Frequently Asked Questions
In this section
Frequently Asked Questions
Q1: Can you explain "on-the-fly" printing?
A: This refers to the continuous movement of the print head during the printing process. Arrayjet microarrayers are fitted with the Xaar print head, an industrial-grade inkjet print head that travels at 20 cm.s-1 during printing. This translates to a printing rate of approximately 640 features per second, or the capability to print an entire 384-well plate, in triplicate onto 100 slides in less than 25 minutes.
Q2: What is inkjet printing?
A: Inkjet printing is the ejection, from a nozzle, of liquid droplets which travel a short distance (1 – 5 mm) through the air to land on a substrate in a predetermined pattern.
Q3: What are Arrayjet's key benefits versus other microarray printers?
A: There are many! Visit the Microarray Printers page for a video of the technology in action and a list of advantages to choosing Arrayjet technology.
Q4: What types of samples can Arrayjet microarrayers print?
A: Arrayjet microarray spotters are routinely used to print the following samples:
- Nucleic acid (oligos, PCR products, miRNA, PNA)
- Proteins (including lectin, glycoproteins, and recombinants) peptides and antibodies
- Cell and tissue lysates
- Serum, plasma, saliva and cerebrospinal fluid
- Aptamers (oligos and peptides)
- Hybridoma culture supernatants
- Carbohydrates, oligosaccharides, polysaccharides and glycoconjugates
- Nanoparticles and polymers
- Small molecules and compound libraries
- Micro-organisms (bacteria, viruses and phage)
Q5: What substrates are compatible with Arrayjet microarray printers?
A: Arrayjet microarrayers are inherently flexible and can print almost any sample type onto any substrate. Dedicated substrate holders are available for:
- Glass slides
- Membrane sheets (e.g. nitrocellulose, PVDF or nylon)
- Two-part 96 well microplates (e.g. Schott Nexterion MTP)
- Plastic microplates
We also routinely develop customer-specific holders for non-standard substrates such as point-of-care devices.
Q6: Can Arrayjet systems print into microplate wells?
A: Yes, Arrayjet systems can print into microplates with wells up to 4 mm deep. Standard Arrayjet-recommended plates have a working volume of 100 μl per well, and a printable area of 4 square mm. These can be supplied in a variety of materials, colours and surface chemistries to match customer applications. Alternatively, Arrayjet can help to develop plates and substrates to meet individual customer requirements.
Q7: What's the smallest spot size Arrayjet can print?
A: 60 μm. Spot size is determined by spot volume and the contact angle and relative hydrophobicity/hydrophilicity of the substrate.
Q8: How many arrays can I print with my sample?
A: From a single aspiration up to 6000 x 100 pL features of each sample can be printed. A minimum of 5 μL sample is recommended in each well. For example, this is sufficient to print:
- 3 replicates of a 200 pL feature onto 1000 slides – printed in under 5 hours
- 2x 100 pL replicates per well into thirty-one 96-well microtitre plates
- A 300 pL feature in duplicate on each of 16 pads on 50 slides
Before the start of the print run, the software will calculate if more than one sample aspiration will be required and notify the user. The user can then ensure sufficient sample volume is prepared.
Q9: How does Arrayjet technology protect against sample evaporation?
A: Arrayjet microarray printers are unique because they are compatible with the JetGuard™, a self-sealing silicon mat which creates a microclimate with 100% relative humidity around the sample. In-house experiments have demonstrated that within the first hour, aqueous solutions can lose over 10% of their volume from unprotected 384-well plates; Arrayjet's JetGuard™ effectively eradicates this source of variability. Arrayjet is the only microarray technology to use these septa, through which the JetSpyder™ can penetrate and access samples.
The JetGuard™ is also successful in protecting valuable samples from external contamination.
Q10: How is Arrayjet able to continually advance their technology?
A: Because Arrayjet builds all microarray printers on-site, the in-house software engineers, development scientists and manufacturing teams at Arrayjet work together to continuously improve the technology. Three areas of recent development include:
- Real-time printing evaluation by the Iris™ Optical QC System and automatic spot reprinting to ensure a 100% yield.
- Monitoring tools, including in-line controls to monitor and combat environmental changes.
- An expanded range of supported application, including microplate printing, development of glycerol-free buffers, ultra-low temperature printing and CMOS chip printing.
- A modern graphical interface and software flexibility to improve the user experience.
Q11: Do I have to use Arrayjet printing buffers?
A: No. Arrayjet has developed a range of printing buffers which produce high quality, consistent arrays with excellent spot morphology. Arrayjet customers are not limited to these buffers and the in-house development team can guide customers with assay-specific requirements, either suggesting suitable formulations or developing a unique buffer.
Arrayjet systems use a specially formulated hydraulic system buffer to drive all of the liquid handling operations and to clean the system between sample sets. Customers have access to all Arrayjet buffer formulations and protocols with the option to prepare them in-house or purchase pre-made volumes.
Q12: Are Arrayjet microarray printers suited to printing viscous samples?
A: Yes. Many biological samples are stored or supplied in solutions containing glycerol or gelatine, and owing to the non-contact print head, Arrayjet systems handle samples between 4 - 20 cP viscosity.
Q13: Do I have to add glycerol to my samples?
A: No. Arrayjet have developed glycerol-free printing buffers which are particularly useful for covalent immobilisation. Customers have access to all Arrayjet buffer formulations and protocols with the option to prepare them in-house, or purchase pre-prepared volumes.
Q14: Will piezoelectric printing heat my samples?
A: No. There is no heating generated during the Arrayjet printing process.
Piezoelectric printing induces an acoustic wave which initiates droplet ejection. The interior walls of the Arrayjet print head are made from the ceramic material lead zirconate titanate (PZT). When PZT is subjected to an electrical charge it changes shape, causing a volumetric change and a subsequent acoustic wave that ejects a droplet of the sample from the nozzle. There is no heating of the sample and no mechanical stress on the print head; nozzles consistently print even after actuation exceeding 10e13 per nozzle making this technology ideal for printing reliable microarrays.
Piezoelectric printing is sometimes confused with thermal inkjet, also known as bubble-jet, which uses the rapid heating of samples to create a pocket of gas to induce the required pressure for droplet ejection; this is not used by Arrayjet.