Maximizing coupling strength of magnetically anchored surgical instruments: how thick can we go?

Abstract

This study suggests that the strongest configuration of currently available MAGS instruments is suitable for clinically relevant abdominal wall thicknesses. Further platform development and optimization are warranted.

Wireless Tissue Palpation for Intraoperative Detection of Lumps in the Soft Tissue

“…With the proposed platform, the workspace is a cylinder with a diameter of 35 cm and a length of 35 cm, centered on the source of static magnetic field. Considering that the abdominal wall thickness for severely obese patients (Body Mass Index ≤ 40 kg/m 2 ) is usually below 4 cm [32], the proposed platform is easily applicable to the vast majority of patients undergoing abdominal surgery. Nevertheless, if a larger workspace is required, either the source of magnetic field or the on-board magnetic field sensors can be adapted to meet the desired requirements.…”

Closed-Loop Control of Local Magnetic Actuation for Robotic Surgical Instruments

“…We generalize the approach to the case where the driving and the driven magnets are asymmetrical (i.e., different in volume and/or magnetization), and where the intermagnetic distance h between them can vary within a certain range. In particular, assuming that the average abdominal tissue thickness upon insufflation for a population that includes obese patients (body mass index > 30 kg/m 2 ) is 4 cm [27], we focus our analysis on h ranging from 2 cm to 7 cm. Within this range, we model the dynamics of the LMA actuation unit, quantify the amount of mechanical power that can be transferred, and investigate two alternative strategies for closing the control loop.…”

Electropermanent Magnetic Anchoring for Surgery and Endoscopy

“…The system is also purely passive (i.e., relies solely on permanent magnetic Neodymium Iron Boron (NdFeB) coupling) and has no electromagnetic component. In 2011, MAGS was evaluated for coupling distance [5] and a best-case drop-off threshold distance of 4.78cm was established (defined using a nominal load of 39g). To date the system has only been tested in porcine and human cadaveric models [8].…”

“…The primary advantage of electropermanent magnetic technology in clinical applications is stronger magnetic attraction of permanent magnets compared to electromagnets of a similar form factor, while eliminating the undesired magnetic 'pollution' by enabling on/off operation. The ability to instantaneously change the strength of the magnet, dependent on the required coupling distance would help to alleviate current issues of possible damage to a patients intervening tissue [5], [10]. This paper demonstrates the application of a fully controllable electropermanent magnetic coupling system between a permanent magnet inside of the porcine stomach and an electropermanent magnet (EPM) for external manipulation.…”