The surface properties of a material are especially important in the case of implantable biomaterials, since it is the surface of the material that first contacts the body. The properties of the surface defines how the materials degrades, if blood coagulates on contact, and how cells will populate the material. By modifying the surface properties one can modulate the way implants are perceived by the body. This can be done by absorbing polymers or proteins for instance. But characterizing these surface modifications can be challenging. For instance how can we weigh such extremely small quantities that are adsorbed to these surfaces? Typically, these coatings weigh in the nano grams per cm2 range.
Luckily, a number of surface sensitive techniques can help detect small changes at the surface of materials. One we have used in particular is the Quartz Crystal Microbalance. A QCM is composed of a quartz crystal sandwiched by two gold electrodes. The quartz crystals vibrates when stimulated by an electric field and the vibration frequency changes if a force is exerted on the crystal. A force you say? Like the force exerted by the weight of a few protein molecules? Yes!
There you have it. By detecting small changes in the vibration, one can estimate the amount of materials deposited on the surface, which opens the door to our better understanding of many phenomenon at the interface.
Several manufacturer now commercialize QCMs. However, most cost in the tens of thousands of euros, if not hundreds of thousands. But the Italian company Novaetech recently release a low cost Open Source QCM. The design is totally open source and highly modular. For instance the case is 3D printed, which allows users to play around with its design relatively easily.
The Open Source QCM project allows anyone to produce or purchase a basic QCM module for little money, which will surely help to democratize this instrument in research labs. The mounted and tested version of the OpenQCM will cost you only 499€. From I have seen, it seems well designed and relatively easy to use since it connects to computer via usb and comes with the software to run it directly out of the box.
We have not tried it ourselves yet, but it is just a matter of time. Would love feedback about what you think of it!