MICRON DIAMETER FEATURES IN A TINY HEART MONITOR
6/4/13 An exciting new technology was unveiled by Stanford University earlier this month. They created a tiny heart monitor that uses a few micron diameter pyramid bumps (the size of a human red blood cell) similar to those seen here.
Engineers at Stanford University were able to combine layers of flexible material into pressure sensors to make a wearable heart monitor that is thinner than a dollar bill! Without the use of micro sized components this monitor would not have been possible. Read more about this in the below article from the Stanford Report My 14, 2013:
Article:
Stanford engineers monitor heart health using paper-thin flexible ‘skin’
Engineers combine layers of flexible materials into pressure sensors to create a wearable heart monitor thinner than a dollar bill. The skin-like device could one day provide doctors with a safer way to check the condition of a patient’s heart.
Most of us don’t ponder our pulses outside of the gym. But doctors use the human pulse as a diagnostic tool to monitor heart health.
Zhenan Bao, a professor of chemical engineering at Stanford, has developed a heart monitor thinner than a dollar bill and no wider than a postage stamp. The flexible skin-like monitor, worn under an adhesive bandage on the wrist, is sensitive enough to help doctors detect stiff arteries and cardiovascular problems.
The devices could one day be used to continuously track heart health and provide doctors a safer method of measuring a key vital sign for newborn and other high-risk surgery patients.
“The pulse is related to the condition of the artery and the condition of the heart,” said Bao, whose lab develops artificial skin-like materials. “The better the sensor, the better doctors can catch problems before they develop.”
Your pulse
To find your pulse, press your index and middle finger into the underside of your opposite wrist. You should feel the steady rhythm of your heart as it pumps blood through your veins.
Each beat you feel is actually made up of two distinct peaks, even though you can’t tell them apart with just your fingers. The first, larger peak is from your heart pumping out blood. Shortly after a heartbeat, your lower body sends a reflecting wave back to your artery system, creating a smaller second peak.
The relative sizes of these two peaks can be used by medical experts to measure your heart’s health.
“You can use the ratio of the two peaks to determine the stiffness of the artery, for example,” said Gregor Schwartz, a post-doctoral fellow and a physicist for the project. “If there is a change in the heart’s condition, the wave pattern will change. Fortunately, when I tested this on myself, my heart looked fine.”
To make the heart monitor both sensitive and small, Bao’s team uses a thin middle layer of rubber covered with tiny pyramid bumps. Each mold-made pyramid is only a few microns across – smaller than a human red blood cell.
When pressure is put on the device, the pyramids deform slightly, changing the size of the gap between the two halves of the device. This change in separation causes a measurable change in the electromagnetic field and the current flow in the device.
The more pressure placed on the monitor, the more the pyramids deform and the larger the change in the electromagnetic field. Using many of these sensors on a prosthetic limb could act like an electronic skin, creating an artificial sense of touch.
When the sensor is placed on someone’s wrist using an adhesive bandage, the sensor can measure that person’s pulse wave as it reverberates through the body.
The device is so sensitive that it can detect more than just the two peaks of a pulse wave. When engineers looked at the wave drawn by their device, they noticed small bumps in the tail of the pulse wave invisible to conventional sensors. Bao said she believes these fluctuations could potentially be used for more detailed diagnostics in the future.
Blood pressure and babies
Doctors already use similar, albeit much bulkier, sensors to keep track of a patient’s heart health during surgery or when taking a new medication. But in the future Bao’s device could help keep track of another vital sign.
“In theory, this kind of sensor can be used to measure blood pressure,” said Schwartz. “Once you have it calibrated, you can use the signal of your pulse to calculate your blood pressure.”
This non-invasive method of monitoring heart health could replace devices inserted directly into an artery, called intravascular catheters. These catheters create a high risk of infection, making them impractical for newborns and high-risk patients. Thus, an external monitor like Bao’s could provide doctors a safer way to gather information about the heart, especially during infant surgeries.
Bao’s team is working with other Stanford researchers to make the device completely wireless. Using wireless communication, doctors could receive a patient’s minute-by-minute heart status via cell phone, all thanks to a device as thick as a human hair.
“For some patients with a potential heart disease, wearing a bandage would allow them to constantly measure their heart’s condition,” Bao said. “This could be done without interfering with their daily life at all, since it really just requires wearing a small bandage.”
The team published its work in the May 12 edition of Nature Communications. The team’s research is supported by funding from the National Science Foundation and the Air Force Office of Scientific Research.
MICRO MACHINING = PARTS IN HAND QUICKLY
5/28/13 Micro machining encompasses R&D for products, high production growth and mature products. One of the fastest ways to get micro parts in our customer’s hands has traditionally been micro machining.
Many applications can be justified to spend capital on tooling up for micro molding, however, if the design has been made iteration-friendly (steel safe, inserted for areas thought to be changing prior to design freeze) then it may be a perfect candidate for micro machining.
