Frequently Asked Questions

Frequently Asked Questions

Q1: Can you explain on-the-fly printing?

A: The phrase 'on-the-fly printing' means that the printhead travels continuously during the printing
process. Arrayjet microarrayers use the Xaar XJ126 printhead, an industrially proven, 126-nozzle, shared-wall inkjet printhead; this travels continuously at 20 cm.s-1 during the printing process. This translates to a printing rate of approximately 475 features per second, or alternatively the ability 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 printers?

A: We have many benefits, the key ones being;

Accuracy & reproducibility; low intra and inter slide CVs utilising Xaar piezoelectric printhead technology with <5% CV, more specifically we have;

  • No sample build-up at the nozzle; samples are loaded directly into the printhead via the JetSpyder which means samples do not build up around the printing nozzles. Systems which dip the printing device directly into the sample will suffer sample build up and increased printing variability and clogged nozzles over time.
  • Nozzle accuracy; Arrayjet’s printing nozzles are made of thermoset polyimide. The nozzle apertures are laser ablated through the polyimide layer which gives superior nozzle accuracy.

Flexibility; able to print a variety of probes onto a wide range of substrates. Users can define spot volumes from 100 pL to 10 nL and there are no restrictions on pitch.

Time savings; high speed on-the-fly printing the fastest printing technology available. There are no time penalties or limitations to the number of samples printed simultaneously when printing multiple arrays on a substrate; i.e. it is as fast to print 16 or 96 well/pad substrates as it is a planar array.

Low running costs; robust, industrial proven printhead with no breakable tips or capillaries.

Economical sample usage; with the JetSpyder, a unique sample loading device used in conjunction with JetGuard, Arrayjet reduce dead volume, sample evaporation and sample wastage.

High volume throughput; range of 5 instruments with a maximum throughput of 1,000 slides in a fully automated printrun.

Modular, scalable technology; capacity and throughput can increase as your requirements increase, with the same core technology.

Q4: What types of samples can Arrayjet microarrayers print?

A: Arrayjet systems are routinely used for printing the following types of microarrays;

  • Nucleic acid (oligos, PCR products, miRNA, PNA)
  • Proteins (including lectins, glycoproteins, and recombinant) peptides and antibodies
  • Cell and tissue lysates
  • Serum and plasma
  • Aptamers (nucleic acid and peptide)
  • Hybridoma culture supernatant
  • Carbohydrates and oligosaccharides
  • Nanoparticles and polymers.

Q5: Do Arrayjet systems have the flexibility to print onto a variety of substrates?

A: Yes. Arrayjet microarrayers are highly flexible; we can print almost any sample type onto any substrate. We have dedicated substrates holders for the following;

  • 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

Q6: Can Arrayjet systems print into microplates wells? 

A: Yes. We can print into microplates with wells up to 4 mm deep. Our standard plates have a working volume of 100 μl per well, and a printable area of 4 mm2. We can supply these plates in a variety of materials, colours and surface chemistries to match your application. Alternatively, we can work with you to develop plates and substrates to match your application needs.

Q7: What's the smallest spot size Arrayjet can print?

A: 60 μm. Spot size is a function of spot volume and the contact angle, which is determined by the surface–tension of the sample being printed and the relative hydrophobicity/hydrophilicity of the substrate.

Q8: How many arrays can I print with my sample?

A: From a single aspiration you can print up to 6000 x 100 pL features of each sample. We recommend a minimum of 5 μL of sample in the well for one aspiration. 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
  • If more replicates are required, the system will automatically aspirate more sample as required

Q9: Is sample evaporation a big problem with Arrayjet microarrayers?

A: No. Arrayjet systems are unique because they are compatible with JetGuard™, a self-sealing silicon mat, which creates a microclimate with 100% relative humidity around the sample, thus minimising sample evaporation. Our experiments show 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 capable of using this technology, through which our JetSpyder liquid handling device can penetrate to access samples.

JetGuard also protects valuable samples from external contamination.

Q10: How has the Arrayjet technology developed over recent years?

A: With in house development and manufacturing teams we are able to continuously improve our technology. Three key areas of development include;

1. Improving the user experience a with vastly improved graphical interface and software flexibility.

2. Developing manufacturing monitoring tools, including in-line process controls to monitor and combat system drift and minimise instrument down-time.

3. Expanding the range of applications we support, including; microplate printing, a range of glycerol-free buffers for covalent immobilisation, low temperature printing, reverse phase protein arrays and CMOS chip printing.

Q11: Do I have to use Arrayjet printing buffers?

A: No. Arrayjet has developed a range of printing buffers, which are compatible with our technology and produce high quality, consistent arrays with great spot morphology. However our customers are not limited to these buffers, if you have assay-specific requirements, our development team can guide you on suitable formulations or develop something specific for you through our assay development service.

Arrayjet systems do use a specially formulated hydraulic fluid to drive all of the liquid handling operations and to clean the system between sample sets.

Our customers have access to all of our buffer formulations and protocols with the option to prepare them in-house, or purchase pre-prepared from us.

Q12: Can I print samples containing high concentrations of glycerol?

A: Yes. Many biological samples are stored in, or supplied in solutions containing glycerol and our system handles these samples effortlessly.

Q13: Do I have to add glycerol to my samples?

A: No. We’ve developed glycerol-free printing buffers, which are particularly useful for covalent immobilisation. These protocols are readily available to our customers, or buffers are available to purchase pre-made.

Q14: Will piezoelectric printing heat up 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 printhead are made from a ceramic material called lead zirconate titanate (PZT). When PZT is subjected to an electrical charge it changes shape causing a volumetric change and the subsequent acoustic wave ejects a droplet of sample from the nozzle. There is no heating of the sample and no mechanical stress on the printhead; nozzles consistently print even after actuations 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.