Medical Device Link.

Originally Published EMDM March/April 2003

ENGINEERING INSIGHT

A supplier of high-tech ergonomic connectors played a key role in reviving the fortunes of a TCU facing extinction

Connectors supplied by Lemo presented the combination of aesthetic, ergonomic, and compliance features that Geiger Medical Technologies sought for its revamped Thermal Cautery Unit.

It’s often said that you’re only as good as your supplier. John Bottjer, president and owner of Geiger Medical Technologies (Monarch Beach, CA, USA), found out just how much wisdom there is in that statement. His company’s Thermal Cautery Unit (TCU) had not been updated in more than 40 years and a redesign “was a matter of survival for Geiger,” says Bottjer. “The unit had stable sales with little growth potential,” he says, adding that prospects for its long-term survival were grim. The TCU is used by physicians to stop patient bleeding and to destroy lesions by applying high levels of heat through a wire. It sounds simple enough, but Geiger’s existing device had a number of inherent problems. One challenge that Bottjer faced was finding a supplier that could provide a suitable connector within a tight budget and narrow time frame. The US subsidiary of Lemo S.A. (Ecublens, Switzerland) stepped up to the challenge.

Lemo is dedicated to finding solutions through a well-developed design architecture that has been its signature for more than 50 years. By drawing on the company’s resources and applying their expertise, engineers were able to quickly design a simple, easy to connect and disconnect male-female push-pull connector for the cautery unit’s hand piece and receptacle. With this basic foundation in hand, the team could focus on resolving a set of aesthetic, ergonomic, material, and economic issues while meeting the requirements of IEC 601-1.

Aesthetics play an important role in a product that is marketed to physicians for in-patient care and that is visible to the patient during treatment. The previous cautery unit looked outdated and unfriendly, and the design of the hand piece had a negative impact on the patient. The Lemo component has an eye-appealing matte brushed-chrome finish on the outer connector with a polished 
brass-chrome plating lining the inside shell.

Because the physician constantly removes and replaces the hand piece, Geiger also sought to simplify the latching mechanism and improve its ergonomics. The TCU now sports a one-piece Lemo connector (in lieu of two connectors in the previous model), and the split hand-piece cables of the old model have been replaced by a single flexible multiple-conductor cable. To mate the connector, the user simply lines up the keys and clicks them into place. To disengage, he or she pulls on the shell of the male connector to retract the latch ears and pull the keys out of the alignment groove. Lemo connectors are rated to 5000 mating cycles.

Because the TCU has to maintain a desired temperature of 2200°F during tissue contact, Geiger required a high current rating of 10+ A in a connector with only two contacts. Since most products don’t need that much current, connectors typically use small-gauge wires. Lemo, however, was able to use an off-the-shelf connector that required no modifications—one of 55,000 available—with standard contacts for two large-gauge wires able to carry the required current.

Geiger also required a material for the hand piece that would withstand steam sterilization and not corrode after autoclaving or coming into contact with body fluids. Lemo suggested PEEK, a material that many connectors suppliers refrain from using because of its cost. However, PEEK is dimensionally stable across a broad range of temperatures, preventing contacts from moving and shorting out. Easy to mould, PEEK can also be used with a wide range of materials. Because it purchases large quantities of PEEK, Lemo is able to negotiate a reasonable price for the material.
Following the introduction of the new design in 2001, TCU sales skyrocketed 600%. It became the unit of choice with its core audience of dermatologists, surgeons, and veterinarians, while its use expanded into ENT, urology, podiatry, plastic surgery, and international markets. It was also named a winner in the 2002 Medical Design Excellence Awards, a programme sponsored by Canon Communications llc, which also publishes EMDM. Lemo’s contribution to the revamped TCU, according to Bottjer, was one of the major factors in its success.

“Everyone at Lemo—sales, engineering, customer service, and purchasing—was tuned in to our needs from the beginning,” says Bottjer. “The experience exceeded our expectations. The Geiger TCU 150 has realized zero rejected parts from Lemo and zero field failures related to the connector.” 

The Engineering Insight column profiles the use of a technology to improve the effectiveness or safety of a medical device or to optimize its production. If you would like to submit a case study for consideration for this column, please contact the editor by fax, +1 310 4454299, or via e-mail, norbert.sparrow@cancom.com.

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