Sensor measuring method and sensing apparatus
A method of performing a measurement with a sensor having a sensing surface and at least one capture molecule attached to the sensing surface for forming a binding pair with an analyte of interest, the binding pair having a flexible spatial orientation, the method comprising capturing the analyte of interest with the capture molecule, thereby forming the binding pair in an initial spatial orientation; applying a first electromagnetic force to the sensing surface to alter the spatial orientation of the binding pair; and performing a sensor measurement with the binding pair in the altered spatial orientation. A sensor apparatus implementing this method is also disclosed.
1. A method of performing a measurement with a sensor having a sensing surface and at least one capture molecule attached to the sensing surface for forming a binding pair with an analyte of interest, the binding pair having a flexible spatial orientation, the method comprising:
capturing the analyte of interest with the capture molecule, thereby forming the binding pair;
performing a sensor measurement with the binding pair in an initial spatial orientation;
applying a first electromagnetic force to the sensing surface to alter the spatial orientation of the binding pair, wherein the magnitude of the applied first electromagnetic force is less than the binding energy of the binding pair;
performing a sensor measurement with the binding pair in the altered spatial orientation;
deriving a sensor signal induced by the binding pair from the sensor measurement with the binding pair in the initial spatial orientation and the sensor measurement with the binding pair in the altered spatial orientation, wherein deriving the sensor signal induced by the binding pair comprises calculating a difference between the sensor measurement with the binding pair in the initial spatial orientation and the sensor measurement with the binding pair in the altered spatial orientation; and
repeating, at a predefined frequency, the steps of performing a sensor measurement with the binding pair in the initial spatial orientation, applying the first electromagnetic force, performing the sensor measurement with the binding pair in the altered spatial orientation, and deriving a sensor signal.
2. The method of claim 1 , wherein the predefined frequency is in the interval of 15-25 Hz.
3. The method of claim 1 , further comprising applying a further electromagnetic force to the sensing surface to bring the binding pair in the initial spatial orientation.
4. The method of claim 3 , wherein one of the first and further electromagnetic force is an attractive force and the other of the first and further electromagnetic force is a repulsive force.
5. The method of claim 1 , wherein the electromagnetic force is an electric force.
6. The method of any of claim 1 , wherein the electromagnetic force is a magnetic force.
7. The method of claim 1 , wherein the applied first electromagnetic force does not alter the spatial orientation of contaminants such that a signal contribution from the contaminants is filtered out from the derived sensor signal.
8. The method of claim 7 , wherein the sensor signal is a voltage, with the contribution to the sensor signal from the binding pair being an alternating voltage and the contribution to the sensor signal from the contaminants being a direct voltage.
9. The method of claim 1 , wherein the applied first electromagnetic force does not alter the spatial orientation of non-specifically bound elements such that a signal contribution from the non-specifically bound elements is filtered out from the derived sensor signal.
10. The method of claim 9 , wherein the sensor signal is a voltage, with the contribution to the sensor signal from the binding pair being an alternating voltage and the contribution to the sensor signal from the non-specifically bound elements being a direct voltage.
11. A sensing apparatus comprising:
a sensor having a sensing surface and at least one capture molecule attached to the sensing surface for forming a binding pair with an analyte of interest, the binding pair having a flexible spatial orientation;
an element that applies a first electromagnetic force to the sensing surface to alter the spatial orientation of the binding pair, wherein the magnitude of the applied first electromagnetic force is less than the binding energy of the binding pair;
wherein the sensing apparatus is configured to perform a sensor measurement with the binding pair in an initial spatial orientation and to perform a sensor measurement with the binding pair in the altered spatial orientation;
a processor that derives a sensor signal induced by the binding pair from the sensor measurement with the binding pair in the initial spatial orientation and from the sensor measurement with the binding pair in the altered spatial orientation, wherein the processor is configured to derive the sensor signal induced by the binding pair by calculating a difference between the sensor measurement with the binding pair in the initial spatial orientation and the sensor measurement with the binding pair in the altered spatial orientation; and
a controller for repeatedly, at a predefined frequency, performing a sensor measurement with the binding pair in the initial spatial orientation, applying the first electromagnetic force, performing the sensor measurement with the binding pair in the altered spatial orientation, and deriving the sensor signal.
12. The sensing apparatus of claim 11 , wherein the element that applies a first electromagnetic force is configured to alternate between an attractive electromagnetic force and a repulsive electromagnetic force.
13. The sensing apparatus of claim 11 , wherein the predefined frequency is in the interval of 15-25 Hz.
14. The sensing apparatus of claim 11 , wherein the applied first electromagnetic force does not alter the spatial orientation of contaminants such that a signal contribution from the contaminants is filtered out from the derived sensor signal.
15. The sensing apparatus of claim 14 , wherein the sensor signal is a voltage, with the contribution to the sensor signal from the binding pair being an alternating voltage and the contribution to the sensor signal from the contaminants being a direct voltage.
16. The sensing apparatus of claim 11 , wherein the applied first electromagnetic force does not alter the spatial orientation of non-specifically bound elements such that a signal contribution from the non-specifically bound elements is filtered out from the derived sensor signal.
17. The sensing apparatus of claim 16 , wherein the sensor signal is a voltage, with the contribution to the sensor signal from the binding pair being an alternating voltage and the contribution to the sensor signal from the non-specifically bound elements being a direct voltage.