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Biosensors are developed through microneedle printing technology
A new production method using conductive inkjet printing enables low-cost, large-scale manufacturing, with potential applications in the diagnosis and monitoring of health conditions
By: Fernanda Zibordi*
Art by: Simone Gomes
The needles were constructed using a conductive substance with silver nanoparticles for electrochemical testing – Photo: Extracted from article
Microneedles are small instruments mainly used in the health field for painless drug delivery. They also play an important role in areas such as precision agriculture and personalized medicine.
In an article published in the journal Scientific Reports, researchers report the development of a new method of producing microneedles based on the printing of inkjets. Utilizing a conductive substance with silver nanoparticles, the process has been shown to be less costly and more suitable for large-scale productions by the adaptability of structures and materials that can be used.
Within the work of diagnosis and monitoring of health conditions – whether for animals or plants – biosensors allow access to more accurate information. They are small devices used to identify substances present in biological processes such as enzymes, proteins and nucleic acids. By contacting one of these biological recognition elements, the biosensors are able to convert chemical changes into electrical signals that can be quantified.
Microneedles are commonly used in the construction of these devices, but they often require “multi-step manufacturing processes that are typically expensive,” explains Gustavo Dalkiranis, a postdoctoral researcher in thermoelectricity at USP’s São Carlos Institute of Physics (IFSC) and one of the study’s authors. According to him, the goal of the research was to develop microneedle prints using conductive inks, eliminating the need for a separate metallization step.
In addition to lowering costs by simplifying steps, the alternative production proposed in the study does not employ sophisticated printing equipment. “It would be like a printer we have in offices, but this would be an industrial printer, in which we can put the inks that are of interest to us,” says Patrícia Deroco.
The postdoctoral researcher at the Chemistry Institute of the State University of Campinas (Unicamp) and co-author of the article explains that the small ink structures should be able to reach the interstitial tissue – which fills the space between organs – and, from it, detect biomarkers that reflect metabolic changes in the body.
Gustavo Dalkiranis explains that achieving this required a specialized approach to microneedle construction. One of the main challenges was controlling the temperature to properly manipulate the ink, ensuring that “as the droplets landed on the substrate, they would solidify immediately and form the desired structures.”
After an attempt to control the temperature of the printer, the researchers set out to develop their own heating system. It allowed the achievement of an average temperature and a greater control of the geometry of the manufactured structures.
Skin and future applications
In order to verify the efficiency of microneedle production, the scientists designed a testing process using mint leaves. The idea, according to Patrícia, was to simulate the application of the needles in a living system, mimicking a biological tissue. For comparison, flat format biosensors manufactured on the same printer were used. The researcher reports that the signals captured with the microneedle-shaped sensors were significantly “cleaner and more stable than those obtained by flat electrodes, showing the importance of these devices in achieving better information in a future application on human skin”.
“An interesting thing is that the microneedles didn’t go through the mint leaf. They are such sensitive structures that they cause less damage. This is interesting in humans because it is less painful and minimally invasive, and can be used in long-term monitoring applications” – Gustavo Dalkiranis
In addition to promising results, a key advantage of the project is the adaptability of the structures that can be produced. The use of specialized software for microneedle design allows for easy customization. “We were able to produce structures with varying heights, sizes, and shapes. Depending on the need, these adaptations can be made at very low cost,” explains the researcher. The use of different types of ink – such as those containing electrochemically stable metals like gold – can further enhance the quality of biosensor production.
These possibilities for varying microneedle materials and layouts open up new perspectives for the area of personalized medicine and real-time health monitoring. “You will not need to have sample collection precisely because your sensors will be in direct contact with it in real time”, says Patrícia.The potential applications of these small devices also extend to agriculture, supporting efforts such as plant monitoring and pest control.
The article Introducing all-inkjet-printed microneedles for in-vivo biosensing can be read here.
More information: dalkiranis@gmail.com, with Gustavo Dalkiranis, and patyderoco@hotmail.com, with Patrícia Deroco.
*Intern under the guidance of Fabiana Mariz
English version: Nexus Traduções, edited by Denis Pacheco
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A reprodução de matérias e fotografias é livre mediante a citação do Jornal da USP e do autor. No caso dos arquivos de áudio, deverão constar dos créditos a Rádio USP e, em sendo explicitados, os autores. Para uso de arquivos de vídeo, esses créditos deverão mencionar a TV USP e, caso estejam explicitados, os autores. Fotos devem ser creditadas como USP Imagens e o nome do fotógrafo.