​A miniaturized piezoresistive flow sensor for real‐time monitoring of intravenous infusion
Drug overdose (DO) is considered one of the current issues of intravenous (IV) infusion particularly resulting in serious injuries and deaths. Malfunction of infusion pumps is reported as the main cause of the drug overdose. Live monitoring and flow rate calculation by health professionals have been practicing to avoid DO. However, human errors and miscalculations are inevitable. A secondary measurement tool is required to avoid the risk of OD when infusion pump malfunctions cannot be detected immediately. Here, inspired by nature, we developed a real‐time monitoring device through which an administrator can review, evaluate, and modify the IV infusion process. Our flow sensor possesses an erected polymer hair cell on a multi‐layered silicon base forming from a patterned gold strained gauge layer on a piezoresistive liquid crystal polymer (LCP) membrane. Gold strain gauges on an LCP membrane have been used instead of a piezoresistive silicon membrane as the sensing element. The combination of gold strain gauges and LCP membrane provides better sensitivity than a piezoresistive silicon membrane of the same dimensions and thickness. We also miniaturized our biocompatible sensor such that it can be possible to install it inside the IV tube in contact with the liquid providing an in‐suite online flow monitoring. The proposed LCP membrane sensor is compared with two commercially available IV sensors to validate its flow sensing ability. The experimental results demonstrate that the proposed sensor provides a low threshold detection limit of 5 mL/hr, which betters the performance of other commercial sensors at low flow rates.

Biomimetic artificial lateral-lines
Blind cavefish that survives in deep-waters, is bestowed with the finest set of flow sensors called neuromasts that enable the fish to detect minute water flow disturbances down to 1μm/s. Although blind, the fish accomplishes stupendous tasks like hydrodynamic vision and super-maneuverability. The artificial microelectromechnical systems (MEMS) sensors we developed, embrace the structural design and the sensing principles of the ingenious neuromasts sensors and attain ultrahigh sensitivity and accuracy. This work proposes the design, fabrication and experimental characterization of micro-sensors inspired by the superficial and canal neuromast sensors in the fish. The MEMS flow sensors developed could bring in a sea change in the abilities of current underwater vehicles and provide an irreplaceable alternative to the existing sensors. This proposal presents two types of sensors– LCP membrane haircell sensor for sensing steady-state laminar (dc) flow and Pb(Zr0.52Ti0.48)O3 piezoelectric membrane haircell sensor for sensing oscillatory (ac) flow. Through division of labor, these sensors form a system capable of performing a complete flow analysis. The word haircell refers to the vertically standing pillar in the sensor that extends into the flow and responds to the flow variations. It is called haircell since it works analogous to the biological haircells in the neuromast sensors in fish. LCP membranes are often good for achieving high sensitivities due to their low elastic modulus. On the other hand, PZT membrane MEMS sensors have been established to function excellently at higher frequencies and do not need any external power supply during operation. Therefore in order to perform a complete sensing of flow velocities and disturbances (ac flows) underwater, we designed two sensors, one for each purpose. We have successfully completed the design, batch-fabrication, in-lab and in-field characterization and accelerated reliability analysis of these biomimetic sensors.