Evaluating Energy Generation Capacity of PVDF Sensors: Effects of Sensor Geometry and Loading

Multiferroic Cantilevers Containing a Magnetoactive Elastomer: Magnetoelectric Response to Low-Frequency Magnetic Fields of Triangular and Sinusoidal Waveform

In this work, multiferroic cantilevers comprise a layer of a magnetoactive elastomer (MAE) and a commercially available piezoelectric polymer-based vibration sensor. The structures are fixed at one end in the horizontal plane and the magnetic field is applied vertically. First, the magnetoelectric (ME) response to uniform, triangle-wave magnetic fields with five different slew rates is investigated experimentally. Time and field dependences of the generated voltage, electric charge, and observed mechanical deflection are obtained and compared for four different thicknesses of the MAE layer. The ME responses to triangular and sinusoidal wave excitations are examined in contrast. Second, the ME response at low frequencies (≤3 Hz) is studied by the standard method of harmonic magnetic field modulation. The highest ME coupling coefficient is observed in the bias magnetic field strength of ≈73 kA/m and it is estimated to be about 3.3 ns/m (ME voltage coefficient ≈ 25 V/A) at theoretically vanishing modulation frequency (f→0 Hz). Presented results demonstrate that the investigated heterostructures are promising for applications as magnetic-field sensors and energy harvesting devices.

Highly Sensitive Ultrastable Electrochemical Sensor Enabled by Proton-Coupled Electron Transfer

Electrochemical sensors are critical to artificial intelligence by virtue of capability of mimicking human skin to report sensing signals. But their practical applications are restricted by low sensitivity and limited cycling stability, which result from piezoionic mechanism with insufficient sensing response. Here, we report a highly sensitive ultrastable sensor based on proton-coupled electron transfer, which is different from piezoionic mechanism. The sensor gives a high sensing signal output of 117 mV, which is 16 times higher than that of counterpart device (7 mV). It delivers excellent working stability with performance retention as high as 99.13% over 10 000 bending cycles in air, exceeding that of the best-known sensors reported previously. The flexible sensor displays high sensitivity in detecting real-time signals of human activities with large and subtle deformations, including wrist bending, moving speed, pulse wave and voice vibration. Smart functions, such as braille language and handwriting recognitions, are demonstrated for artificial intelligence.