Thinklabs DS32a – Patent No.: US 6,498,854 B1 Are you familiar with the patent? Yes, it’s patent product is the stethoscope DS32a manufactured by Thinklabs. What’s your experience with the product? Based on the feedback we collected from physicians, it’s very user friendly. Here from the images of the product, you see the chestpiece that will directly contact the body surface and the visual indicator to give physicians control of the device and also allows recording of the body sound for an alternative interpretation. Because this product is based on capacitive sensors, it can overcome the shortcomings of traditional stethoscope. 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Simulation Presentation: Obviousnes Patent No. 6498854 Patent ‘854, Claim 13 An electronic stethoscope including an acoustic-to-electrical transducer for detecting body sounds, the transducer comprising: a stethoscope diaphragm having an electrically conductive surface, the diaphragm being mounted in a stethoscope chestpiece such that the diaphragm can contact the body for body sound detection and vibrate in response to body sounds; a fixed conductive plate substantially parallel to the diaphragm, mounted within the chestpiece, the conductive plate being positioned at a distance about or exceeding 0.5 mm from the diaphragm, the diaphragm conductive surface and fixed conductive plate forming two plates of a capacitor and connected in the form of an electrical capacitance to electrical circuitry; a capacitance-to-electrical signal conversion means to convert diaphragm-plate capacitance changes due to body sound vibrations to electrical signals; the stethoscope further comprising signal amplification means and at least one electrical-to-acoustic transducer connected to signal amplification means, to reproduce body sounds as detected by said transducer. 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Patent ‘854, Claim 13 a stethoscope diaphragm having an electrically conductive surface, the diaphragm being mounted in a stethoscope chestpiece such that the diaphragm can contact the body for body sound detection and vibrate in response to body sounds; 4 Movable, Flexible Diaphragm Electrically Conductive Surface of Diaphragm Electric Field Electrically Conductive Plate Attachment Means to Mount to Housing 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Traditional acoustic stethoscope ear pieces tubing chest piece 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Microphone based stethoscope Acoustic to electronic signal US Pat. No. 6002777 How does other electronic stethoscope solve the problem? In order for the capacitor to function, a voltage around 400V has to be maintained across the gap, which prevents the direct contact of the diaphragm to the human body. And unlike the microphone with the casing, the body sound is not a very strong acoustic incoming signal, which rules out the possibility of having the casing like in the microphone device. So what we have to do is to have a second insulating diaphragm in front of the capacitor for protection. This is potentially problematic because the additional gap admits more ambient noise and would compromise the quality of the body sound detection. Insulation layer 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Piezoelectric stethoscope Are you familiar with the traditional stethoscope? Yes, it’s basically a chest piece that touches the body, the sound passes through the tubing to the ear piece worn by the doctors. Can you say something about how the traditional stethoscope work? If we concentrate on the chest piece, you’ll see a small piece of crystal behind the diaphragm. The crystal deforms upon pressure and generates different electric response, which is basically what the doctors are hearing through the ear piece. It’s less than ideal because the signal is generated by crystal deformation. Without going to details, it suffices to say, and many physicians would agree, that the detection of body sound is hard. non-linear conversion distortion different tones 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Simulation Presentation: Obviousnes Patent No. 6498854 What is a capacitor? Mentioned capacitive sensor. Say something about that. Capacitor, from its name, you know that this electric component has some kind of capacity, like a water reservoir. So what are we storing? We have a pair of conductors separated by a dielectric material in the middle. By this design, we can store electric energy by separating opposite charges to the two plates. And the take home message is that the capacitance depends on the separation. Larger the separation between the plates, smaller the capacitance. 