Producing highly sensitive sensors requires many different steps and clean rooms that limit the amount of dust. Researchers from the Materials Science department at Kiel University (CAU) and from Biomedical Engineering at the Technical University of Moldova have developed a process to produce extremely sensitive, energy-efficient sensors using 3D printing, according to an article on Kiel University’s website.
The simple, cost-effective production method is suited for industrial production, the team recently explained in the journal Nano Energy. Their sensor is able to precisely measure the concentration of acetone vapor using a special structuring at nano level. As the acetone concentration in the breath correlates with blood sugar level, the research team hopes to have made a step towards producing a breath test for diabetics that could replace the daily checking of their blood sugar levels by finger pricks.
The sensors’ surface contains a thicket of nanowires measuring around 20 nanometers in diameter. The nano-wires-spikes increase the size of the sensor surface and so create its high level of sensitivity. “With a specially developed ink, we can apply these particles with precision to various surfaces using a 3D printer,” said Leonard Siebert, explaining what is known as “Direct Ink Writing.” A doctoral researcher in the “Functional Nanomaterials” working group at the CAU, Siebert is researching additive production technologies such as 3D printing.
The automated 3D printing process can create sensors within a few minutes, something which used to take a couple of hours in cleanrooms. The starting material can also be varied in a targeted manner, changing the size and structure and enabling the detection of a certain gas. “This is still, first and foremost, basic research, but this principle could be used in the future to develop sensors for hydrogen or other explosive and hazard gases,” said Professor Rainer Adelung, head of the working group at Kiel University.
The metal particles as the starting material for the sensors have to be of a certain size in order to form the special wires and nanospikes. “The correct and high ratio between surface and volume is crucial,” explained Dr. Oleg Lupan from Biomedical Engineering at the Technical University of Moldova.
When organic molecules meet the numerous wires in the finished sensor, the resulting chemical reaction changes the sensor’s resistance and releases clearly measurable signals. In principle, however, only a very small volume of electricity passes through the thin wires. “So our sensors only use very little energy,” explained Lupan. “This makes small portable measuring devices conceivable, too, which can be read directly via smartphone, for example.”
The researchers hope this could enable future use of the sensors in mobile, portable breath tests for diabetics. Instead of checking their blood sugar levels by finger prick several times a day, diabetics could measure the acetone content of their breath. The metabolic product is created when there is a lack of insulin and is emitted via the breath.