Design, manufacture, and control of a low-cost positive airway pressure device.

Current positive airway pressure devices cost NZ$800-$2500, posing a financial barrier for the estimated 1 billion individuals worldwide with sleep apnea and those researching respiratory diseases. Increasing diagnoses and research interest in the area necessitate a low-cost, easily accessible alternative. Thus, the mePAP, a high-quality, multipurpose, low-cost (∼NZ$250) positive airway pressure device, was designed and prototyped specifically for respiratory disease research, particularly for sleep apnea. The mePAP allows user customization and provides researchers with an affordable tool for testing positive airway pressure algorithms. Unlike typical commercial devices, the mePAP offers adaptability with open-source data collection and easily modifiable software for implementing and analysing different control and diagnostic algorithms. It features three control modes: constant; bilevel; and automatic; and provides pressures from 4 to 20 cmH2O, controlled via a phone app through Wi-Fi, with a mini-sensor added at the mask for increased accuracy. Validation tests showed the mePAP's performance is comparable to a gold-standard Fisher & Paykel device, with extremely similar output pressures. The mePAP's low cost enhances accessibility and equity, allowing researchers to test ventilation algorithms for sleep apnea and other respiratory conditions, with all data openly available for analysis. Its adaptability and multiple applications increase its usability and usefulness across various research and clinical settings.

Physical Artificial Arterial Pulse System for Development and Testing of PPG-Based Sensors.

A physical system to generate a PPG-mimicking signal was designed and validated using everyday low-cost components to aid in medical sensor design. The pulse waveform was created by driving a working fluid into a silicone tube and changing the pressure within it. The corresponding waveform mimics a PPG signal through an artery, is adaptable, and repeatable. The working fluid is interchangeable allowing for change of blood analyte concentrations for development and testing of PPG-based sensors. The system was validated by black ink water compared to water and air compared to water testing to confirm optical transparency of the tube. The produced PPG signal, pulse rate and pressure change were compared to that seen in subjects. Optical transparency for 660 nm - 1550 nm wavelengths of light was validated with the signal, pulse rate and total compliance matching subject data. Thus, the system can mimic arterial pulses, creating a valid PPG signal that can be detected by PPG-based sensors.Clinical Relevance- Provides a low-cost, adaptable, physical PPG signal generator for research and development of optical medical sensor technologies.

Investigation of Narrow-band NIR LED Spectral Response Towards a Non-invasive Glucose Sensor.

Spectroscopy is utilised extensively in medical sensing technology. Typically, hand-held spectroscopy equipment uses miniature narrow-band light emitting diodes (LEDs) and photodiodes to emit and detect light, respectively. Photodiodes typically absorb light across a wide spectra so measurements can be corrupted by surrounding light. LEDs in the visible spectrum have a narrower spectral response and can be used in place of a traditional photodiode. However, the absorption characteristics of near infrared (NIR) spectrum LEDs is unknown. A discrete, low-cost spectrophotometer was designed to assess spectral response for 8 narrow band NIR LEDs. The normalised and raw spectral response determined the optimum detector for 1050 nm - 1300 nm is the 1450 nm LED, and the optimum detector for 1450 nm - 1650 nm emissions is the 1650 nm LED.Clinical relevance - Understanding the spectral response of narrow-band LEDs in the NIR spectrum will aid development of NIR hand-held spectroscopy medical devices.