Remote surgery has been a game-changer in the medical field, allowing for surgeries to be performed from afar and providing access to medical services to remote and underserved communities. However, one major challenge that remote surgery robots face is the inability to recreate the sense of fine touch. This sense is crucial for surgeons to distinguish between cancerous and non-cancerous tissue, among other things.
To tackle this challenge, various solutions have been proposed, including the use of complex microfluidics or bulky actuators to create sensations of macro touch. But these solutions fall short in recreating the sensation of fine touch and texture. The good news is, research has shown there may be a new solution that promises to solve this problem - electrotactile stimulation using an array of electrodes.
My proposed solution uses electrical stimulation to stimulate specific small areas of the fingertips, which is accomplished by controlling each of the electrodes. To make the stimulation predictable, I'll be using a grid pattern for the electrodes, as it will allow for sensations to be created related to the boundaries between each electrode. The electrode pads should have as large an area as possible to minimize the resistance between each electrode.
The shape of the electrodes and the material used at the interface between the electrode and skin are also critical factors to consider. A conventional paired square-type electrode may not provide a high boundary length, so a different shape may be needed. The material used should not readily oxidize and should be biocompatible. For ease of use, a dry electrode array is ideal, but it may not be possible due to high skin-electrode resistance. In this case, a material such as gold- or silver-plated copper could be used, and an additional interface layer may be required to lower the skin-electrode resistance.
The electrodes will be controlled by a dedicated microcontroller that communicates with a host computer, which will send commands including the state of each electrode, amplitude, frequency, and wave type. To be used in virtual reality applications, a battery-powered system with wireless communication with the host computer is preferable. Each electrode should be configurable as either anodic or cathodic, or even as a tristate configuration to allow for a high impedance state so that current can be forced deeper into the skin to activate different nerves.
To ensure correct interfacing between the device and fingertip, skin electrode resistance monitoring should be used. This will not only ensure the device's safety but also monitor the quality of the skin-electrode interface and provide feedback on the stability of the connection.
For the application of electrotactile stimulation in remote surgery robots, a method of detecting texture must be used to interpret the material being touched by the surgical instrumentation. Piezoelectric devices have been demonstrated to capture texture data, and this data must then be interpreted and translated into data that will display the texture data on the electrode array connected to the fingertip.
To further optimize the design, simulation software can be used to simulate the current paths between electrodes and visualize the differences. The initial focus for stimulation parameters will be derived from previous studies and literature, including frequency, amplitude, and waveform. For example, research suggests investigating frequencies such as 5Hz, 250Hz, and 2kHz using sinusoidal, square, and pulsed DC waves. The ultimate goal is to transfer this knowledge to haptic feedback applications.
In conclusion, electrotactile stimulation using an array of electrodes holds promise in solving the challenge of recreating the sense of fine touch in remote surgery robots. With proper design and optimization, this solution could revolutionize the way surgeries are performed and provide better outcomes for patients.
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