Detection of target species in a sample or liquid flow using diodes and an electrical signal

A method for detecting the presence of a target species in a sample containing a mixture of species including a biochemical reaction which involves a specific reaction of the target species to form a reagent-target pair, said method comprising the steps of:

• introducing electrical diodes bound to a binding species, said binding species participating in said biochemical reaction, into the sample in such a manner that the presence of the diodes in the sample is dependent on the presence of the target species in the sample;
• removing or separating diodes which are not bound to the target species:
• passing an alternating electrical signal having a known waveform through the sample;
• and
• detecting a modification of the waveform of the signal emerging from the sample, said modification of the waveform being due to the presence of diodes in the sample, the presence of the target species in the sample being derived from the detected modification of the waveform.

A method of monitoring the movement of a target species introduced into a system, said method comprising the steps of:

• removing a sample of the mixture from a particular location in the system relative to the point at which the target species was introduced into the system;
• introducing electrical diodes bound to a binding species into the sample in such a manner that the presence of the diodes in the sample is dependent upon the presence of the target species in the sample, said binding species binding to said target species;
• passing an alternating electrical signal having a known waveform through the sample;
• and
• detecting a modification of the waveform of the signal emerging from the sample, said modification of the waveform being due to the presence of diodes in the sample, wherein the presence of the target species in the sample is derived from the detected modification of the waveform.

A method of detecting the presence or absence of a leak in an otherwise closed system containing a target species, comprising the steps of:

• introducing electrical diodes bound to a binding species having affinity for the target species into the system in such a manner that the presence of the diodes in the system is dependent on the presence of the target species in the system;
• taking a sample from a location outside the system;
• passing an alternating electrical signal having a known waveform through the sample;
• and
• detecting the modification of the waveform of the signal emerging from the sample, said modification of the waveform being due to the presence of diodes having a binding species which binds to said target species in the sample, wherein the presence of the target species in the sample is derived from the detected modification of the waveform.

Apparatus for detecting the presence of a target species in a liquid, said apparatus comprising:

• a test chamber for containing the liquid;
• means for generating and passing through the test chamber an alternating electrical signal having a known waveform;
• and
• means for detecting any modification of the waveform of the signal emerging from the test chamber attributable to a presence of diodes in the liquid under test,
• wherein electrical diodes having a coating of a binding species capable of reacting specifically with the target species are introduced into the liquid contained in the test chamber.