Memsensor-Integrated Microrobots for Passive Detection of H₂O₂

A memsensor (a memory sensor) is designed as a sensor with/in memory, which can work in a passive mode and, hence, is particularly suitable for environments where a local/onboard power supply is hardly available for such a scenario: the microrobot will carry such sensors and move to a specific region where the physical quantities of interest are in the intermediate range. The sensors will be collected back with the robot to understand the information about the location where they have been staying. In this report, molybdenum disulfide (MoS₂) memsensors are integrated on microrobots for hydrogen peroxide (H₂O₂) detection in a passive mode. The sensing is based on the reactivity of a MoS₂ nanoflake to H₂O₂, which is an indicator of the existence of tumor cells in their microenvironment. The sensor has a crossbar configuration and is microfabricated with Au/MoS₂/Au. Due to its irreversible structure, calibration is done at a lower concentration of H₂O₂ and confirmed at a higher one while the effective sensing range is in between. Experiments show that the proposed calibration and sensing method has an acceptable resolution of 200 nmol/L to 2 µmol/L. Compatibility of the fabrication processes of the sensors to that of helical magnetic microrobots is excellent based on the first trial.

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