DropPen: Small droplet chips speed up diagnostics and biomedicine
Researchers have developed chips that can be used to quickly generate microscopically small reaction chambers for diagnostic testing and biomedical applications.

Päivi Saavalainen, a geneticist and docent at the University of Helsinki, has together with her team developed DropPen, a small and portable device that offers a quick, easy-to-use and inexpensive solution based on droplet technology.

Droplets are small emulsion drops of water mixed in oil. They are used in diagnostics and biomedical research as microscopically small reaction chambers.

Droplets are utilised in, among others, digital polymerase chain reaction technology (dPCR), which helps, for example, measure very small numbers of pathogens or even individual cancer cells in clinical specimens. The technology also enables increasingly accurate analysis of cells and the culture of individual cells inside droplets.

At the moment, the technique requires large, complex and slowly functioning equipment that costs tens of thousands of euros. Such equipment is not suited to rapid diagnostics.

According to Saavalainen, these were the problems from which the DropPen innovation stemmed.

“We got frustrated by currently available pumps and devices that are complicated and expensive. We started considering how to generate droplets through much simpler means.”

Benefits for developing countries, field hospitals and special laboratories

DropPen is a single-use droplet chip in whose channel system an emulsion is formed through pressurisation with a portable and manually operated device. No separate pump equipment is needed. Reactions are carried out in the same chip, from which the results are directly scanned and analysed.

Saavalainen believes that the small size and rapid functioning of the device and chip make it possible, for the first time, to develop rapid diagnostic tests. Single cell analytics will also become more widely available, which means, among other things, that DNA can be individually analysed from a large number of cells.

“Inexpensive portable equipment will also be of use to developing countries, field hospitals and field research as well as laboratories specialised in infectious diseases. It’s not easy to make expensive and sizeable dPCR equipment available for them,” she notes.

Optimisation and testing

DropPen is the result of three years of research and development, from single cell analytics and the fabrication of microfluidic chips to novel uses, with two projects funded by Business Finland.

Päivi Saavalainen leads the Immunomics research group at the Faculty of Medicine. Alongside Saavalainen, geneticist Pinja Elomaa and chemist Benedek Poor work in the DropPen project, in addition to which cooperation is conducted with a research group headed by Christina Liedert at VTT Technical Research Centre of Finland and another research group at the Lappeenranta-Lahti University of Technology LUT, headed by Kari Ullakko.

According to Saavalainen, both the market and demand for single cell analytics and dPCR technology are seeing strong growth. She believes that the portable nature of DropPen as well as its inexpensive price offer a significant competitive edge. Another factor adding to its potential is the speed of the technique and its sensitivity in rapid testing.

“With our DropPen solution, dPCR technology could be utilised in the rapid diagnostics market,” she says.

In cooperation with VTT, the researchers are currently optimising DropPen prototypes for mass production and testing them on a range of applications. Trials with pilot customers are also being planned. The project, funded by the New Business from Research Ideas scheme of Business Finland, will run until next summer.

“After that, we will either establish a spin-out company for chip commercialisation or give other companies a licence to use the technology. We are also going to apply for a patent,” Saavalainen says.

Saavalainen says that, at the moment, the DropPen team is applying for initial seed funding as well as looking for partners in diagnostics, single cell analytics and digital imaging.