Unlocking the potential for oxygen concentrators in low resource settings
A write up of our collaborative meetups on energy efficiency, shelf life and humidity.
The global shortage of medical oxygen has become headline news since the global COVID-19 pandemic struck in 2020. As governments and healthcare providers around the world seek to provide this life saving medical resource it has become clear that the methods of generating, supplying and delivering oxygen to patients in, for example, the UK, Europe and the US, may not be the best solutions for other countries, particularly in low resource settings.
The Oxygen CoLab is a global network established in 2020 to enable, support and connect those working in the oxygen space and global healthcare, bringing together scientists, innovators, manufacturers, NGOs and institutions from all over the world to find a solution to the oxygen shortage. Specifically, the CoLab has been working together with its members to design oxygen concentrators that are fit for low and middle-income countries (LMICs) and low resource settings (LRS) around the world.
Oxygen concentrators entrain oxygen from ambient air by pressure swing adsorption, a process whereby air is passed through a molecular sieve bed at high pressure, bonding the nitrogen to the surface of the molecular sieve and allowing the oxygen to be piped off to the patient. The molecular sieve is then depressurized, releasing the nitrogen which is vented out of the system.
Such devices are already in existence and have been in use around the world for many years. However, oxygen concentrators have not been designed for use in the LRS found in many LMICs where high heat, humidity and dust as well as lack of access to reliable electricity result in the devices breaking down after a short period of time or even not working at all after an extended period in storage.
Over the course of several months in 2021, the Oxygen CoLab ran virtual workshops with its members from all over the world to work together on key challenges that must be overcome in order to create an oxygen concentrator that is fit for such contexts. The workshops focused particularly on protecting oxygen concentrators against poor quality power, improving their energy efficiency, their resilience against high humidity and their shelf life.
The results of these workshops — which highlighted the challenges and potential solutions specific to each question, as well as areas for further research and innovation — are summarized in the following series of reports made available by the Oxygen CoLab. It is our hope that they will provide a foundation of knowledge and experience for those working to build medical oxygen concentrators which deliver life saving treatment to those who need it most. Below is a high level summary of the workshops with a link to a more detailed article.
Energy Efficiency
Existing oxygen concentrators consume a lot of energy in order to run. Nearly a quarter of primary healthcare centres in sub-Saharan Africa have no access to electricity and many that do have access experience very poor reliability. Sadly, this is the reality in many countries around the world, which is why high performing, energy efficient concentrators are of vital importance.
Improving the energy efficiency of oxygen concentrators increases the viability of producing oxygen in remote health facilities using solar energy. This not only allows for the use of smaller solar panels and storage batteries, but also enables appliances to run for longer, particularly through the night when battery power is required to keep the concentrator running. Unlocking a remote clinic’s ability to generate their own oxygen would have very significant improvements on health outcomes. Increased energy efficiency also helps hospitals manage their power budgets and frees up power to be allocated to other vital uses such as refrigerators and incubators.
The following report summarizes discussions held during virtual workshops run by the Oxygen CoLab. It highlights two main approaches to improving energy efficiency:
(1) improving oxygen recovery (i.e improving the oxygen generating process to require less energy to produce more oxygen)
(2) improving the unit power efficiency of the compressor which is the most power hungry component of the concentrator system.
Specific knowledge, experience and ideas as to how this might actually be achieved are detailed in the following report from the Oxygen CoLab workshop on energy efficiency.
Click here to download the energy efficiency summary report from the CoLab workshop.
Shelf Life
The shelf life of an oxygen concentrator is the length of time that a new, unopened concentrator can be stored before you need to be concerned about whether it is fit for use. After this period of time the sieve beds would likely have degraded to a point where — when you switch on the oxygen concentrator — it would not operate at the levels of flow and concentration to meet the required standards.
The shelf life of an oxygen concentrator is important because it is not uncommon for devices to sit unused for considerable periods of time. For example, they might be stored in warehouses and spend substantial periods of time in transportation. There have been numerous cases of oxygen concentrators not functioning when taken out of storage. Furthermore, even when in use in clinics it has been noted that they can spend a considerable amount of time in storage between patients, which although not strictly a ‘shelf life’ issue, does lead to deterioration of the sieve bed caused by exposure to moisture.
Improving the shelf life of oxygen concentrators is of vital importance to ensure that these devices are able to function as intended when they are put into operational use. To solve the shelf life challenge, solutions must be found that take into account the whole journey of a concentrator: design & manufacture; packaging; quality control at the factory; transport; storage; user behaviour; and maintenance and repair. These are summarized in the following report from the Oxygen CoLab workshop on shelf life.
Click here to download the shelf life summary report from the CoLab workshop.
Humidity
Many existing commercial oxygen concentrators have been found to perform poorly under conditions of high heat and high humidity and ultimately fail more quickly. This can be compounded by poor user practices when operating the unit. Improving the performance and longevity of oxygen concentrators in hot and humid environments is a vital step towards designing concentrators that are able to withstand the conditions often experienced in LRS and LMICs around the world.
There are a number of ways in which current zeolite based oxygen concentrators could potentially be improved to withstand humidity, which include:
- Improvements to sieve beds (e.g the selection and ratios of adsorbent materials used in multi-layered beds, or dynamic adaptation of cycle times to prolong life of sieve beds)
- Improvements to columns (e.g. independent columns for drying and oxygen concentration that can be easily replaced or regenerated)
- Improvements to the concentration process (e.g employing vacuum swing adsorption to assist in the removal of moisture from the sieve bed)
- Pre-treatment of incoming air to make it as dry as possible before it enters the sieve bed
Any solution must take into consideration not only the operational environment of the concentrator but also protecting the sieve bed from moisture during the transport and storage phases as well. These are covered in more detail in the following report from the Oxygen CoLab workshop on humidity.
Click here to download the shelf life summary report from the CoLab workshop
