Wireless power transfer (WPT) in weak coupling has recently received widespread attention because it could be used to supply energy to capsule robots (CRs), allowing CRs (580 mW needed) to diagnose and treat diseases in the human body. In particular, exciting a three-dimensional (3-D) alternating magnetic field (AMF) for powering CRs has always been challenging since the randomly changing attitude and position can destabilize the induced power received by the coil on the CR. In this article, a novel WPT system based on three-dimensional hybrid transmitting coils (3DHTC) is proposed to generate stable energy for the CR. 3DHTC is a 3-D orthogonal coil system, consisting of a Helmholtz coil pair and two saddle-shaped coil pairs. The dimension of the 3DHTC is Φ70 × 35 mm. It can basically cover a 30 cm × 30 cm area of the human abdomen the design and implementation details of the new 3DHTC system are presented in this article. The 3DHTC system has been proven to excite a uniform and stable AMF covering the CR workspace by both analytical calculation and simulation analysis. Furthermore, a 1-D receiving coil (1DRC, Φ14 × 14 mm) is employed in the experiments to measure the AMF generated by the 3DHTC for its performance evaluation. The experiments illustrate the 3DHTC can supply stable energy of at least 777.63 mW to the 1DRC with randomly changing attitudes and positions, and the corresponding transfer efficiency ranges from 8.1% to 13.61%.

Wireless capsule endoscope (WCE) is a promising technology for noninvasive and painless imaging detection on gastrointestinal (GI) diseases. On the other hand, conventional endoscopes with wires could discomfort patients and cause them to vomit and aerosolize coronavirus if the patients are infected with COVID-19. However, there stands a technical bottleneck on power supply for the WCE. With the help of wireless power transmission technology, a hollow receiving coil (RC) is proposed to supply sufficient power and also minimize the size of WCE. A model on mutual inductance between transmitting and receiving coils is proposed to evaluate receiving power when the RC is in a different position and direction of patient’s GI tract. Based on the model, an optimal RC is built to obtain sufficient and stable power. Measurement of mutual inductance with the optimal RC validates high accuracy of the proposed model. The standard deviation of receiving power is very low. WCE with optimum RC gets sufficient power and captures images stably in live pig’s intestine tract. Additionally, the model is little affected by biological tissues. It ensures reliable performance of WCE and makes popular clinical application of WCE possible, which is also a relief to reduce epidemics like COVID-19.

Wireless capsule endoscopy (WCE) has been a great breakthrough in visually detecting the pathological changes of gastrointestinal (GI) wall, but the limit of viewing angle and power by batteries still hinder the wide application of WCE. In order to address these shortcomings, a dual-head video capsule system based on new type of receiving coils is presented. First, the dual-head video capsule system is designed, which could capture images of the whole GI tract in two channels, transforming the images into NTSC videos at a frame rate of 30 f s(-1) and transmitting the signals outside the body. Second, the wireless power transmission platform with new type of receiving coils is established to provide at least 108 mW of continuous, stable energy for the capsule. Then a prototype was fabricated and applied in animal experiments. The designed dual-head video capsule system is proved to be feasible and a potential solution for future clinical application.