What are “Nanomechanical Sensors”?
- Nanomechanical sensors detect target substances mechanically.
- It means, nanomechanical sensors respond to the “volume” or “mass” change induced by the adsorption of target substances.
- There are no substances which do not have volume and mass, thus nanomechanical sensors can detect almost any kind of substance.
- Owing to such intrinsic versatility, nanomechanical sensors are expected as a new sensor platform for various applications including medical, security, and environmental applications.
Why “Nano” mechanical sensors?
- You can find lots of “nano” in this kind of sensor, for example, the mechanical motion (deformation, deflection, etc…) of nanomechanical sensors is typically in the range of nano-meter.
- Technically, it is impossible to understand or operate nanomechanical sensors without “nanotechnology” in terms of fabrication, read-out, and analysis.
- It would be better to notice that the size of sensing element is not necessarily in nano-meter range. Rather, it is usually in micro-meter range.
How do “Nanomechanical Sensors” look like?
- The most representative structure is a “cantilever“.
The optimized “Nanomechanical Sensor”
- Recently, we made a comprehensive optimization of a nanomechanical sensor to fulfill the requirements for practical applications such as sensitivity, stability, size, cost, etc.
- Then, we successfully developed a Nanomechanical Membrane-type Surface Stress Sensor (MSS) shown below:
The MSS consists of a thin adsorbate membrane suspended by four constricted sensing bridges along the rotation axes of silicon crystal, composing a full Wheatstone bridge for the electric read-out.
The sensitivity of MSS reached a similar range with that of optically read-out cantilevers (limit of detection ~0.1 mN/m).