Highly Sensitive Readout Interface for Real-Time Differential Precision Measurements with Impedance Biosensors

• Published in: Biosensors (Basel) Vol. 13; no. 1; p. 77
• Main Authors: Neshani, Sara, Momeni, Kasra, Chen, Degang J, Neihart, Nathan M
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 02.01.2023; MDPI
• Subjects: Algorithms; Bandwidths; Biosensing Techniques; Biosensors; Commercialization; Configurations; Data acquisition; Data processing; Design; Design parameters; Electric Impedance; Electrodes; Impedance; impedance biosensor; Interfaces; low-cost; Microcontrollers; precision; readout; Real time; sensitive; Sensors; Signal to noise ratio; Time measurement; Transducers; Tropical diseases; real-time; precision; impedance biosensor; low-cost; sensitive; interface; readout
• ISSN: 2079-6374; 2079-6374
• DOI: 10.3390/bios13010077

Field deployment is critical to developing numerous sensitive impedance transducers. Precise, cost-effective, and real-time readout units are being sought to interface these sensitive impedance transducers for various clinical or environmental applications. This paper presents a general readout method with a detailed design procedure for interfacing impedance transducers that generate small fractional changes in the impedance characteristics after detection. The emphasis of the design is obtaining a target response resolution considering the accuracy in real-time. An entire readout unit with amplification/filtering and real-time data acquisition and processing using a single microcontroller is proposed. Most important design parameters, such as the signal-to-noise ratio (SNR), common-mode-to-differential conversion, digitization configuration/speed, and the data processing method are discussed here. The studied process can be used as a general guideline to design custom readout units to interface with various developed transducers in the laboratory and verify the performance for field deployment and commercialization. A single frequency readout unit with a target 8-bit resolution to interface differentially placed transducers (e.g., bridge configuration) is designed and implemented. A single MCU is programmed for real-time data acquisition and sine fitting. The 8-bit resolution is achieved even at low SNR levels of roughly 7 dB by setting the component values and fitting algorithm parameters with the given methods.