Based on the physical properties being measured, microsensors can be classified into chemical microsensors, biological microsensors, physical microsensors, etc.
I. Ion Sensors – Chemical Type
An ion sensor is a sensor that converts the activity of ions in a solution into an electrical signal. The basic principle is that an ion-recognizing material fixed on a sensitive membrane selectively binds to the sensed ions, causing a change in membrane potential or voltage, thus achieving detection. Ion sensors are widely used in industries such as chemistry, medicine, food, and bioengineering.
II. Gene Sensors – Biological Type
Gene sensors work by hybridizing a single-stranded deoxyribonucleic acid (DNA) molecule (also known as an ssDNA probe) with a known nucleotide sequence immobilized on the surface of a receptor with another complementary ssDNA molecule (also known as target DNA) to form double-stranded DNA (dsDNA). A transducer converts the changes resulting from the hybridization process or outcome into physical signals such as electricity, light, and sound. By analyzing these response signals, information about the relevant gene is provided. Gene sensors are also called DNA sensors.
III. Surface Acoustic Wave Sensors – Physical Type
Surface acoustic wave (SAW) sensors are devices that use surface acoustic wave technology and microelectromechanical systems (MEMS) technology to convert changes in various non-electrical quantities, such as pressure, temperature, flow rate, magnetic field strength, acceleration, and angular velocity, into changes in the oscillation frequency of a surface acoustic wave vibrator.
