Recognition of Bimolecular Logic Operation Pattern Based on a Solid-State Nanopore

Design of a Current Sensing System with TIA Gain of 160 dBΩ and Input-Referred Noise of 1.8 pArms for Biosensor

This paper proposes a high-gain low-noise current signal detection system for biosensors. When the biomaterial is attached to the biosensor, the current flowing through the bias voltage is changed so that the biomaterial can be sensed. A resistive feedback transimpedance amplifier (TIA) is used for the biosensor requiring a bias voltage. Current changes in the biosensor can be checked by plotting the current value of the biosensor in real time on the self-made graphical user interface (GUI). Even if the bias voltage changes, the input voltage of the analog to digital converter (ADC) does not change, so it is designed to plot the current of the biosensor accurately and stably. In particular, for multi-biosensors with an array structure, a method of automatically calibrating the current between biosensors by controlling the gate bias voltage of the biosensors is proposed. Input-referred noise is reduced using a high-gain TIA and chopper technique. The proposed circuit achieves 1.8 pA_rms input-referred noise with a gain of 160 dBΩ and is implemented in a TSMC 130 nm CMOS process. The chip area is 2.3 mm², and the power consumption of the current sensing system is 12 mW.

DNA nanostructure-assisted detection of carcinoembryonic antigen with a solid-state nanopore

In this paper, a novel detection technique for tumor marker carcinoembryonic antigen (CEA) has been developed by using a solid-state nanopore as a tool. The system utilizes the specific affinity between aptamer-modified magnetic Fe₃O₄ and CEA, rather than directly detecting the translocation of CEA through the nanopore. The aptamer-modified magnetic Fe₃O₄ was hybridized with tetrahedral DNA nanostructures (TDNs), and TDNs were released after CEA was added. We investigate the translocation behavior of individual TDNs through solid-state nanopores. The frequency of the blockage signals for TDNs is recorded for indirect detection of CEA. We realized the detection of CEA with a concentration as low as 0.1 nM and proved the specificity of the interaction between the aptamer. In addition, our designed nanopore sensing strategy can detect CEA in real samples.