Oh, patents! WirelessThinklabs One stethoscope (2)

Copyright © Françoise Herrmann

Although the Thinklabs One wireless electronic stethoscopes were released in 2003, seventeen years prior to the COVID 19 pandemic, for all the reasons that make digital auscultation unquestionably superior to conventional auscultation, the devices are now also proven life-saving devices. Life-saving for front-line professionals, working within the context of the hazardous and contagious situations of the COVID 19 pandemic. Situations where professionals are required to wear hazmat suits, or other sorts of personal protection equipment (PPE), such as hoods, face masks and face shields. Indeed, use of a wireless stethoscope, such as the ThinkLabs One, effectively prevents breaking the protection afforded by PPE equipment. Thanks to wireless functionalities, it is also possible to safely auscultate in an isolation room while streaming data to a triage room in real-time, or to auscultate at bedside, while streaming to a professional in another room.  Likewise, it is possible to auscultate in one location, and to stream sounds at a far greater distance within the context of telemedicine.

In fact, ThinkLabs One stethoscopes are marketed as the “smallest and most powerful stethoscopes in the world”, considering the versatility and inclusiveness of their design. Sounds can be amplified 100x, not only to capture and filter heart, lung or blood pressure sounds in unprecedented ways, even through clothes or in chaotic ER environments, but also to enable use for professionals with hearing loss. Auscultatory sounds can even be streamed to programmable Bluetooth-enabled hearing aids. Thinklab One stethoscopes are also powerful enough to be used with disposable protective sleeves for each patient.

Many patents are associated with the Thinklabs One electronic stethoscope. However, the core invention of the Thinklabs One electronic stethoscope —the invention that made it possible to capture, selectively filter, and amplify, body sounds electronically with very little distortion, thereby setting it apart in a class of its own— is the capacitative Electromagnetic Diaphragm (EmD) invention. An invention that directly uses capacitance variation to transduce sounds from the body into electronic signals, without the use of a prior art microphone mounted behind the stethoscope diaphragm, or the use of a prior art piezo-electric crystal sensor connected to the stethoscope diaphragm. This invention is recited in US6498854, titled Transducer for sensing body sounds, a utility patent granted on December 24, 2002.

In the inventor’s own words:  

“I investigated various sensor methods and had many failures, as you'd expect in research. But one method performed beautifully - using capacitive sensing, where the diaphragm acts as one plate of a capacitor. It's really tricky getting such circuits to work well, but I was working in my garage in the middle of winter.” (Clive Leonard Smith, Thinklabs Founder, One designer and inventor)

 The abstract of this invention is included below, together with the patent Figure 8. The patent Figure 8 schematically represents the conductive stethoscope diaphragm 2, in contact with the patient’s body, forming a capacitance with a second plate 3; one or both plates comprising permanently charged material, thus creating an electrical field 80 between them, without relying on DC charging. The diaphragm 2 is mounted to the stethoscope housing, using a mounting clamp 9, made of rubber, to prevent vibrations, from the housing, to reach the surface of the diaphragm 2.

An acoustic-to-electrical transducer for sensing body sounds is disclosed. The transducer comprises a capacitive sensor, whereby a stethoscope diaphragm forms one plate of a capacitor, with the second plate of the capacitor being co-planar to the diaphragm. The capacitance of the two plates varies with the distance between them, said distance being modified by motion of the diaphragm in response to sound pressure. The sensor, circuitry, manufacturing methods and improvements are disclosed. [Abstract US6498854] 

An image of the elegant ThinkLabs One electronic stethoscope is also included above. The Thinklabs One electronic stethoscope looks different from a conventional acoustic stethoscope, with none of the bulky tubing or earpieces. Frequency amplification, corresponding to low pitch heart sounds captured with the bell of a conventional stethoscope, as well as the higher pitch lung sounds captured by the diagram of a conventional stethoscope, is selected using a  dedicated filter button on the perimeter of the Thinklabs One. An Alt (toggle) button enables users to switch filters for the purposes of toggling between their favorite two frequencies. For example, the Alt button is used for toggling between a preferred filter to capture low pitch heart sounds, and a preferred filter to capture high pitch lung sounds. Two additional buttons (plus and minus) on the periphery of the Thinklabs One enable adjustment of the volume. 

Reference

Thinklabs (website)  https://www.thinklabs.com