Virginia Tech
A Compact Ultrasonic Airflow Sensor for Clinical Monitoring of Pediatric Tracheostomy Patients
Abstract
dc:description.abstractInfants and young children with tracheostomies need better respiratory monitors. Mucus in the tracheostomy tube presents a serious choking hazard. Current devices indirectly detect respiration, often yielding false or delayed alarms. A compact ultrasonic time-of-flight (TOF) airflow sensor capable of attaching directly to the tracheostomy tube has been developed to address this need. The ultrasonic flow sensing principle, also known as transit time ultrasound, is a robust method that correlates the timing of acoustic signals to velocity measurement. The compact prototype developed here can non-invasively measure all airflow into and out of a patient, so that breath interruption can easily be detected. This paper concerns technical design of the sensor, including the transducers, analog/digital electronics, and embedded systems hardware/software integration. Inside the sensor's flow chamber, two piezoelectric transducers sequentially transmit and receive ping-like acoustic pulses propagating upstream and downstream of flow. A microcontroller orchestrates measurement cycles, which consist of the transmission, reception, and signal processing of each acoustic pulse. The velocity and direction of airflow influence transit time of the acoustic signals. Combining TOF measurements with the known geometry of the flow chamber, average air velocity and volumetric flow rate can be calculated. These principles have all been demonstrated successfully by the prototype sensor developed in this research.
Degree
thesis:*- Name thesis:degree_name
- Master of Science
- Level thesis:degree_level
- masters
- Discipline thesis:degree_discipline
- Mechanical Engineering
- Department dc:contributor.department
- Mechanical Engineering
- Grantor dc:publisher
- Virginia Tech
- Year dc:date.issued
- 2013
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Ruscher, Thomas Hall
- Chair dc:contributor.committeechair
-
- Wicks, Alfred L.
- Committee members dc:contributor.committeemember
-
- Muelenaer, Andre A.
- Meehan, Kathleen
Subjects
dc:subject × 5Rights
dc:rights- Statement dc:rights
-
- In Copyright
- Licence dc:rights.uri
Identifiers
dc:identifier.*- Dc Identifier Other
- vt_gsexam:206
- OAI identifier oai:identifier
- oai:vtechworks.lib.vt.edu:10919/50143