Cheap and plentiful at the same time
The new technology has many advantages, says Widdershoven. ‘CMOS technology is cheap and you can use it to process large quantities of data. You do not need any lenses or light sources, which means you do not need to purchase an expensive microscope. Furthermore, the technology is easy to scale up.’ That is a most welcome improvement for cell biologists like Verhoeven. ‘At present, we can only examine individual cells if we want to know something about cell membranes. With this chip, you can examine hundreds or thousands simultaneously.’
Seeking the boundaries
Meanwhile, Lemay and Laborde continue exploring the boundaries of the technology. ‘In collaboration with Wageningen University, we are looking at what we can say about cell dynamics based on measurements with the chip, for example,’ says Laborde. ‘We will also investigate how sensitive the sensor is. One of the aspects we want to investigate is what the limits of the measurement technique are. What are the smallest objects we can still see?’ adds Lemay. ‘Electrodes are becoming increasingly smaller. The smaller the electrodes, the closer you can place them next to each other and therefore the smaller the particles you can see,’ says Widdershoven. ‘With this technology, it should be fairly simple to see objects that are smaller than what you could ever render visible using a light microscope,’ adds Verhoeven.
‘And with higher measurement frequencies, we can more easily see through cell walls or in liquids with a high salt concentration. At present, the highest frequency is still limited by the time that a row of transistors on the chip needs to be able to switch simultaneously. However, that speed is increasing in newer CMOS generations. Ultimately, this speed could well end up in the gigahertz range. That would open up new possibilities to extensively study inside and outside of living cells and small particles such as viruses,’ says Lemay.
Seeing a cell communicate
‘These are exciting times for biology,’ says Verhoeven. ‘We have had to invest some time in discovering exactly how we should interpret the electrical signals so that these can be translated into cell behaviour. Now that we have mastered that, I can see many possible applications for this technology. I think it should be possible to use this technique to follow how the ion channels in a nerve cell open and close in real time. You would then be able to see how such a cell communicates with its environment. That would really be spectacular.’