Abstract
Multiple sensor electrodes, a supplementary electrode, a reference electrode, and signal-processing circuits were integrated on a single chip to develop a chip-shaped electrochemical sensing system. L-lactate and glucose were measured using on-chip working electrodes modified by polyion complex to immobilize lactate oxidase and glucose oxidase, respectively. Cyclic voltammetry measurements were conducted using an on-chip potentiostat. Selective and quantitative detection of glucose and L-lactate and the interference behavior were studied. Hydrogen peroxide generated by enzymatic reactions was detected by an increase in anodic oxidation current. Reaction currents at +0.7 V versus Ag/AgCl were used to obtain calibration plots. The measured dynamic ranges for L-lactate and glucose were 0.2–1.0 mM and 2.0–8.0 mM, respectively. The sensitivities were 65 nA/mM and 15 nA/mM, respectively, using a working electrode of 0.5 mm2. The 3σdetection limit was 0.19 mM and 1.1 mM, respectively. We have achieved multiple biomaterial detections on a circuit-equipped single chip. This integrated electrochemical sensor chip could be the best candidate for realizing point-of-care testing due to its portability and potential for mass production.
Highlights
Electrochemical sensors have attracted attention in recent decades because they have been used in clinical inspection, environmental assessment, and battery technology
We have successfully developed an electrochemical sensing system that integrates multiple working electrodes (WEs), a counter electrode (CE), an reference electrode (RE), and signal-processing circuits
We have successfully designed and fabricated an electrochemical sensing system with electrodes and a potentiostat integrated on a single chip
Summary
Electrochemical sensors have attracted attention in recent decades because they have been used in clinical inspection, environmental assessment, and battery technology. Some reports on miniaturizing the entire sensing system have appeared recently [11]. Bulky electrochemical instruments should be miniaturized for future on-site measurement applications. To fulfill these requirements, electrochemical sensors using complementary metal-oxide semiconductor (CMOS) circuits could be the best candidate [12,13,14,15]. The entire system can be integrated into a single chip using a standard CMOS technique and a few electrode fabrication processes, which is promising because of the potential for mass production. Our objective is to fabricate a compact intelligent sensor chip to realize a portable and reliable sensing system that combines CMOS technology and electrochemical sensors
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