An Ultrasonic Atomisation Unit for Heat and Moisture Exchange Humidification Device for Intensive Care Medicine Applications

Mahmoud Shafik

The state of the art of the existing heat and moisture exchange (HME) technology in use concludes that there are two main artificial humidification HME devices: active and passive device. The active device is complicated to use and expensive. The passive HME device is the preferred one, due to the ease of use and low cost. However it is not suitable for more than 24 hour use. This is due to current devices cavity design, limitations of HME materials performance and overall device efficiency. This paper presents the outcomes of the research work carried out to overcome these teething issues and presents a piezoelectric ultrasonic atomisation device for passive humidification device. This aims to improve the device heat and moisture exchange (HME) materials performance, by recovering the accumulated moisture, for a greater patient care. The atomisation device design, structure, working principles and analysis using finite element analysis (FEA) is discussed and presented in this paper. The computer simulation and modeling using FEA for the atomisation device has been used to examine the device structure.It also enabled to select the material of the active vibration transducer ring, investigate the material deformation, defining the operating parameters for the device and establish the working principles of atomization unit. A working prototype has been fabricated to test the device, technical parameters, performance and practicality to use in such intensive care applications. Experimental tests showed that the electrical working parameters of the device are: Current: 50 m-amps, Voltage: 50 volts, Frequency: 41.7 kHz. The atomization device has been integrated into the passive HME humidification device and initial results show some improvement in moisture return of the device by 2.5 mg per liter H2O. This is show the potential of the developed unit to improve the HME material performance in such working environment.