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This article presents a frontend amplifier based on the 50-μm channel length n-type only indium-tin-oxide (ITO)-stabilized ZnO thin-film transistors (TFTs) on glass substrate. The amplifier has an external-bias ac-coupled, open-loop capacitor bootstrap structure. The area and power consumption are 41 mm² and 0.1 mW (8-V supply), respectively. Electrical measurement results show a gain of 20 dB, a bandwidth of 3 Hz-6 kHz, a common-mode rejection ratio (CMRR) up to 42 dB, an input impedance of 100 MΩ , and an input-referred noise of 106 μV $_{rms}$ (integrated from 1 to 200 Hz). The noise efficiency factor (NEF) and power efficiency factor (PEF) of the amplifier are, respectively, 248 and 4.9 x 10⁵, which is comparable among the state of the arts. The amplifier is successfully used to measure the heart-rate signal, which demonstrates its practicality.

Among the factors which restrict the large-scale utilization of magnesium-based hydride as a hydrogen storage medium, the high operating temperature, slow kinetics, and air stability in particular are key obstacles. In this work, a novel method, namely hydriding combustion synthesis plus short-term mechanical milling followed by air exposure, was proposed to synthesize air stable and autocatalytic magnesium nickel hydride (Mg2NiH4), which shows excellent hydrogen absorption/desorption kinetics, capacity retention and oxidation resistance. The short-term-milled Mg2NiH4 can desorb 2.97 wt.% hydrogen within 500 s at 230 °C. Even after exposure under air atmosphere for 67 days, it can still desorb 2.88 wt.% hydrogen within 500 s at 230 °C. The experimental and theoretical results both indicated that the surface of as-milled Mg2NiH4 was easy to be oxidized under air atmosphere. However, the in-situ formed Ni during air exposure of Mg2NiH4 improved the hydrogen desorption kinetics, and the formed surface passivation layer maintained the hydrogen storage capacity and avoided further poisoning, which we called autocatalytic and self-protective effect. Such a novel dual effect modified the reaction activity and oxidation resistance of the air-exposed Mg2NiH4. Our findings provide useful insights into the design and preparation of air stable metal-based hydride for large-scale utilization and long-term storage.