The Langmuir-Blodgett(LB)technique is a way of preparing supramolecular organic thin films

which possess high order

uniformity

super thinness and a accurate control of film thickness

it is also harmless to substrates. Therefore

the films have shown considerable promise in frontiers of high technology research. In fact

the special functional systems can be assembled by LB technique on the basis of requirement molecular structures and the molecular packing and aligment are realized. The structure of the films as well as its physical properties are investigated and controlled at molecular level. At present

the LB films with specific functions have been successfully obtained such as monomolecular ultra thin insulating film

semiconducting film

conducting film and biological film

etc. In the early part studies of LB film were focused on the topochemistry. Since 1980's LB film technique is developed rapidly

it has been incorporatied with the research fields of condense state physics

material science

synthesis chemistry

microelectronic

biology and induced significant interest of scientists. The people desires to make novel sensitive mole electronic devices

optical non-linear devices

solar battery

optical switches of the information stores

bio-sensors

etc. We introduce mainly the history and preparation of LB films and research work of our group in over past ten years in this paper. The research results are described as follows. Firstly

we synthesized the substituted silicon phthalocyanine prepared

LB films

and obtained potential use in electronic device for the first time

and also reported the luminance diode with Au/LB film/ZnSe. Secondly

we have made great progresses in the synthesis of gas-sensitive materials and preparation of the films

and gas sensitive elements. We have synthesized firstly asymmetric and symmetric substituted copper phthslocyanine derivatives

and substituted phthalocyaninato-polysiloxane

the above materials were prepared for the gas-sensors used in detection of NH

3

. The sensitivity to NH

3

is 1×10

-7

and it reached the world levels of similar devices. Thirdly

we also studied on optical bistability of an optical waveguide coated with nonlinear Langmuir-Blodgett films by a prism coupling technique for the first time. The obtained threshold power densities of bistabilities were estimated to be 20MW/cm

2

32MW/cm

2

and 40MW/cm

2

respectively. The switching time is approximately 24ps. Fourthly

LB technique was applied in the biosensors and colorimetric transition process of polydiacetylene mannoside derivative LB films by binding Escherichia(E.coli)was investigated via UV-visible absorption spectra. The interfacial behaviors of the mixture at the air/water exhibited a good miscibility. In addition

we have analyzed the dynamical process of colorimetric transition caused by binding the E.coli to the mannoside derivative for the first time. It was estimated that one E.coli could only bind two mannoside molecules. We also describe a new method for using supramolecular assemblies composed of polydiacetylene supported on a electrode

which can provide easy and direct detection of bacteria through electrochemical technology. It utilizes an open platform to host biosensory elements allowing fast recognition and binding with the target molecules.