A printhead that fires droplets 60 times faster than older designs, while warming the ink by no more than 3.2 degrees Celsius. That is what scientists at KIST, a Korean government research institute, reported for a new bioprinting tool, and the gentle heat is the part that matters to anyone hoping lab-grown tissue will one day help patients. Early findings suggest the approach is promising, though it remains a laboratory result, not a treatment.
Why heat is the problem
Bioprinting builds three-dimensional structures, such as tissues, from bio-inks, mixtures of living cells and hydrogels. Inkjet methods can do it, but they have been a minority choice. A review in the journal Bioactive Materials noted that inkjet is fast but yields low cell densities, and that it handles only thin bio-inks, those below 10 mPa s in viscosity.
Heat has been a bigger obstacle. The most common inkjet designs are drop-on-demand, where the head releases a droplet only when told to. One version uses a heating element to form a bubble that pushes the droplet out. Temperatures there can pass 200 °C, which is why that version is rare in tissue work; one study found 15% of an enzyme’s activity was lost in printing. The alternative is a piezoelectric head, which uses a material that changes shape under voltage to push the droplet out. The same review described studies in which such printers handled breast cancer cell suspensions and skin cells. Fibroblasts printed with one system stayed viable and kept multiplying for up to seven weeks, and cellular tubes showed viability as high as 82% after 3 days of incubation.
What the Korean team built
Dr Byung Chul Lee of KIST headed the team, working with Dr Seung-Hyup Baek’s group and Professor Tae-Keun Kim’s group at Korea University. They made a multi-nozzle head from a thin film of the piezoelectric material PMN-PZT. Sixteen ejection units, set 300 μm apart, can be controlled one by one. That gave 16 times the driving efficiency of conventional methods, according to KIST.
In tests the head printed hydrogel droplets 32μm across, half the usual size, at 1.2 m/s. Heat generation fell by 73.4%, and the operating temperature stayed below 30 degrees Celsius. Cooler running matters because temperature-sensitive bio-inks can be damaged or deformed by heat. The results appeared in Sensors and Actuators B: Chemical.
KIST suggests uses in organoids, from artificial organ transplants to drug toxicity testing. Dr Lee said the team plans to commercialize a 3D bioprinter for organs suited to transplantation and toxicity evaluation, testing inks such as gelatin.
Patients should treat this as early-stage work. The transplant organs Dr Lee describes are a plan, not yet a product, and anyone with questions about transplant options should talk to their doctor.
Sources
- High-performance inkjet print head enhances bioprinting productivity – EurekAlert (KIST)
- 3D bioprinting for biomedical devices and tissue engineering: A review of recent trends and advances – Bioactive Materials
- Same review, introduction
