Photochemistry LED Illuminator

Pacer’s Photochemistry LED Illuminator was developed for the research and analysis of photo‐chemistry samples. Our customer GSK, one of the world’s largest pharmaceutical companies, required an illumination platform to enable the standardisation of light sources, in order to evaluate the impact of wavelength and light intensity on a photochemical reaction. Solutions available on the market were not only prohibitively expensive, but were inflexible and did not allow the control over wavelength selection and optical power levels that GSK required.

Discussions with Pacer revealed that this was a project perfectly suited to Pacer’s UK Design and Build team.Design and manufacture of a bespoke instrument would require optoelectronics expertise, mechanical and electronic design engineering capability, thermal engineering skills, manufacturing facilities, experience of the design and calibration of specialist laboratory instrumentation – and almost certainly a degree of innovation!

Pacer’s engineering team designed the complete illumination system including the controller, LEDs, high power LED driver and cooler, to work in conjunction with a custom vial housing.The system was designed to use an LED array as a light source, in conjunction with a well plate to hold the photo‐chemistry samples.

The illumination system offers users the option to use LED arrays of 6 different standard wavelengths. Pacer came up with the idea of mounting the LEDs on cassettes for easy interchangeability, in either 24 or 48 well configurations. A metal housing sits on top of the cassette and holds the samples to be tested.The temperature of the LED array is monitored, and maintained within its optimum range via a Peltier‐Thermoelectric Cold Plate Cooler, capable of removing up to 200W of heat from the cold plate. When mounted and connected on the cooler, the array type is auto‐detected, and maximum output levels are set accordingly.

The custom LED driver module was designed to control the LED output power and mode of operation, which can be continual wave (CW), pulsed width modulation (PWM) or a combination of the two. The system is fully self-contained and just requires a 240V AC power supply.

The illuminator was designed and built to meet BS EN 61010 safety requirements for electrical equipment for measurement, control and laboratory use. Particular considerations were emission levels and eye safety. User safety was an important consideration throughout the design; it is crucial that the whole system is secured firmly when in use, and employs interlocks to ensure the LEDs are not powered when uncovered, to meet eye safety requirements.

GSK are very pleased with the end result – a flexible, user friendly, safe, bespoke Photochemical Reactor System which enables evaluation of the impact of wavelength and light intensity on a photochemical reaction. As a result of the evaluation carried out using the new system, it was found that only 40?% of the maximum light intensity was required while still maintaining reaction rate, allowing more reliable temperature control and lower energy consumption.

Feedback from GSK has been extremely positive:

“…this instrument is a great addition to our reactor kit. It offers a level of flexibility and reaction setup transferability that I have not seen on the market. I hope we can continue to work with PACER on future generations to continuously improve the utility and tractability.”

….Chemistry Team Development Lead

“By using a platform capable of varying light intensity, it has been possible to develop a protocol that uses only a fraction of the maximum LED power, thereby developing our understanding of power and cooling requirements, when scaling photochemical processes from the lab to an industrial platform.”

….final report conclusions

For more details please contact:

Matthew Ashton, Divisional Manager,  Pacer International           matthew.ashton at

Lee Edwards, S Investigator, Primary Continuous Manufacturing, GAC - Global API Chem - UK, RD Platform Technology & Science, GSK            Lee.J.Edwards at

GSK have published a related paper entitled A Detailed Study of Irradiation Requirements Towards an Efficient Photochemical Wohl‐Ziegler Procedure in Flow – this is available via the link below: