Next Generation ‘Wearable’ Biochemical Sensors – Can Biomimetic Fluidics Help Deliver Much More Sophisticated Technologies?

There is a hierarchy of complexity in sensing technologies starting with (i) transducers for tracking physical parameters (temperature, colour, light level, location etc.), (ii) chemical sensors for monitoring chemical analytes (pH, ions, certain molecules), and finally, and most complex, biosensors for biological targets. Unlike chemical sensors and biosensors, physical transducers do not have to be in intimate (molecular level) surface contact with a sample to deliver the measurement. This turns out to be a key advantage, as transducers can be physically separated from the sample (e.g. temperature, light and colour sensing), or protected within a robust material (temperature sensing). In contrast, chemical sensors and biosensors must not only be in intimate contact with the sample, but in addition, their beautifully engineered surfaces must interact at the molecular level to generate a viable signal. This leads to changes in surface characteristics over time, which in turn causes a degradation in the quality of the signal, baseline drift, and loss of sensitivity and selectivity. Even worse, in many cases, biosensor function depends on delicate biomolecules to create the analytically useful signal. Not only are they unstable when exposed to the sample, but even storage can be a major headache. In addition, many biologically important measurements depend on tremendous binding power to provide the exquisite limits of detection and selectivity needed for practical application. Unfortunately, this in turn leads to irreversibility in binding, meaning that the devices can only be used once, which is why the field of biosensing is almost entirely dominated by single use, disposable sensing strips. And just to cap it off, detection of many important biological targets like viruses (e.g. COVID19!) require multiple steps to get to the final answer. This hierarchy of complexities is reflected in the reliability of technologies for wearable sensing and their migration towards practical applications. In this presentation, I will reflect on these challenges with regards to advancing wearable technologies for biochemical sensing, and offer some ideas on the role biomimetic fluidics might play in this regard