# Transmission at the center frequency (biosensor circuit)

#1

Hi,

Kindly refer the figure below;

I would like to know “how to define sensitive operating point”. The slope is approximately 67/RIU. How determine that “67”? The measure index changes, I understood but I confuse with the value of 67.

Please guide & feedback to me as soon as possible.

Really & always thanks for your support.

Best Regards,
Kalai

#2

Hi, Kalai

Here, sensitivity is simply the transmission/index_change slope. Therefore, according to this metric the circuit has maximum sensitivity when it operates near the point with maximum slope. Strictly speaking, to find the point you should calculate the respective derivative, which is quite straightforward provided that you have the calculated array.
More roughly, however, you can estimate the slope value visually.

#3

Hi Msaygin,

Understood. slope calculation= (Y changes / X changes). I got answer (66.67). Nearly to 67.

Thank You.

-Kalai-

#4

@kalaivani.tarumaraja

if you’ve got any further questions,