nh 2 is formed on the surface of hafnium dioxide sensing membrane 202 after the nh 3 plasma treatment as shown in step 103 of fig1 a 300 nm thick aluminum metal layer is formed on the back of si substrate to form an ohm contact layer as shown in step 104 of fig1 a negative photoresist of su8 2005 is used to define the sensing area of hafnium dioxide sensing membrane as shown in step 105 of fig1 the sensing area is immersed in 2 5 glutaraldehyde solution i e cross linking agent to form a glutaraldehyde layer the cross linking agent is used to immobilize the biological or chemical substance on the surface of hafnium dioxide sensing membrane the glutaraldehyde is often used as the cross linking agent there is an aldehyde group at every end of glutaraldehyde the aldehyde group at one end reacts with the amino group formed on the surface of hafnium dioxide sensing membrane and the aldehyde group at another end reacts with the amino group on the bio molecule to be immobilized thus the bio molecule can be immobilized on the surface of hafnium dioxide sensing membrane the present invention emphasizes the technique for forming the amino acid on surface the other cross linking agent may be used to substitute the glutaraldehyde finally as shown in step 106 of fig1 drop the bio reactor into the sensing area of hafnium dioxide sensing membrane to form the sensing thin film with the biological and chemical application the present invention immobilizes the bio reactor on the surface of hafnium dioxide sensing membrane the bio reactor has biological or chemical reacted molecules such as.