Design Requirements

  1. The device must be comfortable to wear.
    • 1.1 — All materials for skin-attachment shall be adherent to ISO 10993.
      • A human should not carry more than 10% of their body weight. The NIH BMI table states that the minimum weight for a healthy adult of height 4’10” is 91 lbs; therefore, the corresponding maximum weight of the device is ~9.1 lbs.
    • 1.2 — The weight of the wearable components shall weigh ≤ 9.1 lbs.
      • ISO 10993 refers to the standard for biocompatibility.
  2. The device must continuously monitor the patient throughout their daily life.
    • 2.1 — Monitor shall remain securely adhered for at least 24 hours during routine activities of daily living (ADLs) before replacement or signal loss.
      • Continuous use allows for uninterrupted monitoring so that significant cough events and patterns are captured across a full 24-hour cycle without recharging or data loss.
    • 2.2 — The battery shall provide power to the device for 24 hours of continuous operation with all sensors, logging, and communications enabled on a single charge.
      • The device must remain adhered throughout its entire cycle (24 hours) in order to function.
  3. The device must be able to detect cough events in at-home environments.
    • 3.1 — The device shall measure chest acceleration between 2 and 30 m/s2 at a sampling rate of at least 20 Hz.
      • The acceleration of the chest during cough has been measured to be between 5 and 20 m/s2 in laboratory conditions.
    • 3.2 — The device shall measure the acceleration of the abdominal muscles at a sampling rate of at least 20 Hz.
      • The acceleration range of the abdominal muscles during cough must be determined through testing.
    • 3.3 — The device shall measure the tilt of the torso between 0-60° with an accuracy of ±5° within 0.5 sec.
      • The human torso can move forward during cough, with the angle corresponding to severity.
    • 3.4 — The audio and chest acceleration component of the device shall turn on within 0.5 s for 1 minute once the tilt and the abdominal-acceleration reaches a set threshold.
      • The sensors need to turn on within this timeframe in order to capture the data surrounding the cough event.
  4. The system must be able to store data.
    • 4.1 — The wearable component of the device shall be capable of storing signals for all sensors for a period of no less than 24 hours.
    • 4.2 — The app component of the device shall be able to store one month’s sensor output.
      • The amount of data that will be stored in the device over a period of time will be determined by the sensor selection.
    • 4.3 — The device shall sync data with the mobile application via Bluetooth with a 90% success rate within 10 seconds at regular preset intervals.
      • The amount of data transferred at one time should be transferred in this time to encourage ease of use.
  5. The device must be able to classify individual cough events by severity.
    • 5.1 — The device shall detect cough counts with at least 80% accuracy.
    • 5.2 — The device shall detect periods of rest and activity cycles with at least 80% accuracy.
      • CoughComm requires a high degree of accuracy in order to classify coughs by severity, as cough categories have very small differences from each other.
    • 5.3 — The device shall be able to measure cough audio at a frequency of 0.4 to 1.6 kHz.
    • 5.4 — The device must be able to differentiate wet from dry cough.
      • 0.4 to 1.6 kHz is a known cough frequency, and wet and dry coughs are known to possess different audio waveforms.
  6. The system must provide a user-friendly interface.
    • 6.1 — Power On and Low Battery Level indicators shall be displayed.
      • The user must be able to know that their device is on in order to use it.
    • 6.2 — The laptop simulator that interprets data shall display message relating to severity level in the English language to the user.
    • 6.3 — The laptop shall display results back to the user.
      • The user must also be able to receive the data in order to communicate with their healthcare provider about a future course of action.
    • 6.4 — The text and background colors shall possess a minimum of 3:1 contrast ratio.
      • All text and background colors must possess a minimum 3:1 contrast ratio, per the Americans with Disabilities Act. For reference, black text on a white background possesses a contrast ratio of 16:1.