Transducers (probes)

Because of the very low manufacturing costs we can deliver transducers at a reasonable retail price. A standard 10MHz (100ns pulse length) transducer comprising a sound emitting element mounted in a stainless steel housing and a BNC connector cost 160,- Euro. The element is 5mm in diameter; the steel housing is 10mm in diameter and 30mm long.
  

As a result of our biometric project a new class of ultrasound transducers has been created, for which a patent application has been submitted. Unlike classical designs, our transducers do not require damping and do not use bonded elements.

Fig. 1 shows a transducer element with housing. We can deliver the transducers in any type of housing or without it. Fig 2 shows a pulse generated by our transducer (a hydrophone made of PVDF film has been used for the measurement). The signal received in the transceiver mode is depended on the transducer used. We have optimized (and can deliver) three types of transducers, with medium frequencies of about 21, 11 and 5MHz (and pulse length of about 40, 100 and 200ns). The signals produced by them in send&receive mode are shown on the pictures 3, 4 and 5. The difference between the two signals results from the fact that our transducer works differently as a transmitter and as a receiver.
  

Fig 2.

Fig 3.

Fig 4.

Fig 5.
  

Bandwidth: 3-25 MHz (maximal 3dB bandwidth for a single transducer, different frequency ranges are also available). 

Minimal length of a pulse: 20ns (40ns if the same transducer is used for both generating and receiving the pulse). 

Pulse amplitude is around two times higher than for classical, attenuated piezoceramic transducers. 

Sensitivity is comparable to classical transducers (it is likely to be improved in the future). 

Minimal diameter: ca 1mm 

Maximal diameter: limited only by the available ceramics 

Minimal thickness of the transducer: ca 1.3 mm, standard width is 2mm. The element is the actual transducer, it can be placed in a case or mounted to another object. 

Temperature range: Dependent upon the type of ceramics used (it is possible to use special types of ceramics; typically standard ceramics gives satisfactory results) the transducer can be designed in such a way that the only limiting factor for the temperature range is the ceramics used. Our transducers will not get permanently damaged even if their temperature raises above the Curie point. Once they cool down they become operational again, prided that our pulse generator is used. We have prooved construction, that can work continuosly at 200°C. 

Maximal supply voltage: pulses of up to 700V peak value. Any type of pulse generator can be used. 

Electrical impedance is equivalent to the impedance of a capacitor with comparable capacitance (ca 1.5 nF for the transducer with the diameter of 4 mm). The impedance module is around 20 Ohm for 10 MHz. 

Tolerance of the pulse shape. Assuming the same ceramics, differences between different transducers are less than 5 % of the amplitude.