The drive to achieve sustainable laboratories affects all areas of operation. After the more obvious targets have been addressed, attention is shifting to other areas, notably fluorescence microscopy. Light emitting diode technology underpins this, details Isabel Goodhand.
Anyone working in a laboratory can’t help but notice how their day-to-day work can impact the environment – from single-use plastics to energy hungry equipment. While this might seem unavoidable, sustainable options are becoming widely available. In fact, many technologies and initiatives now exist to support the scientific community in the journey towards sustainable laboratories.
One such technology is LED illumination for microscopy. Although the widefield fluorescence microscope is a familiar sight in many labs, little thought is often given to the light source (unless it stops working). However, there is a world of difference between the traditional mercury or metal halide lamp and modern LED illumination systems, in terms of sustainability and performance.
LED illumination for sustainable science
Compared to lamps, the reduced environmental impact of LED Illumination Systems is largely down to two factors: conserving energy and avoiding mercury. An independent comparison study found that over 25,000 hours of use, a mercury lamp consumed 10 times more energy than an LED illumination system . This may seem surprising, but it is not just about energy efficiency. Energy is also conserved when considering the warm-up time required before a lamp can be used, and the cooldown period before it can be safely used again. Instead, scientists can quickly switch LEDs on and off as required, and illumination is immediately ready for use. This is a game changer for laboratories who find themselves leaving a lamp switched on all day to ensure availability when required. Considering increased energy prices, financial benefits are substantial. Although many laboratories do not pay directly for energy consumption, some facilities departments offer financial support for energy efficient equipment, which are sometimes known as ‘Green Grants’.
The toxic nature of mercury needs no introduction, but unfortunately this environmentally damaging substance is found in both metal halide and mercury lamps. Financial factors are also at play here, since disposing of old mercury lamps incurs extra cost. In fact, countries are moving towards banning mercury lamps altogether, since a viable alternative now exists (in the form of LEDs) . We would argue that LED technology for fluorescence illumination has now progressed beyond a viable alternative, and the good news is that scientists can make a sustainable choice while enjoying performance advantages.
The best of both worlds
Light emitted by lamps is a continuous white light spectrum, while LEDs emit narrower discrete bandwidths. ‘White light’ LED illumination systems do exist, although the facility to control LEDs separately is more popular, since selecting only the relevant LEDs reduces noise and enhances image contrast. LEDs can be controlled in many ways, such as by USB or TTL, and sequenced as complex protocols.
The irradiance can even be electronically modulated, making it far easier to reach the optimum light levels when compared to using neutral density filters, and this is especially important for minimising phototoxicity and photobleaching.
Moving beyond the standard control options, LEDs are built for speed and come into their own for studies capturing micro-second events using multiple channels. For this clever trick, we need to draw from multiple imaging technologies.
Sedat optical filter sets include single-band excitation and emission filters for maximum image contrast, and a multi-band dichroic mirror compatible with multiple fluorophores. Instead of housing the single-band filters in a filter wheel, switching between the channels to image each fluorophore, here we can avoid mechanical movement and speed up imaging by housing the single-band filters elsewhere:
• Excitation filters – many LED illumination systems with individual LED channel control allow excitation filters to be housed in the light source itself, in front of each individual LED. The speed is now determined by electronic switching between channels.
• Emission filters – An image splitter splits the emission light path in up to four images displayed on a different area of the camer a chip, and houses the emission filters.
LED illumination is a great example of a new sustainable technology. However, technology is just one part of the story when considering laboratory sustainability.
A sustainable future
Whether investing in new equipment or restocking consumables, sustainability can be factored in by utilising initiatives such as the ACT label, developed by not-for-profit organisation My Green Lab. Helping scientists understand the environmental impact of equipment, ACT (accountability, consistency and transparency), and is like an ‘econutrition label’ for lab products. Each label provides a score which reflects the complete environmental impact of manufacturing, using and disposing of a product and its packaging. For encouraging behavioural shifts, initiatives exist such as the Laboratory Efficiency Assessment Framework (LEAF) or the My Green Lab ambassador programme.
There is a world of difference between the traditional mercury or metal halide lamp and modern LED illumination systems, in terms of sustainability and performance
Many organisations now have sustainability officers to offer extra guidance and encouragement – and this points towards a change on the horizon as pressure is set to increase from funding bodies.
For example, the UK Research and Innovation (UKRI) Environmental Sustainability Strategy details a plan to consider environmental sustainability as part of funding decisions, grant and training terms .
Taken together, a picture of the not-sodistant future emerges where organisations support their laboratory staff to become more sustainable in their behaviour and equipment, which in turn helps to secure grants. Everyone is involved in making a positive change, and sometimes it is important to reconsider traditional technologies and ways of working.
Dr Isabel Goodhand is Technical Content Specialist at CoolLED
1 Green Light Laboratories (2017). mercury versus LED study. Available at: www.coolled.com/wp-content/uploads/2019/08/Green-Light-Laboratories-Mercuryversus-LED.pdf
2 United Nations Environment Programme (2019). Minamata Convention on Mercury. Available at: https://mercuryconvention.org/sites/default/files/2021-06/Minamata- Convention-booklet-Sep2019-EN.pdf
3 UK Research and Innovation (2020). UKRI Environmental Sustainability Strategy. Available at: https://www.ukri.org/wp-content/uploads/2020/10/UKRI-050920-SustainabilityStrategy.pdf