A MEMS turbine prototype for respiration harvesting

Abstract

Abstract. The design, manufacturing, and performance characterization of a MEMS-scale turbine prototype is reported. The turbine is designed for integration into a respiration harvester that can convert normal human breathing into electrical power through electromagnetic induction. The device measures 10 mm in radius, and employs 12 blades located around the turbine periphery along with ball bearings around the center. Finite element simulations showed that an average torque of 3.07 μNm is induced at 12 lpm airflow rate, which lies in normal breathing levels. The turbine and a test package were manufactured using CNC milling on PMMA. Tests were performed at respiration flow rates between 5-25 lpm. The highest rotational speed was measured to be 9.84 krpm at 25 lpm, resulting in 8.96 mbar pressure drop across the device and 370 mW actuation power.

Sensing Systems for Respiration Monitoring: A Technical Systematic Review

“…Few were the studies found in the systematic searches conducted in this review that harvested energy [ 77 , 84 , 104 ]. However, some energy harvesting techniques have been reported experimentally in other wearable systems [ 240 , 241 , 242 , 243 , 244 , 245 , 246 , 247 , 248 , 249 ]. This section presents a description of these techniques and how they were implemented in the respiratory sensing systems.…”

“…Other respiration-based energy harvesting systems can be found in the literature. The works of Delnavaz et al [ 240 ] and Goreke et al [ 241 ] used air flow to produce power with magnetic induction generators. On the one hand, the prototype of Delnavaz et al [ 240 ] was made up of two fixed magnets located at the ends of a tube (opposite poles facing each other) with a free magnet inside the tube ( Figure 13 B).…”

“…On the other hand, a microelectromechanical-scale turbine was presented by Goreke et al [ 241 ]. The turbine had 12 blades on its outer contour and ball bearings around the center embedded in grooves ( Figure 13 C).…”

“…This can also be inferred from the short battery life indicated by most studies that include this data (less than 12 h typically). Furthermore, the use of energy harvesting techniques in respiratory monitoring is another open research question, since the number of studies that implemented them is still residual [ 77 , 84 , 104 , 135 , 240 , 241 , 242 , 243 , 244 , 245 , 246 , 247 , 248 , 250 , 251 , 252 , 253 ]. Most studies presented laboratory experiments instead of functional prototypes.…”

“… Schemes of energy harvesting using magnetic induction generation: ( A ) DC generator activated by chest movements (figure inspired by Reference [ 135 ]), ( B ) tube with fixed and free magnets moved by airflow (figure inspired by Reference [ 240 ]), and ( C ) turbine moved by airflow (figure inspired by Reference [ 241 ]). …”