Reusable electrode development

This page is dedicated to the development of good reusable electrodes:

In medicine, the physiological signals in the human body are captured using various kinds of electrodes. For the efficient use of electrodes on the human body, certain criteria need to be fulfilled. First of all, the electrodes need to be biocompatible, which means that the material performs its function without interrupting the body's physiological process and producing zero side-effects. The electrodes should display competent electrical performance with high tolerance and should be able to nullify internal noise. They should also be able to stick to the body for the required time.

Electrodes available on the market come in two forms, reusable and disposable. Lack of consumables such as ECG electrodes is frequently a cause of equipment collecting dust on the shelf (Malkin 2007). Consumables can add up to much more of the cost than the hardware in the end. Reusable electrodes is the way to go.

Limb Electrodes

These can be simply clamped around a wrist/ankle and are more easily constructed than precordial electrodes.

• Clamp

Clamp electrodes are simple, cheap and effective. These are likely to be the most useful replacements for disposable limb leads.
Pleasingly, it is possible to record a single lead rhythm strip (Lead II) using only clamp electrodes (one can also record leads I, III, AVR, AVF and AVL with only limb leads). Not all patients require 12 lead monitoring, particularly during general diagnosis. For example, drug overdose patients may be monitored for heart rate and emerging problems with lead II.
It is common for ambulances to record only a lead II rhythm strip prior to hospital admission.
Clamp electrodes may be unsuitable for long term monitoring as they can be constrictive for patients.

Precordial Electrodes

These need to be adhered in some way to the thoracic wall of the patient.

• Suction

Suction electrodes were popular in the early days of ECG usage. They are very reusable, suitable for quick diagnostic traces and simple to use. They suffer from several problems, including unsuitability for monitoring applications and long term recording, as well as bruising and difficulty applying to hairy or cachexic patients. They are also very difficult to steralise due to rubber components.

• Sticky

Sticky electrodes are simple to use, however they are unsuitable for continual reuse as sticky surfaces lose their stick, as well as becoming unsanitary.

• Hacked versions

Sticky electrodes can be modified and converted to reusable electrodes. This is advantageous for monitoring applications, however they need to be adhered to the patient, usually with tape (and this may not be as versatile as ordinary disposable electrodes). This is predicated on availability of tape. This idea originates from the Tata Main Hospital in India (Samaddar et al. 2002).
Professor Malkin thinks that a fabric or acrylic should work to get rid of the need for teflon used in this Indian hospital, and would allow direct construction on site.

Textile based electrodes

Recently a company called Textronics has received FDA clearance to market its textile-based ECG Electrode for use in general electrocardiograph monitoring and recording procedures. The company’s heart-sensing fabric offers a comfortable alternative to adhesive electrodes and metal wristbands that are commonly used with most ECG instruments on the market. While this technology is still not advanced enough for medical scenarios our devices is intended to be use in, it is something to look for in the future.

Recommendations

• Diagnosis (quick trace)

Clamp limb electrodes + suction precordial electrodes. Reusable sticky electrodes for precordial if suction unavailable.

• Monitoring (long trace)

Clamp limb electrodes for Lead II

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