A novel and reproducible release mechanism for a drug-delivery system in the gastrointestinal tract

Active distance control in multi-capsule endoscopy via closed loop electromagnetic force between capsules

Capsule endoscopy offers a non-invasive and patient-friendly method for imaging the gastrointestinal tract, boasting superior tissue accessibility compared to traditional endoscopy and colonoscopy. While advances have led to capsules capable of drug delivery, tactile sensing, and biopsy, size constraints often limit a single capsule from having multifunctionality. In response, we introduce multi-capsule endoscopy, where individually ingested capsules, each with unique functionalities, work collaboratively. However, synchronized navigation of these capsules is essential for this approach. In this paper, we present an active distance control strategy using a closed-loop system. This entails equipping one capsule with a sphere permanent magnet and the other with a solenoid. We utilized a Simulink model, incorporating (i) the peristalsis motion on the primary capsule, (ii) a PID controller, (iii) force dynamics between capsules through magnetic dipole approximation, and (iv) position tracking of the secondary capsule. For practical implementation, Hall effect sensors determined the inter-capsule distance, and a PID controller adjusted the solenoid's current to maintain the desired capsule spacing. Our proof-of-concept experiments, conducted on phantoms and ex vivo bovine tissues, pulled the leading capsule mimicking a typical human peristalsis speed of 1 cm/min. Results showcased an inter-capsule distance of 1.94 mm ± 0.097 mm for radii of curvature at 500 mm, 250 mm, and 100 mm, aiming for a 2-mm capsule spacing. For ex vivo bovine tissue, the achieved distance was 0.97 ± 0.28 mm against a target inter-capsule distance of 1 mm. Through the successful demonstration of precise inter-capsule control, this study paves the way for the potential of multi-capsule endoscopy in future research.

Microrobots for Targeted Delivery and Therapy in Digestive System

Untethered miniature robots enable targeted delivery and therapy deep inside the gastrointestinal tract in a minimally invasive manner. By combining actuation systems and imaging tools, significant progress has been made toward the development of functional microrobots. These robots can be actuated by external fields and fuels while featuring real-time tracking feedback toward certain regions and can perform the therapeutic process by rational exertion of the local environment of the gastrointestinal tract (e.g., pH, enzyme). Compared with conventional surgical tools, such as endoscopic devices and catheters, miniature robots feature minimally invasive diagnosis and treatment, multifunctionality, high safety and adaptivity, embodied intelligence, and easy access to tortuous and narrow lumens. In addition, the active motion of microrobots enhances local penetration and retention of drugs in tissues compared to common passive oral drug delivery. Based on the dissimilar microenvironments in the various sections of the gastrointestinal tract, this review introduces the advances of miniature robots for minimally invasive targeted delivery and therapy of diseases along the gastrointestinal tract. The imaging modalities for the tracking and their application scenarios are also discussed. We finally evaluate the challenges and barriers that retard their applications and hint on future research directions in this field.

Performance Evaluation of a Magnetically Driven Microrobot for Targeted Drug Delivery

Given that the current microrobot cannot achieve fixed-point and quantitative drug application in the gastrointestinal (GI) tract, a targeted drug delivery microrobot is proposed, and its principle and characteristics are studied. Through the control of an external magnetic field, it can actively move to the affected area to realize the targeted drug delivery function. The microrobot has a cam structure connected with a radially magnetized permanent magnet, which can realize two movement modes: movement and targeted drug delivery. Firstly, the magnetic actuated capsule microrobotic system (MACMS) is analyzed. Secondly, the dynamic model and quantitative drug delivery model of the targeted drug delivery microrobot driven by the spiral jet structure are established, and the motion characteristics of the targeted drug delivery microrobot are simulated and analyzed by the method of Computational Fluid Dynamics (CFD). Finally, the whole process of the targeted drug delivery task of the microrobot is simulated. The results show that the targeted drug delivery microrobot can realize basic movements such as forward, backward, fixed-point parking and drug delivery through external magnetic field control, which lays the foundation for gastrointestinal diagnosis and treatment.

Intelligent automated drug administration and therapy: future of healthcare

In the twenty-first century, the collaboration of control engineering and the healthcare sector has matured to some extent; however, the future will have promising opportunities, vast applications, and some challenges. Due to advancements in processing speed, the closed-loop administration of drugs has gained popularity for critically ill patients in intensive care units and routine life such as personalized drug delivery or implantable therapeutic devices. For developing a closed-loop drug delivery system, the control system works with a group of technologies like sensors, micromachining, wireless technologies, and pharmaceuticals. Recently, the integration of artificial intelligence techniques such as fuzzy logic, neural network, and reinforcement learning with the closed-loop drug delivery systems has brought their applications closer to fully intelligent automatic healthcare systems. This review's main objectives are to discuss the current developments, possibilities, and future visions in closed-loop drug delivery systems, for providing treatment to patients suffering from chronic diseases. It summarizes the present insight of closed-loop drug delivery/therapy for diabetes, gastrointestinal tract disease, cancer, anesthesia administration, cardiac ailments, and neurological disorders, from a perspective to show the research in the area of control theory.