Designers have used capacitive MEMS microphones in their smartphones, tablets, laptops and digital cameras for almost 20 years. Even though they use silicon processing, capacitive MEMS microphones operate using the same physical principle as condenser-style microphones that have been around for almost 100 years. They measure sound with a capacitor (condenser) made of a flexible diaphragm and a rigid backplate. As multi-membrane capacitive structures, they trap air in between layers, which prevents the sound transducer from moving freely in response to sound pressure, limiting performance.
In contrast, piezoelectric MEMS microphones do not trap a stiff air mass between two plates: Vesper’s diaphragm can move freely in response to sound waves to capture the maximum signal and provide better performance.
The old capacitive MEMS microphones are prone to reliability issues as well. Water, dust, solder flux vapors and other common contaminants can damage them so they lose up to 80% of their signal or stop working altogether. Microphone-matching is more time-consuming because of part-to-part variation, which requires hand-calibration of microphones once they leave the production line.
Vesper uses piezoelectric materials to create the most advanced MEMS microphones on the market. This is a marked shift from capacitive MEMS microphones because piezoelectric microphones operate upon a completely different physical phenomenon – the direct conversion of mechanical sound energy into electrical energy.
Vesper’s piezoelectric design is a single diaphragm that is immune to dust, water, solder flux vapors and other similar environmental contaminants. In fact, Vesper’s has the world’s only MEMS microphones rated at IP57, making them the most waterproof MEMS microphone available. And unlike capacitive MEMS microphones, which require sound-muffling waterproof meshes and protective layers to have a chance against water, our microphones don’t require special packaging, so they preserve acoustic integrity.
In addition, our piezoelectric MEMS microphones utilize a proven, highly reliable and controlled manufacturing process and material, Aluminum Nitride, which major semiconductor companies have used to ship billions of RF filters for mobile phones.
This tight manufacturing process control means that our microphones are remarkably consistent in manufacturing with little variation from microphone to microphone. This improved matching makes our devices more suitable for large arrays.