Biosensor and a biosensing kit

A biosensor comprising a detection transistor and a reference transistor, both of a metal-semiconductor field-effect (MESFET) type, for detecting a target substance, wherein:

• the detection transistor comprises:
• an isolating substrate,
• a source electrode,
• a drain electrode,
• a first gate electrode,
• a channel for transmitting a drain-source current between the source electrode and the drain electrode, the channel being made of an oxide semiconductor, arranged on the isolating substrate and having the source electrode and the drain electrode arranged thereon,
• a sensitive substrate connected to the first gate electrode and comprising functionalization species for bonding the target substance, such that the first gate electrode connected with said substrate is sensitive to the target substance, and
• a second gate electrode arranged on the isolating substrate, physically separated from the first gate electrode by the channel, positioned opposite to the first gate electrode and configured to modulate the drain-source current of the channel;
• and wherein the reference transistor comprises:
• a reference source electrode,
• a reference drain electrode,
• a first reference gate electrode connected with an insensitive substrate without the functionalization species of the sensitive substrate, such that the first reference gate electrode connected with said insensitive substrate is insensitive to the target substance,
• a reference channel made of the oxide semiconductor, for transmitting a reference drain-source current between the reference source electrode and the reference drain electrode, and
• a second reference gate electrode physically separated from the first reference gate electrode by the reference channel,
• wherein the detection transistor and the reference transistor are both placed on the isolating substrate and electrically connected to one another, wherein the second gate electrode of the detection transistor is connected to the second reference gate electrode of the reference transistor.