While still in the development stage, acoustic data link (ADL) technology is potentially a game changer for sectors where data communication is needed to penetrate secure metallic containers.
The technology from TDK Electronics bolsters the effectiveness and efficiency of systems — from industrial and food to healthcare and defense — with sensors monitoring systems 24/7 to identify whether they are operating in optimal parameters or not.
The sensors used in the ADL technology are enablers of predictive maintenance to improve performance, reduce downtime and increase safety of whatever resides inside these secure metallic containers.
Faraday cages
Closed metallic structures, such as Faraday cages, are structures that block electromagnetic signals and prevent conventional wireless data transmission from going in or out.
Faraday cages shield the contents inside a metallic structure from unwanted disruptions like:
- Electric fields
- Electromagnetic radiation — radio waves, microwaves
- Electrostatic discharges
- Electromagnetic pulses (EMP)
These structures are important to protect sensitive equipment, data and even people from these disruptions. However, while the whole point of a Faraday cage is to block communication, there are situations where you still want to communicate with it inside such as:
- Testing a device inside the cage — like a smartphone or router
- Scientific and medical equipment found in shielded rooms (EEG or MRI)
- Process automation inside a cleanroom
- Food production
- Command systems or encrypted communication centers
- Industrial equipment monitoring
What is ADL?
One way to communicate inside a metallic structure is through TDK’s acoustic data link (ADL) technology.
ADL converts electric signals into a directional mechanical vibration resulting in an acoustic wave that can penetrate metals. ADL uses two opposed piezo transducers that create a bidirectional acoustic data channel. Each transducer acts as sender and receiver at the same time.
“The list of industries that use sealed metal reactors, pressure vessels, tanks, vats and other enclosures extends well beyond the food industry,” said Volker Wischnat, TDK’s customer development lead. “Any industry that could improve process control by embedding a sensor into their processing chambers could benefit.”
Specifically, TDK is gaining interest from industries that are adopting pipe-in-pipe constructions. Other interest comes from biotechnology, chemicals and petrochemicals, Wischnat said. ADL technology makes it easier to monitor electronics inside.
How it works
TDK’s ADL technology consists of two piezo transducers, each connected to either side of a homogeneous metal plate. These links convert electric signals into a directed mechanical vibration which in turn excites acoustic waves on the material surface.
“In prototypes, our engineers have demonstrated simultaneous power supply and data acquisition for more than ten different sensors monitoring temperature, pressure, humidity, and acceleration,” Wischnat said. “The solution works over a temperature range from -40° C to +105° C.”
The ADL channel can support up to 2 MHz bandwidth, which can transmit a full data rate of 11 kBit/s that NFC can support. It also can support data transfer rates in the megabits-per-second range.
Wischnat said that indications also suggest the technology supports a power transfer of up to 100 mW.
The next steps
The piezo technology underlying ADL could potentially be used beyond data transmission.
According to Wischnat, ADL already used its piezo elements to convert mechanical movement into energy that is enough to operate multiple sensors without additional power sources.
The technology could be integrated into electronics for a wide variety of purposes like obstacle and presence detection as well as liquid level sensing in hard environmental conditions. Haptics is another area seeing innovation from piezo transducers in physical force feedback. There have also been some developments in customized haptic feedback for touchscreens using the piezo technology.
