Differential sensing with bioFET sensors

A microfluidic system, comprising:

• a semiconductor substrate having a first surface and an opposite, parallel second surface;
• a first bioFET sensor having a first gate on the first surface of the semiconductor substrate and a second bioFET sensor having a second gate on the first surface of the semiconductor substrate;
• an isolation layer disposed on the second surface of the semiconductor substrate and having a first opening over the first bioFET sensor and a second opening over the second bioFET sensor;
• a continuous interface layer disposed in the first opening and the second opening;
• a readout circuit comprising a differential amplifier configured to measure a difference between signals associated with the first bioFET sensor and the second bioFET sensor;
• and
• a microfluidic network configured to deliver fluid to the continuous interface layer disposed in the first opening and the second opening, the microfluidic network comprising:
• a first inlet channel fluidically coupled to the first bioFET sensor and a second inlet channel fluidically coupled to at least the second bioFET sensor, and
• an outlet channel downstream of the first bioFET sensor and the second bioFET sensor.

A method of using a bioFET device, comprising:

• providing a first bioFET sensor having a first gate on a first surface of a semiconductor substrate and a second bioFET sensor having a second gate on the first surface of the semiconductor substrate, wherein the first gate is the same material as the second gate;
• binding capture reagents to a continuous interface layer disposed on channel regions of the first and second bioFET sensors;
• flowing a solution containing the capture reagents through a first microfluidic channel positioned over the first bioFET sensor and through a second microfluidic channel positioned over the second bioFET sensor;
• flowing a solution containing target analytes configured to bind to the capture reagents down the first microfluidic channel, but not the second microfluidic channel;
• flowing a buffer solution through the first microfluidic channel and the second microfluidic channel;
• and
• detecting a differential signal obtained from the first bioFET sensor and the second bioFET sensor.