Some of the components we have worked on in these categories include resorbable polymer implants, ophthalmic implants and lenses, suture devices, implantable clips, inkjet components and hearing aid components. We are capable of making a wall thickness down to 0.001″, surface features down to 0.0001″ and tip radius for sharp points on needles down to < 0.0007″.
Here are some benefits to Micro Machining over other Micro Processes:
• Fast Parts in Hand to show feasibility
• Capital Cost Effectiveness in both low and high volume
• Features to 3 microns
• Surface finish to < 8 Ra
• Use of final material from prototype through production
Not all materials are friendly to micro machining, such as: some polymers, heat sensitive materials, and drug-induced materials. The shear stresses in which micro machining occurs can render a material degradable, physically weak, and/or unfit for sterilization in some cases.
PARTNERSHIP IN DRUG DELIVERY IN BOSTON
05/20/13 Our organization, MES, is located near Boston MA and we always have our eyes open looking for partnerships in drug delivery. Drug delivery and medical devices are requiring new products that create tinier, less invasive, fluid-induced, and/or space saving micro devices. The tiniest parts in an assembly are the enabling components to the device and also the components most likely to pose manufacturing, handling, and assembly challenges. These products require customized integrated and automated solutions to ensure their success out of the gate. We believe choosing both highly iterative and scalable micro manufacturing and assembly processes will aid in robust and fast to market drug delivery devices. We have the knowledge and experience to work with companies that need micro engineering expertise in this fast moving field. You can read more about this subject in an article we wrote for the Medical Design Magazine. Please click on this link to see the article in one of our past blogs.
MICRO MACHINING
5/15/13 Micro Engineering Solution’s expertise in the micro manufacturing field enables us to be successful with any scale project, from initial concept to high volume manufacturing. Key areas include micro machining, micro molding and micro assembly.
One of the fastest ways to get micro parts in our customer’s hands has traditionally been micro machining. Many applications can be justified to spend capital on tooling up for micro molding, however, if the design has been made iteration-friendly (steel safe, inserted for areas thought to be changing prior to design freeze) then it may be a perfect candidate for micro machining.
Benefits to Micro Machining over other Micro Processes:
• Fast Parts in Hand to show feasibility
• Capital Cost Effectiveness in both low and high volume
• Features to 3 microns
• Surface finish to < 8 Ra
• Use of final material from prototype through production
Not all materials are friendly to micro machining, such as: some polymers, heat sensitive materials, and drug-induced materials. The shear stresses in which micro machining occurs can render a material degradable, physically weak, and/or unfit for sterilization in some cases.
You can see samples of the parts we have been involved with on our Micro Machining page of our website.
BIO-RESORBABLE POLYMER MICRO MOLDING PRESENTATION IN MASSACHUSETTS 5/14/13
5/14/13 Bio-Resorbable Polymer Micro Molding Presentation in Massachusetts 5/14/13. Drug Delivery Using Slow and Controlled Release Polymers.
Reservations required, please eamil John Lamont with SME at JLamont.hsmg@comcast.net.
See you there!
~ Donna Bibber
Dust Speck Sized Micro Molded Parts and Features are true Disruptive Technology in Implants and Drug Delivery Devices now and into the future
MICRO TOOLING CONSIDERATIONS
5/1/13 Micro tooling enables micro molding, and machining is extremely critical. Since we don’t currently have a “micro” industry standard to go by, we had to create a rough ASTM standard when we make tooling. Example: the industry standard uses an 8” tensile bar, which doesn’t help us in the MICRO world so we had to create a 0.00001” x 0.00002”. In this example we had parts in molds that have 0.00002” gates, with that being a very small gate you end up shearing the material that is going through that small gate. Most conventional sized tools are 0.0002” gate, so you are shearing the material much more than it’s used to, therefore we have to determine what we did with that extra heat/extra shear when it went through an injection mold. We had to make the very small tensile bars to be able to test that polymer to see what happens to the part when subjected to very high shear forces.
Conventional tool making practices, like CNC-EDM-wire EDM, are using extremely small wires (about 0.001”). We have made electrodes for extremely small machined components to be used in the mold.
Unconventional tool making practices are needed in the MICRO world and they include:
- Machining techniques
- Venting
- Core pins 0.0029”
- Ejector pins 0.0049”
- Multi-component micro molding
Acceptable tolerances in conventional sized tools are unacceptable in the micro world. For example: when you have a 0.001” wall thickness and your tool parting line is .02” in Y and 0.03” in X. The 0.03” is 30% of the wall thickness. So what would conventionally happen is when you inject the material down the fat side it will fill very easily but it won’t fill the thin side. It has to be balance filled to fill something using these extremely small parts. What needs to be done in this example is we had to split the 0.03” and 0.02” offset in tooling to create a 0.01” error to be able to fill that part uniformly.
CURRENT MICRO TOOLING METHODS
Top-down methods Bottom-up methods
(removing steel to create the part/tool)
Laser machining genetic code
EDM_WEDM complexity theory
Ultrasonic machining self assembly
Ion machining biological cell
CNC machining proteins
Chemical milling DNA and RNA
Photochemical machining LIGA
Elecrochemical machining