Photonic Crystal Stimuli-Responsive Chromatic Sensors: A Short Review

Abstract

Photonic crystals (PhC) are spatially ordered structures with lattice parameters comparable to the wavelength of propagating light. Their geometrical and refractive index features lead to an energy band structure for photons, which may allow or forbid the propagation of electromagnetic waves in a limited frequency range. These unique properties have attracted much attention for both theoretical and applied research. Devices such as high-reflection omnidirectional mirrors, low-loss waveguides, and high- and low-reflection coatings have been demonstrated, and several application areas have been explored, from optical communications and color displays to energy harvest and sensors. In this latter area, photonic crystal fibers (PCF) have proven to be very suitable for the development of highly performing sensors, but one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) PhCs have been successfully employed, too. The working principle of most PhC sensors is based on the fact that any physical phenomenon which affects the periodicity and the refractive index of the PhC structure induces changes in the intensity and spectral characteristics of the reflected, transmitted or diffracted light; thus, optical measurements allow one to sense, for instance, temperature, pressure, strain, chemical parameters, like pH and ionic strength, and the presence of chemical or biological elements. In the present article, after a brief general introduction, we present a review of the state of the art of PhC sensors, with particular reference to our own results in the field of mechanochromic sensors. We believe that PhC sensors based on changes of structural color and mechanochromic effect are able to provide a promising, technologically simple, low-cost platform for further developing devices and functionalities.

Porous Silicon Biosensor for the Detection of Bacteria through Their Lysate

“…Optical transducers however outperform most physical transducers as there is no influence of the nature of the sample or of external disturbances on the signal [6]. Optical biosensors can take many forms: waveguides [7], ring resonators [8], refractometers [9,10], surface plasmon resonators [11], optical fibers [12], or even photonic crystals [13]. Porous silicon (PSi) is one widely used optical transducer for biosensors [14].…”

Molecular Imprinted Polymers Coupled to Photonic Structures in Biosensors: The State of Art

“…PC structures have been extensively applied in microfluidics, telemedicine, smart materials and flexible sensors. In particular, over recent years, colloidal crystals have been employed as suitable optical platforms for the development of chemical, physical and biosensors based on a chromatic response under an external stimulus [ 54 ]. As an example, Figure 2 d depicts a PC composed by a periodic arrangement of regularly shaped elements with different dielectric constants; the periodicity in the dielectric materials produces a photonic band gap (PBG), so that certain wavelengths, due to the presence of the PBG, cannot propagate but is reflected.…”

Detection of isoprene traces in exhaled breath by using photonic crystals as a biomarker for chronic liver fibrosis disease

“…Optical biosensors are characterized by high performance, inexpensive, and compact design which can be inserted with a lab-on-a-chip device [12,13]. Photonic crystals (PCs) are considered fascinating optical sensors and biosensors in recent years [14][15][16]. PCs are periodic structures in 1D, 2D, or 3D designs that able to control the propagation of electromagnetic waves (E.M waves) within ranges of frequencies called photonic band gaps (PnBG).…”