wheatstone Bridge, Amplifier, and Feedback control. We need to adjust the resistance of the Wheatstone Bridge to construct and balance a working space for GF sensor. As it states in previous, the flow would change the GF material’s resistance, thus create a voltage difference on both sides of the Wheatstone Bride. This difference will be amplified by the operational amplifier, and the voltage regulator will change the excitation voltage on the Wheatstone Bridge in order to keep the temperature of GF stable. The difficulty of our design come from the feedback control design. One possible way is to use transistors. In addition, if we want to eliminate the environmental temperature effect, specific temperature compensation measure should be implemented, such as add a temperature sensor in another Wheatstone Bridge. The circuit should keep the GF temperature stable and output the voltage change, this output signal will transfer to next section and be processed and analysed.

### Signal Processing and Analysis

First, we must use filter to eliminate noise of signal. As we all know, the high frequency noise can have a negative influence on the signal, which does harm to our analysis of asthma. Therefore, we must do FFT on signal we get from circuit and use high frequency filter to eliminate certain noise. Second, to calculate the probability of asthma, we must collect training data of respiration online. These data can be used to do machine learning. With those training data, the signal can be analysed easily.

### Result

Visualization Bluetooth Low Energy (BLE) features Low power consumption and faster transmission speeds. Therefore, we choose BLE to transmit data to mobile phone on this wearable respiratory monitoring device that requires long battery life and only a small amount of data transfer. We're also going to keep the interface simple and add analysis function to the app.

## Criterion of success

- Wearable and Miniaturized In the current study, wearability and miniaturization directly determine the industrialization potential of this new type of sensor. The portability of the product will help to achieve 24/7 patient health monitoring. Therefore, the development of wearable and miniaturized health monitors is considered as one of the criteria to measure the success of the product.

- Comfortable and Flexible Flexible sensors that conform to human science will significantly improve the comfort of wearing the product and determine the user's willingness to wear it. Flexibility and comfort are one of the goals of the product.

- Environment Friendly Environmental protection is becoming an increasingly important issue to be addressed today. The development of environment-friendly sensors is the goal of this research. Conventional biosensors will inevitably use environmentally hazardous materials such as plastic. this study will use degradable materials, such as paper, instead of plastic for product development.

- Low Cost Low-cost respiratory health monitors facilitate product penetration and daily use.

- Reliable and Stable As a medical product, the reliability of the product determines the safety of the life of the target object. A highly reliable and high-performance respiratory monitoring device can effectively guarantee the occurrence of accidents.

## Distribution of Work

Yiyang Chen (ME), Rui Cai (EE) and Qiaozhi Huang (ME) will be responsible for the construction of the fluid sensors, the design of the wearable device, the design and debugging of the circuitry, which are closely linked and we agree that there is no need for an overly clear distribution of work, Rui Cai will lead the development and fabrication of the circuitry. Yingzhuo Wang (ME) will be responsible for the development of the wireless Bluetooth data transmission technology, the visualization of the monitoring results and the implementation of the interactive functions.