Ultrasound and piezoelectrics are used in a myriad of applications in medical handpieces from imaging diagnosis to surgical cutting to regenerative bone healing and other therapeutic modalities. Constantine Technologies has experience dealing with safety concerns and the sometimes harsh environments faced in medical handpiece engineering. Only a few capabilities are listed on this page.

Phacoemulsification

Phacoemulsification is the current standard for modern cataract surgery. Using an ultrasonic handpiece, a surgeon emulsifies, or liquefies, the offending lens. The remains are removed by aspiration and an artificial lens is inserted. The surgery is usually performed as an outpatient procedure and vision is often restored within a few hours.

Dean was an integral contributor to the piezoelectric design of some of the first phacoemulsifying handpieces.

Design considerations for a phacoemulsifying handpiece include:

  • As is common for most medical handpieces, phacoemulsifiers need to be designed to withstand the rigors of sterilization. It has been said, “Any fool can design a transducer, but it takes a genius to keep the water out.”
  • Because of the delicate environment it is important to have consistent electrical and acoustic matching to ensure that delivered power is within safety limits.
  • In addition to good impedance matching, transducer designers must be considerate of tip displacement so the effected area can be precisely controlled.
  • Depending on the skill and speed of the surgeon, heat dissipation can become a concern. Design should allow for a broad range of skill levels.
Phacoemulsifier handpieces

Figure 1: Phacoemulsifier handpieces

Lithotripsy

Extracorporeal Shock Wave Lithotripsy (ESWL) is the standard form of treatment for calculosis: the common kidney stone. The non-invasive treatment is performed with an ultrasonic array. The short-length, pulsed, ultrasonic waves break the kidney stone apart for a more comfortable passage through the urinary tract.

Other clinical situations require an invasive form of transcorporeal lithotripsy. Handpieces used for this procedure make direct physical contact with the kidney stone. After breaking the stone apart the remantants are aspirated.

Design considerations for a lithotriptor ultrasonic handpiece include:

  • Depending on the application various degrees of precaution need to be taken when considering the sterilization process.
  • ESWL arrays can be designed to include diagnostic imaging along with therapeutic treatment. This includes careful consideration of beam formation and transducer dimensions as well as pulse sequences.
  • Transcorporeal lithotriptors must have careful geometric design to allow the operator to have a full range of access, but not interfere with the resonance mode of the active rod.
Lithotriptor handpiece

Figure 2: Lithotriptor handpiece

Ultrasonic Liposuction

Ultrasonic Assisted Liposuction (UAL) and eXternal Ultrasonic Assisted Liposuction (XUAL) are methods of fat emulsification (liquefication) used in liposuction procedures. Ultrasonic vibrations break fat cells which are subsequently removed from the body.

Design considerations for a UAL handpiece include:

  • With liposuction handpiece design it has been traditionally important to consider how ultrasonic therapy will compete against other treatment modalities.
  • Common to handpiece design, it can be fundamental to consider the data required to pass FDA regulations early in the design process.

Dental Handpieces

Piezoelectric actuation is used for a broad variety purposes in dentistry from drilling to cleaning and even toothbrushing. The design considerations for dental handpieces vary widely depending on the application. Safety is always an important concern, and as with many medical handpieces, the rigors of autoclaving are often a concern. CTL has experience overcoming these challenges.