The Electrochemical Aptamer-based (E-AB) sensors provide continuous and real-time monitoring of specific target molecules, including proteins, antibiotics, neurotransmitters, and more. Due to the cost-effectiveness compared to enzyme sensing assays, E-AB platforms hold significant promise for point-of-care devices and precision medicine. However, sensitivity remains a challenge, particularly in the complicated environment, such as blood and serum. While research has achieved a noise level in the picoampere range, enhancing sensitivity is crucial for detecting trace amounts of certain molecules, such as dopamine, in complex biological contexts. In this project, we propose an innovative charge-based electrochemical Aptamer sensor readout device incorporating a Sample and Hold (S/H) circuit to diminish noise current to the femtoampere range while maintaining millivolt-level changes in input voltage. For structure-switching aptamers, target binding leads to the conformation changes. Once a duplex is formed within the Debye layer on the electrode surface, a change in the surface charge leads to an equivalent voltage change at the transistor gate and can be detected as current after FET transduction. Our signals come from the electron transfer rate of the redox marker conjugated on our aptamers, therefore avoiding leakage-induced information loss is crucial. To address leakage issues, a tri-state switch is integrated. The special switch comprises 3 CMOS switches and a negative feedback buffer to maintain a consistent voltage level during the OFF phase and reduce current flow. There are 16 sensing cells within one FET array, and the control signals of the readout are generated by the on-chip scan chain. With the sensing arrays, spatial signal information can be collected from the signal mapping. With these attributes of low noise and minimal leakage, we believe the proposed device stands to significantly enhance the accuracy of E-AB sensing platforms, thereby contributing to advancements in implantable medical devices.
Project is currently funded by: Other