In order to make the gastrointestinal microrobot (GMR) expand and anchor in the gastrointestinal tract reliably, a novel expanding mechanism of the GMR is proposed in this paper. The overlapping expanding arm is designed to be used to increase the variable diameter ratio (ratio of fully expanded diameter to fully folded diameter) to 3.3, which makes the robot more adaptable to the intestinal tract of different sections of the human body. The double-layer structure of the expanding arm increases the contact area with the intestine, reducing the risk of intestinal damage. The kinematics and mechanical model of the expanding arm are established, and the rigid velocity, rigid acceleration, and expanding force of the expanding arm are analyzed. The elastodynamics model of the expanding arm is established. Through the finite element analysis (FEA), the velocity, acceleration, and the value and distribution of the stress of the expanding arm under elastic deformation are obtained. Based on the elastodynamics analysis, the structure of the expanding arm is optimized. By the structure optimization, the thickness of the expanding mechanism is reduced by 0.4mm, the weight is reduced by 31%, and the stress distribution is more uniform. Through the mechanical test, the minimum expanding force of the expanding mechanism is 1.3 N and the maximum expanding force is 6.5 N. Finally, the robot is tested in the rigid pipeline and the isolated intestine to verify the reliability and safety of the expanding mechanism.

Piezoresistive pressure sensors have broad applications but often face accuracy challenges due to temperature-induced drift. Traditional compensation methods based on discrete data, such as polynomial interpolation, support vector machine (SVM), and artificial neural network (ANN), overlook the thermal hysteresis, resulting in lower accuracy. Considering the sequence-dependent nature of temperature drift, we propose the RF-IWOA-GRU temperature compensation model. Random forest (RF) is used to interpolate missing values in continuous data. A combination of gated recurrent unit (GRU) networks and an improved whale optimization algorithm (IWOA) is employed for temperature compensation. This model leverages the memory capability of GRU and the optimization efficiency of the IWOA to enhance the accuracy and stability of the pressure sensors. To validate the compensation method, experiments were designed under continuous variations in temperature and actual pressure. The experimental results show that the compensation capability of the proposed RF-IWOA-GRU model significantly outperforms that of traditional methods. After compensation, the standard deviation of pressure decreased from 10.18 kPa to 1.14 kPa, and the mean absolute error and root mean squared error were reduced by 75.10% and 76.15%, respectively.

Intestinal-related diseases all around the world are increasing nowadays, and gradually become stubborn diseases threatening human health, and even lives. Diagnosis methods have attracted more and more attention. This article concerns a non-invasive way, a novel micro-robot, to diagnose intestinal diseases. This proposed micro-robot is a swallowable device, 14 mm in diameter, like a capsule. In order to make it possible for the micro-robot to move forward, backward, or anchor itself at a suspicious lesion point in the intestine with different lumen diameter sections, two key mechanisms have been proposed. One is an expanding mechanism with two-layer folded legs for anchoring. The designed expanding mechanism could realize a large variable diameter ratio, upwards of 3.43. In addition, a pair of specific annular gears instead of a traditional pinion drive is devised not only saving limited space, but also reducing energy loss. The other mechanism is a telescoping mechanism, possessing a self-locking lead screw nut system, which is used to obtain axial motion of the micro-robot. Then, the kinematics and dynamics of the micro-robot are analyzed. After that, the following experiments, including force tests and locomotion tests, are constructed. A good match is found between the theoretical results and the experimental data. Finally, in vitro experiments are performed with a prototype to verify the safety and reliability of the proposed micro-robot in porcine intestine.

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.

Approaches to studying electromagnetic induction in weak coupling have recently received attention in robotics since they could be used to supply energy to robots, allowing robots to diagnose and treat diseases in the human body. A three-dimensional orthogonal receiving coil connected in parallel, with a size of 13 mm × 13 mm × 13 mm, for an intestinal examination microrobot is designed in this article. Based on the defined attitude functions, we build and verify the stability and effectiveness of the proposed coil model through both analytical calculation and simulation analysis. In addition, to supply enough power to the microrobot, the number of turns of the receiving coil is optimized, considering both the electrical coil parameters and the limited space inside the robot. Then, an evaluation of the proposed 3D orthogonal receiving coil is presented in the bench tests. The results show that the power transmission efficiency can reach as high as 9.6%, with 1271 mW. This paper also uses a curved pipe to simulate the robot’s movement with the designed coil in the tortuous intestine. The average speed is 0.97 mm/s, with the path covering 180°. The experiments illustrate the excellent performance of the wireless power transmission, even when the positions of the two induction coils are constantly changing.

This article presents a novel puborectalis muscle artificial anal sphincter system (PM-AASS) with the module of sensory perception for treating severe faecal incontinence (FI). Due to the implantable feature of PM-AASS, this system applied low-power design and the total energy consumption could drop to 48.8 Ah/d. To reduce the injury of intestine and the pressure exerted on intestine, the actuator, including the structure of tings and the robot mechanism, of PM-AASS was presented and the middle ring was optimised. To realise the sensory perception, the intestinal flexible pressure sensors, comprising the radial sensors and the axial sensors, were designed. The sensors calibration showed the R-square of each fitting line were above 0.998, which presented a high goodness of fit and indicated we could figure out the pressure value with the analogue voltage captured by MCU. Through the in-vitro experiment, the results that the radial sensors were more relevant to the occlusion threshold while the axial sensors had more effect on the alarm threshold could be concluded. The practicability of the PM-AASS was verified by the results of the in-vivo experiment, which showed that the PM-AASS had the effect of improvement to the anorectal internal pressure.