The traditional thermal gravimetric analyzer (TGA) has a noticeable thermal lag effect, which restricts the heating rate, while the micro-electro-mechanical system thermal gravimetric analyzer (MEMS TGA) utilizes a resonant cantilever beam structure with high mass sensitivity, on-chip heating, and a small heating area, resulting in no thermal lag effect and a fast heating rate. To achieve high-speed temperature control for MEMS TGA, this study proposes a dual fuzzy proportional-integral-derivative (PID) control method. The fuzzy control adjusts the PID parameters in real-time to minimize overshoot while effectively addressing system nonlinearities. Simulation and actual testing results indicate that this temperature control method has a faster response speed and less overshoot compared to traditional PID control, significantly improving the heating performance of MEMS TGA.

Resonant microcantilevers have the advantages of ultra-high heating rates, analysis speed, ultra-low power consumption, temperature programming, and trace sample analysis when applied in TGA. However, the current single-channel testing system for resonant microcantilevers can only detect one sample at a time, and need two program heating tests to obtain the thermogravimetric curve of a sample. In many cases, it is desirable to obtain the thermogravimetric curve of a sample with a single-program heating test and to simultaneously detect multiple microcantilevers for testing multiple samples. To address this issue, this paper proposes a dual-channel testing method, where a microcantilever is used as a control group and another microcantilever is used as an experimental group, to obtain the thermal weight curve of the sample in a single program temperature ramp test. With the help of the LabVIEW’s convenient parallel running method, the functionality of simultaneously detecting two microcantilevers is achieved. Experimental validation showed that this dual-channel testing system can obtain the thermogravimetric curve of a sample with a single program heating test and detect two types of samples simultaneously.

We report on the experimental demonstration of rapid thermogravimetric analysis (TGA) with minimized thermal lag using MEMS resonant cantilevers. Thanks to the miniature device size and unique thermal isolation structure design, the sample loading area at the cantilever free end can be heated up to 800°C and simulated to be stabilized within milliseconds, suggesting a theoretical ultrahigh ramp rate of up to $10^5{ }^{\circ} \mathrm{C} / \mathrm{s}$. Our experimental results also support such a high ramp rate up to $\sim 8 \times 10^3{ }^{\circ} \mathrm{C} / \mathrm{s}$, which is underestimated by the current measurement apparatus. Still, we demonstrate high-performance TGA measurements on calcium oxalate monohydrate using cantilever-TGA, which show much fewer deviations from theoretical 3-stage weight losses, as well as much fewer thermal lags, compared with those measured by the conventional TGA apparatus at the same ramp rates. Our MEMS resonant cantilevers hold promise for the high-efficiency, high-precision thermogravimetric analysis of materials in various fields.