Microsensors

Miniaturized biosensor microtechnology for fast detection of contaminations from food (BIOMICROTECH – no. 52-173/2008)

- Development of miniaturized biosensors technology integrated in microfluidic chips, for the detection in the ng/L domain of organophosphorus insecticides from food (milk, juices from fruits and vegetables) and water by involving the microtechnology techniques on silicon and microbiology techniques.

- The sensitive acetylcholinesterase (AChE) amperometric biosensor proposed in the project is single use, reproducible, mass production, low cost and has commercial value.

- Two techniques studied, for surface functionalisation: the organofunctionalisation method (organic compounds with: thiol (-SH) group, amino (-NH2) group, medium modifier is organic group) and inorganofunctionalisation method (a metal (gold), Au<111>, for the adherence of the bovine serum albumin (BSA) to the substrate.

Self- assembled monolayers (SAMs) on silicon substrate comparative with polymer substrate for E- coli O157:H7detection (IMUNOSENSE (Miniaturized immunosensor arrays technology, for herbicide detection) national project, 2007-2010)

- Biosurface functionalized by SAMs (self assembled monolayers);

- Immobilisation of goat anti-E.coli O157:H7 antibody was performed by covalently bonding of thiolate mixed self-assembled monolayer (SAMs) realized on two substrates: polymer coated with gold and silicon coated with gold;

- The properties of the monolayer’s and the biofilm formatted with attached antibody molecules were analyzed at each step using infrared spectroscopy (FT-IR ATR), atomic force microscopy (AFM), electron microscopy (SEM) and the cyclic voltammetry (CV);

- The experimental results revealed the comparison between silicon and polymeric substrates and showed the investigations of each stage of the immobilization process taking into account in the same time the factors that influence the chemistry of the surface and the further interactions in order to realize a sensitive, specific and low cost immunosensor or a microarray for detection of E.coli O157:H7.

(A), (B) Polymer coated with gold reference three dimensional and two dimensional AFM image (2 µm); (C),
(D) Topographic images of the gold surface on silicon substrate after immersion in thiols ( 2µm),
(E) Topographic images of the gold surface on silicon substrate after immersion in thiols (1µm)

Inkjet printing technology for microsensor manufacturing

- Innovative technology, with no need for lithography, CVD, PVD processing, and high substrate processing costs.
- The capability to deposit droplets of fluid, of the picoliter magnitude, such as liquid silver or organic inks, on all types of surfaces, including flexible ones.
- The use of flexible substrates. Because of the cost advantage, PET (Poly-Ethylene-Terephthalate) sheets are often used because of their stability at high temperatures and eventually sheets of PEN (Poly-Ethylene-Naphthalate) and Poli-ANIline (PANI).