Miniaturised Wireless Power Transfer Systems for Neurostimulation: A Review

In neurostimulation, wireless power transfer is an efficient technology to overcome several limitations affecting medical devices currently used in clinical practice. Several methods were developed over the years for wireless power transfer. In this review article, we report and discuss the three most relevant methodologies for extremely miniaturised implantable neurostimulator: ultrasound coupling, inductive coupling and capacitive coupling. For each powering method, the discussion starts describing the physical working principle. In particular, we focus on the challenges given by the miniaturisation of the implanted integrated circuits and the related ad-hoc solutions for wireless power transfer. Then, we present recent developments and progresses in wireless power transfer for biomedical applications. Last, we compare each technique based on key performance indicators to highlight the most relevant and innovative solutions suitable for neurostimulation, with the gaze turned towards miniaturisation

The design of IPT system for multiple kitchen appliances using class E LCCL circuit

Since many years ago, kitchen appliances are powered up by cable connected. This create a troublesome case as wire might tangle together and cause kitchen table messy. Due to this, wireless power technology (WPT) is introduced as its ability is to transmit power to load without physical contact. This leads to cordless solution better in safety as the product can be completely seal, highly expandable power range. This work focuses on the design of WPT based on inductive approach to power up multiple kitchen appliances. The selection of inductive approach over its partners capacitive and acoustic is mainly due to high power efficiency. Class E inverter is proposed here to convert the DC to AC current to drive the inductive link. A 1 MHz operating frequency is used. To ensure the circuit is robust with load variations, an LCCL impedance matching is proposed. This solution is table to maintain the output power if there is a slight change in load impedance. Finally, the developed prototype is able to supply 50V utput which can achieve power transmission up to 81.76%

Induced voltage estimation from class EF switching harmonics in HF-IPT systems

One of the advantages of high-frequency inductive power transfer systems is the high tolerance to misalignment and large air-gaps. However, the inherently large magnetic field volumes can lead to coupling of additional foreign objects with the primary, causing possible detuning of the system and heating of the objects. These foreign objects and the conditions of the local environment can load the transmitter, which changes the induced voltage on the primary side. Unfortunately, the induced voltage is not directly measurable in an operating transmitter and the most straightforward way of calculating this variable, through a measurement of primary coil current and voltage, can cause a significant decrease in quality factor which reduces system performance. An integrated solution capable of estimating the induced voltage through other less invasive measurements in the primary is needed to ensure safety of operation through foreign object detection. Knowledge of the induced voltage can also be used to correct tuning mismatches where both sides of the link are active (i.e., in synchronous rectification and bidirectional systems). In this article, multiple candidate variables for estimating the induced voltage are assessed based on factors such as measurement practicality and estimation accuracy. It is demonstrated for the first time that a solution which is based on the measurement of only two variables, the amplitude of the fundamental frequency of the switching waveform and input current, can achieve state-of-the-art induced voltage estimation accuracy. These two variables, which can be obtained using simple cost-effective analogue circuitry, are used in a Gaussian process to generate a regression model. This is used to estimate induced voltages at any angle in an approximate magnitude range of 0–20 V with a normalized root-mean-square error of 1% for the real part and 1.5% for the imaginary part. This corresponds to detecting a plastic container with 1 kg of saline so..