Dear Joseph, We had the same question at the beginning of the year and we assisted to demos of the two machines. To me, the two liquid handlers are valid choices and the most appropriate one will ultimately depend on your specific needs as they have some differences.
First of all, both liquid handlers have well-designed and intuitive software. They are easy to setup and use. The pipetting technology is however different. The Dragonfly uses disposable syringes with a piston directly in contact with the solution. With this technology, there is no need of liquid classes definition and the machine handles perfectly water, pure glycerol, 50% PEG 8k and higher MW PEGs as well as pure isopropanol (without droplet formation). The solutions are aspirated from disposable reservoirs you fill with the desired volume of chemical. The dragonfly has two possible configurations: with 5 or 10 syringes. The model with 5 syringes is upgradeable to 10 syringes. You can easily perform screens with more than 5 components with the 5-syringe model. The machine accepts any SBS format plate. We use the dragonfly to prepare the screens then use the Mosquito to prepare our crystallization trials. The Scorpion uses a positive displacement head to handle a wide range of fluid viscosities. Several liquid classes are predefined to adapt the pipetting speed to the viscosity of the solution. The Scorpion uses regular Tecan tips of different volumes (without graphene). It is designed to perform custom screens as well as to reformat commercial screens from 10 mL tubes to masterblock. At the time we tested the Scorpion, the screen reformatting part needed custom setup of the viscosity of all the solutions (to optimize the dispensing time) but Art Robbins was always clear they would help for that. The deck can adapt a great number of solutions as mentioned in a previous post. The Scorpion accepts SBS plates and I think it can or will accept Linbro plates. In terms of footprint, the two machines are compact. In our case, we decided to obtain the Dragonfly because it is very fast to dispense (around 6-7 minutes to prepare a 96 well plate with 5 components), very accurate (we usually dispense total volumes less than 80 uL) and there is no cross-contamination as the syringes are never in contact with the plate’s reservoir. The absence of liquid classes configuration increases the ease of use of the machine. The screen designer is very intuitive and it is extremely easy to divide a plate into sub-screens. The software that drives the Dragonfly is also instinctive allowing to minimal user training. The software is under continuous development. Hope this helps and again, the choice between these two machines will depend on your specific needs. Ludovic
