Inkjet microarray printing vs. pin-spotting

What are the benefits of using a non-contact microarray printer?

   Contact pin-spotter

Arrayjet non-contact inkjet bio-printer

Pins or piezo? With repeated contact, pins can become clogged, bent, blunt or broken.  As a result, maintenance costs are typically higher than with non-contact technology. Arrayjet replaces troublesome pins with an industrial-grade print head that deposits by piezoelectric charge 'on-the'-fly', never coming into contact with the substrate. Less frequent maintenance is possible as non-contact parts have a longer shelf life and do not require regular replacement.
Flexibility Fixed pin placement limits the flexibility of spot spacing, array design and layout.  Changing array design often requires a different set of pin-heads. The Arrayjet print head utilises a full range of movement, operating less than 1 mm above the substrate. This allows complete control of printing parameters. Accurate spot-on-spot deposition enables printed volumes of 100 pL to 10 nL, without the need to change to a different print head.
Speed and efficiency Pin-printing is inherently slow, and this increases the time needed to print higher density arrays. Arrayjet builds the fastest microarray printers on the market, with each printer capable of depositing an impressive 640 drops per second.  An entire 384-well plate can be printed in triplicate, onto 100 slides in just 25 minutes.  This makes Arrayjet microarray printers well-suited to manufacturing high-density arrays for high-throughput screening.
Throughput Low yield and low-throughput instruments are not capable of printing large batches of slides at speed.  Printing repeated batches risks introducing variables to the arrays. Up to 48 384-well source plates can be loaded simultaneously. Arrayjet's Ultra Marathon II has the output capacity to print up to 1000 chips or slides, or 200 microplates in a single batch run.
Sample type Sample restrictions exist with some systems. Higher viscosity samples such as pectins tend to block pins.

Arrayjet microarray printers have been optimised to be compatible with most biological samples including proteins and peptides, nucleic acids, antibodies, cell and tissue lysates and carbohydrates. 

Small molecules dissolved in DMSO can also be printed.

Sample conservation Sample volumes can evaporate or adhere to pins and contribute to unnecessary sample waste.  The patented Jetspyder™ reduces dead volume and aspirates as little as 0.7 μL. Valuable samples are conserved, making for significant savings on running costs.
Sample evaporation  Slower print runs can lead to evaporation, changes in viscosity and sample concentration.  As a result, data acquired from pin-spotted arrays may be less reliable. Evaporation and concentration changes are preventable with the use of Arrayjet Jetguard™ seals.  The JetMosphere™ unit is installed as standard with the Marathon range of microarray printers and regulates extreme temperature and humidity changes that could otherwise contribute to sample evaporation.
Suitable surface chemistries Contact technology may not be compatible with increasingly popular chemistries such as hydrogel slides, and pins may damage delicate nitrocellulose membranes.  Arrayjet microarray printers are compatible with slides, MEMs and microfluidic chips, microneedles, and 96-well microplates. The non-contact printhead will not damage substrate surfaces.
 Missing spots There is the potential for missing features caused by drying of samples during long print runs, or from samples not sticking to the pin itself. Samples can run out before all the spots have been deposited, or they may not adhere to the pins at all. If pins are not cleaned effectively, samples may become contaminated and disturb the quality of data.

The Iris™ Optical QC System comprises twin cameras that sit either side of the print head.  Printing is evaluated in real-time and missing spots are automatically reprinted.  Users can pre-define preferred cleaning routines that purge and clean the JetSpyder™ and print head between aspirations to eliminate the potential for contamination.

"Doughnut" effects Pin-contact with substrates creates a ring-shaped feature with poor sample distribution that tends to be concentrated towards the outer edge of the spot.

Non-contact printing results in even sample distribution, creating reproducible arrays and assisting researchers to generate more reliable data.