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Prior art: capacitive microphone How can a capacitor then be used in sensor? A capacitive microphone uses the same mechanism as part of the device that converts sound wave to electronic signals. As you see here, we have a capacitor device inside the casing of the microphone. If we just focus on this part of the microphone, we see that as sound wave comes in, the diaphragm, which is one plate of the capacitor, will vibrate accordingly. This effectively change the gap size of the capacitor. And as you recall from the previous slide, the change in the gap size will change the capacitance. As you can see here from the animation, sound wave comes in, compress the diaphragm, reduce the gap, change the capacitance, we get the signal! 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Simulation Presentation: Obviousnes Patent No. 6498854 Prior art: microphone 400 V ! So what happens if we just take the microphone design to detect body sound? Well, electric shock is what you will get. Let’s get back to the picture of the capacitor. As you recall, I said that a capacitor is like a reservoir for energy storage. However, if you don’t build a dam to contain the water in the reservoir, you not only cannot store hydraulic energy, but you still end up with flood. Similarly, if we don’t impose a voltage big enough to hold the charges to the plates, the attraction between the positive and negative charges will make them tend to get mixed together, thus destroy the separation of the charges for energy storage. For the capacitor to function, a voltage is definitely needed. But as we have said, the voltage required is around 400V, much higher the 110V from the power outlet. If 110V is already enough to give people a shock, you certainly don’t want to have a 400V close to the patient without any protection 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Simulation Presentation: Obviousnes Patent No. 6498854 Thinklabs DS32a Acoustic to electronic signal How does the patented design solve the problem? In order to solve the intrinsic problem of ambient noise in the traditional stethoscope, the patented design actually collapse insulating diaphragm with the front layer of the capacitor. This way we achieve several goals at the same time. First is of course to reduce the ambient noise by eliminating the second gap. The improvement of the body sound quality has actually been verified by many practicing physicians, who compared this product with the traditional stethoscope they used to use. Second, even though we don’t have a second diaphragm, the insulating layer is still there to protect the body from the high voltage across the gap, which I am sure all the patients will really appreciate. And finally, because we only need a single diaphragm, the cost of manufacturing these stethoscope with better sound detection is reduced, which is part of the reason of the commercial success of the product. Benefit of the single diaphragm Reduction of noise Protection from electronic shock Lower manufacturing cost 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Tactile sensor vs Physical touch vs acoustic wave Finger Flexible, Insulating Layer “X-Y Matrix” X-trace Y-trace Is there single diaphragm device? Yes. Unlike the capacitive sensor, tactile sensor admits the possibility of using a single diaphragm. Here the insulating layer 45 and the flexible x-y matrix layer 25 are collapsed. Unlike the device based on microphone, the pressure is generated by physical touch on the touch screen other than acoustic wave. The contacting frequency of the touch screen technology is mostly upper bounded by a few Hz. On the other hand, sound frequency detectable by human ear is between 20 to 20k Hz, much larger than the range of tactile sensor. Now you have to remember, in signal processing, the techniques employed to analyze low frequency input vs high frequency input are definitely not the same. In addition, compared with the physical touch, acoustic wave picked up by the stethoscope is a much weaker signal in terms of intensity. And because acoustic wave may come from any direction, the surface that actually can receive the incoming signal is undefined, unlike the touch screen case. So sound detection by the stethoscope is a much harder problem than the tactile sensor. Even though technology based on tactile sensor is very popular these days in consumer electronics, such as the iphone, at the time of the invention of our patent, tactile sensor was still in its infancy in terms of development and the surface pressure sensors have not been fully developed for everyday use until recent years Physical touch vs acoustic wave Different intensity of signal Different frequency range vs 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854

Microphone + Tactile sensor = ? Not obvious when combining microphone and tactile sensor. You may find the fundamental science related, but when one is adapting the microphone and the tactile sensor to the stethoscope, a person with ordinary skill of art is facing a daunting task of testing various material for the diaphragm for adequate vibration, dielectric material for the correct capacitance change, and not to mention material for biocompatibility to the human body and cost effective material to reduce the cost of this commercially successful product. NO! 4/14/2019 Simulation Presentation: Obviousnes Patent No. 6498854