I am trying to use some inorganic metal oxides for nonenzymatic glucose sensor studies. I was trying to get amperometric responses for glucose. I am able get detectable current change for minimum 0.1mM glucose and above. But I think that I can go to more lower value, but in lower concentration of glucose the signal to noise ratio is very low and I am not able to find proper current change. I was constanly stirring the solution while doing amperometric studies which was the reason for the hgh noise. How can I reduce the noise. I tried to smoothen the data in origin but still I failed to get any presentable data. Please help in this matter.
Dhrubajyoti: I guess you want to INCREASE Signal to Noise ratio, not reduce it. You want higher signal and/or lower noise. The stirring is not an important source of noise in itself, but the magnetic stirrer you probably are using is. My advice is the following: 1) do not stir the solution with a magnetic stirrer, but with a small electric motor from above, a 5-10 cm rod with a flattened end touching the solution. Yoy can use any small motor. 2) Put the solution and the electrodes inside a faraday Cage, made with aluminum. Do not put the motor inside the faraday cage, just bore a hole above the solution to stir by introducing the rod. The cage works better if connected to a good earth terminal.
Enclosing the solution and electrode alone inside a Faraday cage may not solve the problem. But the external circuit is also a problem. You have not mentioned what are the components/devices you externally connected. In any case, use COAXIAL CABLES. What instrument is used to measure the current? What is the level of current? You can find the detection limit of your circuit by replacing your solution/electrodes with a known current source and you wont be able to detect anything smaller than that with your sensor.
for finding minimum signal to noise ratio. you must use very small glass bead for sterring in the solution and by managing the speed of raotation you can find minimum base current. Before doing amperometry experment you can left your electrode over night in the solution. the conc. of material on the electrode is also an important factor for base current, maintain this. All the above factor done by me and find better results. so you can do and check the response. Best of luck.
Thank you all for your help and suggestion to find the problem.I am using Biologic VSP electrochemical work station. The level of current is in microamperes but I believe that my instrument has more detection limit than this. I was doing some mistakes. I will try to use Faraday cage and mechanical stirring. I was extending the coaxial cables by one normal cable, I will use coaxial cable in future.
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