Two main methods have been employed in previous literature on piezoelectric power transfer through metal: practical experiment and simulation analysis. However, it is challenging to establish the power transfer model since the system generally works in the acoustic near-field region for high efficiency. Through-metal transmission systems based on PZT has been proven to be feasible. In the receiver (RX) side, PZT collect the elastic wave via the couplant and converts it to the electrical signal. At the transmitter (TX) side, modulated electrical signal is converted into elastic wave by a PZT, and the elastic wave is propagated through the couplant into the metal. A typical acoustic-electric system called sandwiched plate PZT (piezoelectric transducer) is shown in Figure 1. The piezoelectric materials can be used for bidirectional conversion between electrical signals and mechanical waves (ultrasonic waves) using piezoelectric effect and inverse piezoelectric effect. Īs elastic waves can easily propagate through metal barriers, it has attracted wide attention from academia and industry. Therefore, penetration-free techniques for transmitting data and power through metal barriers is demanded. However, physical penetrations inevitably impact the structural integrity and impermeability of metal shells. Traditionally, physical penetrations and wired feed-through have been the mainstream because wireless coupling is limited by the metal. However, power supply, control and communication between devices located on the isolated sides of metal barriers is always a challenging task taking into account the strength requirement. In order to improve the structural strength and anti-corrosion performance, metal materials are the first choice for underwater devices, aerospace equipment and radiation isolation facilities. Test through a 20 mm aluminum alloy plate shows that power transmission with efficiency 20.3% and data communication rate up to 38.4 Kbps can be achieved simultaneously. Extensive experiment has been done on evaluating the match between SEPAP transfer efficiency and the power transfer efficiency and analyzing the achievable data rate for bi-directional communication. Furthermore, we propose a low-cost and small-size prototype for simultaneous transfer of energy and bidirectional communication through metal by using two pairs of PZTs working on different resonant frequencies. Then we analyze the features of SEPAP and the factors impacting it by utilizing COMSOL. Hence, in this paper, we first propose the Spatial Equivalent Plane Acoustic Pressure (SEPAP), which is defined as the integration of the acoustic pressure over the receiving area, to model the pressure on the receiving PZT. The through-metal transfer efficiency of energy or data is determined by the relative pressure on the receiving PZT (piezoelectric transducer). Through-metal transfer of energy and data using piezoelectric transduce can avoid the potential leakage problem caused by physical penetrations and wired feed-through.

Piezo transducer