The University of Southampton

Author: Jessica Ewing

Your eyes are now obsolete

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After doing some research into interfacing electronic signals with the body, I stumbled upon bionic eyes. One device was the ARGUS II, implanted into five patients in England as part of a clinical trial. This article included praise from current ARGUS users Including a man who can now see his grandchildren running around. The articles surrounding the device was overwhelmingly positive until they got more recent then the narrative around ARGUS changed. 

The device is comprised of three modules. An electrode array, video processing unit and a camera. The brain interprets the signals as flashes and the vision created is more akin to an entirely new sense. In this video Ray describes the vision produced as arcs.

The arcs represent the most important parts of the picture. This should be moving objects and edges; the device must accurately pick out the pixels which will convey the most relevant information to the patient. The Video processing unit (VPU) is what does this. It utilizes edge detection algorithms like the matrix mechanics of convolution which I am familiar with from both computer science and quantum mechanics. 

An example of edge detection

The electrical components in the device have several purposes: data and power transfer and biological interfacing. The former is achieved by using magnetic induction. For data transfer the VPU unit encodes signals into radio waves. Which are then converted to tiny alternating currents by a receiver in the implanted region. The data can then be extracted from these currents. Power is transferred by the same physical principle tweaked for this purpose. The final challenge is at the biological interface. The ARGUS II uses micro-electrodes. These define the vision achievable by the device. Advancements in nano-tubes could really improve the quality of the vision created due to physical constraints of wider electrodes.

Despite the quality-of-life improvements seen from most recipients and the prospect of new iterations of devices the device manufacturer Second Sight collapsed and merged with Nano Precision Medical ceasing to develop its ARGUS implant line switching to other projects. The devices had never become profitable. All engineers were laid off and, unlike previously promised, support for the ARGUS models was stopped. Second Sight also failed to inform patients of the collapse. Now users are left to hope their device continues working as normal since replacement parts need to be sourced from the community and many relied upon devices have been rendered not functional by previously routinely fixed hardware issues.

In the EU manufacturers must provide spare parts for a washing machine for 10 years after the appliance has been discontinued. This law was introduced to help limit the environmental impact of E waste and protect consumers. The standard used for washing machines should be the absolute minimum used for implanted medical devices. I believe strongly in the right to repair and choose to repair my own technology, therefore qualified engineers should have access to the parts for device repair long after they have stopped being implanted. 

This is a prime example of our increasing vulnerability in the face of high-tech, smart and connected devices which are proliferating in the healthcare and biomedical sectors.

Elizabeth M Renieris, professor of technology ethics at the University of Notre Dame told the BBC https://www.bbc.co.uk/news/technology-60416058

Many have been left with defunct devices still implanted in their body. I believe the stress and anxiety caused for these people is unforgivable and the law needs to catch up, money and company reputation must stop being placed above patients and transparency.

The next generation of cardiac pacemakers 

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Due to a combination of academic interests including nano-fabrication, quantum physics and computer science; I began researching situations where quantum effects are used to interface with biological systems. It was down this line of inquiry I came across a research paper focused developing a novel form of pacemaker utilising light and microelectronics. Currently a pacemaker is a capacitor that discharges its electrical current to the heart. This leads to altering the pace of the hearts beating. The device also uses electricity to monitor the heart’s beating.  

The widespread adoption of pacemakers has saved an enormous number of lives. This is due to a multitude of heart conditions affecting the rhythmic beating of the heart. 50,000 people are fitted with a pacemaker every year in the UK. The first internal pacemaker was implanted in the UK in the 1960s. The first pacemakers were traumatic to implant and difficult to live with but subsequent advances combining the physics of the devices with the surgical methods used has led to the standard pacemaker being the size of a match box being implanted under local anaesthesia.

The increasing capability of microelectronics especially is allowing more in vivo studies of complete pacemaker devices in rodents. This has the potential to allow more novel technologies to be trialled. 

Researchers at the university of Arizona have developed a pacemaker that has a flower shape and uses light to stimulate the heart. Optogenetic stimulation utilizes light photons to activate excitable tissue. The circuitry integrated into the device also has the capacity to be loaded with machine learning algorithms, these would be especially useful in this kind of device as electrical sensing can be used simultaneously with photo stimulation to continually monitor the hearts beating. The device could then alter the timing of its stimulation to avoid latency that would reduce the performance of the heart. Another reason electrical stimulation may not be the optimum solution is that it causes damage to the stimulation site and is not specific to the cells that need to be stimulated, causing discomfort (although most users stop feeling the pulsing). 

This research is being done in a major part to the miniaturization of the pacemaker devices allowing trials on rodents that could not be achieved before.  

The device used an array of 9 micro-LEDs. And 8 22 micro-Farad Capacitors in parallel to achieve desired capacitance. It was powered by magnetic resonant coupling; this allowed the subjects to move freely within the magnetic field. The device used infra-red report data back wirelessly.  

If a form of this device makes it to human trials, it will not just have to demonstrate the effectiveness and safety of the system. There is also more scope for things to go wrong both within the device and when it interacts with external magnetic fields, as the system will present more potential points of failure. The more complicated the devices are electronically the more maintenance will be required. The electronics would more than likely need to be hard coded as a strong enough magnetic field would totally wipe many forms of non-volatile storage. The use of micro-LEDs also poses physical challenges due to the proximity required to the target cells of complex electronics as opposed to an electrode feeding from a device implanted next to the heart. 

A pacemaker is much more critical to a person’s moment to moment survival than other more periphery devices such as a replacement pancreas. So, there must be some certainty that the device equals or surpasses the abilities of the current pacemakers in use in its most basic objective of long-term patient survival. 

Introduction

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The concepts and assessment methods in this module are very different from my degree course which is Physics. Last semester I studied nano-physics this really interested me. I thought it would be interesting to get the chance to explore other disciplines than pure physics as many of the limitations of nano and micro physics are only apparent when looking through the lens of another subject, like many imaging techniques being destructive due to high energies required or needing thin or conducting substrates or very low temperatures due to thermal noise.