Non-invasive human breath sensor

In this paper, the design and development of a novel low-cost, non-invasive type sensor suitable for human breath sensing is reported. It can be used to detect respiratory disorders like bronchial asthma by analyzing the recorded breathing pattern. Though there are devices like spirometer to diagnose asthma, they are very inconvenient for patient's use because patients are made to exhale air through mouth forcefully. Presently developed sensor will overcome this limitation and is helpful in the diagnosis of respiratory related abnormalities. Polyvinylidene fluoride (PVDF) film in cantilever configuration is used as a sensing element to form the breath sensor. Two identical sensors are mounted on a spectacle frame, such that the tidal flow of inhaled and exhale air will impinge on sensor, for sensing the breathing patterns. These patterns are recorded, filtered, analyzed and displayed using CRO. Further the sensor is calibrated using a U-tube water manometer. The added advantage of piezoelectric type sensing element is that it is self powered without the need of any external power source.

MEMS based microactuator for microjet applications

The objective of this work is to confirm the possibility of utilization of PolyVinyliDeneFlouride (PVDF) films in MEMS based microactuator for microjet applications. A membrane type microactuator is designed, developed, packaged and tested. The microactuator consists of PVDF film attached to thin Silicon diaphragm. As the voltage difference is applied across it, due to the piezoelectric behaviour, it deforms primarily in d31 mode, which in turn deflects the diaphragm. Using finite element methods, coupled field analysis is carried out to optimize the dimensions of the actuator with respect to the output force and input voltage. A cavity with a square diaphragm of 1mm×1mm×5μm is realized using standard microfabrication technique. 50μm thick PVDF film, cut with special dicing saw, is glued inside the metalized cavity using low stress, conductive, room temperature cured epoxy. The 3mm×3mm×0.675mm actuator die is packaged using Chip-On-Board technique in conjunction with low temperature soldering for taking the connections. The micro-actuator is tested in both actuation and sensing mode. The developed actuator is proposed to use with micro nozzle to study the utilization in drug delivery system.