Physical Sensors: Holographic Sensors

Abstract:

Holographic sensors are an exciting and versatile new addition to the analysts armamentarium which offer a number of advantages over conventional sensor technologies: They are an inexpensive and scalable platform amenable to mass production, configurable in multiple formats, including miniaturization, arrays and free standing flakes, and are able to output the results qualitatively or quantitatively as changes in color, intensity, two- and three-dimensional images and alpha-numeric displays and can be assessed visually and using smartphones. This review describes the basics of holography, how relatively simple holographic sensors were first developed and how the field has developed such that a plethora of key analytes including ions, gases, volatiles, metabolites, drugs, proteins, enzymes, inhibitors and whole cells could be monitored with holograms constructed with novel bespoke hydrophilic and apolar matrices and suitable embedded recognition-response systems. More recent developments such as molecular imprinting, combinatorial chemistry, increased reflectivity, new photopolymer materials, micro array technologies and improved modelling greatly enhance their selectivity, sensitivity and general acceptability. Nevertheless, despite a requirement for further research, this holographic sensor platform is highly versatile and can be configured to create visual or instrumentally monitored responses in discreet or real-time at macro, micro and nano scales.