F. Di Pietrantonio

Detection of odorant molecules via surface acoustic wave biosensor array based on odorant-binding proteins

In this paper, we present an array of biosensors for vapour phase detection of odorant molecules based on surface acoustic wave (SAW) resonators coated with odorant-binding proteins (OBPs). For the first time, the sensing capabilities of three different OBPs, as sensitive layers for SAW devices, are studied and compared. The SAW biosensor array is composed of three SAW devices coated by the droplet method with the wild-type OBP from cow (wtbOBP), a double mutant of the OBP from cow (dmbOBP) and the wild-type OBP from pig (wtpOBP). An uncoated device is used to compensate the variations of the environmental parameters. The SAW devices consist of two-port resonators fabricated on quartz (ST-cut, x propagation) with electrodes made of aluminium covered with a thin gold film (2 nm thick). The obtained surface densities of OBP layers are between 1.18×10(-6) kg/m(2) and 2.31×10(-6) kg/m(2) and were calculated measuring the resonant frequency shift of the SAW devices after the coating. The SAW biosensor array was tested in nitrogen upon exposure to vapours of R-(-)-1-octen-3-ol (octenol), in the range of concentration between 13 and 61 ppm, and R-(-)-carvone (carvone), in the range between 9 and 80 ppm. The highest sensitivity for detection of octenol (25.9 Hz/ppm) was obtained using the wtpOBP-based SAW biosensor, while the highest sensitivity for detection of carvone (9.2 Hz/ppm) was obtained using the dmbOBP-based SAW biosensor.

A surface acoustic wave bio-electronic nose for detection of volatile odorant molecules.

In this work, a bio-electronic nose for vapour phase detection of odorant molecules based on surface acoustic wave (SAW) resonators is presented. The biosensor system is composed of an array of five SAW resonators coated with three types of odorant-binding proteins (OBPs): the wild-type OBP from bovine (wtbOBP), a double-mutant of the OBP from bovine (dmbOBP), and the wild-type OBP from pig (wtpOBP). High resolution deposition of OBPs onto the active area of SAW resonators was implemented through laser-induced forward transfer (LIFT). The resonant frequency shifts of the SAW resonators after the deposition of the biomolecules confirmed the immobilisation of the proteins onto the Al/Au inter-digital transducers (IDTs). In addition, a low increase of insertion losses with a limited degradation of Q-factors is reported. The bio-electronic nose fabricated by LIFT is tested in nitrogen upon exposure to separated concentrations of R-(-)-1-octen-3-ol (octenol) and R-(-)-carvone (carvone) vapours. The bio-electronic nose showed low detection limits for the tested compounds (i.e. 0.48 ppm for the detection of octenol, and 0.74 ppm for the detection of carvone). In addition, the bio-sensing system was able to discriminate the octenol molecules from the carvone molecules, making it pertinent for the assessment of food contamination by moulds, or for the evaluation of indoor air quality in buildings.

Printing of amorphous and crystalline materials pre-machined using focussed ion beam patterning

Laser Induced Forward Transfer (LIFT) is a laser-based direct write technique which has been routinely employed for trials of the deposition of organic and inorganic compounds, polymers and biomaterials on various substrates for the realisation of devices such as OLEDs [1]. This single-shot printing approach, which allows a spatially controlled pixel-by-pixel deposition has been widely trialled for printing as it enables operation in a standard ambient environment, has the ability to print a wide range of materials, allows printing of multilayered stacks composed of dissimilar materials, allows printing on both structured and planar substrates, and beam shaping of the incident laser pulse is also possible to further control the size and shape of the deposited material.