Fish-inspired flow sensing for biomedical applications

Intravenous (IV) infusions, wherein the required medication is directly pumped into the patient’s bloodstream at a controlled rate using an infusion pump, represent a ubiquitous element of modern medicinal care. Although infusion pumps are a clinical boon, they are notorious for causing more injuries/deaths and being the subject of more FDA recalls than any other medical device. For instance, out of approximately 1.5 million adverse drug events (ADEs) that are reported to the FDA each year, around 54% are believed to be due to infusion pump errors, a further 61% of which are serious or life-threatening. A primary reason for this situation is that there is no way to verify the 'live rates' of an infusion which often causes over/under infusions and, consequently, costly ADEs. There thus exists a critical need and a market opportunity for a sensor capable of real-time monitoring of IV flows rates to prevent over/under infusions and avoid preventable ADEs.To address this problem, we take inspiration from the blind cavefish which is bestowed with ultrasensitive neuromast flow sensors capable of detecting extremely low water flows down to 1 µm/s. In this work, we develop artificial neuromast-like microelectromechanical systems (MEMS) flow sensors that imbibe the morphology and sensing principles of the blind cavefish, achieving high sensitivity and extremely low threshold detection limits. The MEMS sensor features a tiny hair-like structure that protrudes into the flow and translates the flow induced moment into a measureable voltage using a gold strain gauge patterned on a liquid crystal polymer (LCP) membrane. The sensors are ideal for IV flow sensing by being miniaturized (5mm×5mm), low-cost (< €1), ultrasensitive, biocompatible (polymer), accurate (< 10 ml/hr), low-powered (50 mW) and scalable (batch fabrication). Further, we describe a newly-developed, cleanroom-free, processing flow featuring 3D printing, soft polymer casting, and graphene drop-casting that can be used to fabricate flexible flow sensors. Our ultimate objective is to create low-cost and disposable microsensors that embed within the IV line to measure the real infusion flow rates and correct erroneous dosages through a feedback mechanism. This will allow remote monitoring of infusions, nurse workload reduction, and preventive maintenance. The technology has implications for safe homecare, healthy aging, and nurse shortage alleviation in the EU, and is expected to result in healthcare savings of €3mn per hospital per year, tapping into a market opportunity of €2b/yr.