I worte my thesis at development at the department of Elctron Devices at BUTE. During my work I joined into the development of Lab-on-a-chip (LOC) microfluidic devices, which could be able to analyze different chemical, biochemical processes. The development of modern medical devices which are performing analysises in a reliable, easy and fast way cost efficient way is nowadays extremly important. A such significant task is the identification of phenylketonuria (PKU) disease. The current time consuming and costy test procedure which based on development of bacteria can be replaced by means of phenylalanine ammonia-lyase (PAL) enzyme. The PAL enzyme as a biorecetpor is able to identify the faulty L-fenilalanin level effectively. L-phenylalanine is responsible for severe sympthomes of PKU. We started a development of a continous-flow microfluidic LOC device which could be able to idenfiy the disease by using PAL enzyme in the future. In the first phase a new technique had to be developed where the PAL enzyme can be injected in a lossless effective way through the LOC devices. I created a magnetic nanoparticle which can be easily oriented in a magentic field. Besides of the easy orientation of the particle the bonding of active PAL enzyme is possible. The main goals of the development process of nano particle are as follows particle size distribution, excellent surface properties and enzyme bonding capacity. During my thesis I created successfully a bioreceptor which can be manitpulated by magnetic field. The bioreceptor can be used together with a micro fiuld chip for identifing the disease.