A novel type of humidity sensor based on Co2（oda）2（4

4’-bipy） modified quarts crystal microbalance（QCM） is presented

and effect of preparation conditions

different solvent and different modified quantity on sensor character is studied.The experimental results show that this humidity sensor has linear relation with frequency variation at range of 1.2 ×10-6

2

0×10-6 with correlation coefficient 0.999 03

sensitivity of 87.40 Hz/10-6 and detecting limit of 0.16 ×10-6（signal to noise ratio is 3∶ 1）.In addition

the sensor is also test in relative humidity at range of 11 %

9

5 %RH

result indicates that logarithmic change log Δf exhibits good linear relation wit

h %RH

and the linear equation is log Δf=1.414 2+0.018 18 %RH

R=0.999 65.The humidity sensor has characters of easy to fabricate

small size

good selectivity

high sensitivity

good stability

and provide a new method for humidity detection.