Tag Archives: Nanshu Lu

Wearable device to monitor and control diabetes is based on graphene

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The research comes from Korea’s Institute of Basic Science and was announced in a March 22, 2016 news article by Lee Chi-dong for Yonhap News Agency,

A team of South Korean scientists announced Tuesday [March 22, 2016] that they have developed a wearable device, based on nanotechnology, for more convenient diabetes monitoring and therapy.

The graphene-using “smart patch” has improved the accuracy of blood sugar level measurements as it checks not only glucose in sweat but also temperature and acidity, according to the Institute for Basic Science (IBS) located in Daejeon, some 160 kilometers south of Seoul.

Existing smart patches gauge blood sugar merely in sweat.

Google is working on “smart contact lens” with an ultra-tiny super sensitive glucose sensor for tear fluid. Its accuracy remains a question amid concerns about adverse effects on eye health.

A March 21, 2016 IBS press release on EurekAlert provides more details about the work,

A scientific team from the Center for Nanoparticle Research at IBS has created a wearable GP [graphene]-based patch that allows accurate diabetes monitoring and feedback therapy by using human sweat. The researchers improved the device’s detecting capabilities by integrating electrochemically active and soft functional materials on the hybrid of gold-doped graphene and a serpentine-shape gold mesh. The device’s pH and temperature monitoring functions enable systematic corrections of sweat glucose measurements as the enzyme-based glucose sensor is affected by pH (blood acidity levels) and temperature.

Diabetes and regulating glucose levels

Insulin is produced in the pancreas and regulates the use of glucose, maintaining a balance in blood sugar levels. Diabetes causes an imbalance: insufficient amounts of insulin results in high blood glucose levels, known as hyperglycemia. Type 2 diabetes is the most common form of diabetes with no known cure. It affects some 3 million Koreans with the figure increasing due to dietary patterns and an aging society. The current treatments available to diabetics are painful, inconvenient and costly; regular visits to a doctor and home testing kits are needed to record glucose levels. Patients also have to inject uncomfortable insulin shots to regulate glucose levels. There is a significant need for non-invasive, painless, and stress-free monitoring of important markers of diabetes using multifunctional wearable devices. The IBS device facilitates this and thereby reduces the lengthy and expensive cycles of visiting doctors and pharmacies.

Components of the graphene-based wearable device

KIM Dae-Hyeong, a scientist from the Center for Nanoparticle Research, describes the vast array of components: “Our wearable GP-based device is capable of not only sweat-based glucose and pH monitoring but also controlled transcutaneous drug delivery through temperature-responsive microneedles. Precise measurement of sweat glucose concentrations are used to estimate the levels of glucose in the blood of a patient. The device retains its original sensitivity after multiple uses, thereby allowing for multiple treatments. The connection of the device to a portable/ wireless power supply and data transmission unit enables the point-of-care treatment of diabetes.” The professor went on to describe how the device works, “The patch is applied to the skin where sweat-based glucose monitoring begins on sweat generation. The humidity sensor monitors the increase in relative humidity (RH). It takes an average of 15 minutes for the sweat-uptake layer of the patch to collect sweat and reach a RH over 80% at which time glucose and pH measurements are initiated.”

Merits of the device and drug administration

The device shows dramatic advances over current treatment methods by allowing non-invasive treatments. During the team’s research, two healthy males participated in tests to demonstrate the sweat-based glucose sensing of the device. Glucose and pH levels of both subjects were recorded; a statistical analysis confirmed the reliable correlation between sweat glucose data from the diabetes patch and those from commercial glucose tests. If abnormally high levels of glucose are detected, a drug is released into a patient’s bloodstream via drug loaded microneedles. The malleable, semi-transparent skin-like appearance of the GP device provides easy and comfortable contact with human skin, allowing the sensors to remain unaffected by any skin deformations. This enables stable sensing and efficient drug delivery.

The scientific team also demonstrated the therapeutic effects by experimenting on diabetic (db/db) mice. Treatment began by applying the device near the abdomen of the db mouse. Microneedles pierced the skin of the mouse and released Metformin, an insulin regulating drug, into the bloodstream. The group treated with microneedles showed a significant suppression of blood glucose concentrations with respect to control groups. “One can easily replace the used microneedles with new ones. Treatment with Metformin through the skin is more efficient than that through the digestive system because the drug is directly introduced into metabolic circulation through the skin,” commented KIM Dae-Hyeong. He went on: “These advances using nanomaterials and devices provide new opportunities for the treatment of chronic diseases like diabetes.”

The researchers have made an image illustrating their work available,

Caption: Optical image of the GP-hybrid electrochemical device array on the human skin Credit: IBS

Caption: Optical image of the GP-hybrid electrochemical device array on the human skin Credit: IBS

Here’s a link to and a citation for the paper,

A graphene-based electrochemical device with thermoresponsive microneedles for diabetes monitoring and therapy by Hyunjae Lee, Tae Kyu Choi, Young Bum Lee, Hye Rim Cho, Roozbeh Ghaffari, Liu Wang, Hyung Jin Choi, Taek Dong Chung, Nanshu Lu, Taeghwan Hyeon, Seung Hong Choi, & Dae-Hyeong Kim. Nature Nanotechnology (2016) doi:10.1038/nnano.2016.38 Published online 21 March 2016

This paper is behind a paywall.

An easier and cheaper way to make: wearable and disposable medical tattoolike patches

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A Sept. 29, 2015 news item on ScienceDaily features an electronic health patch that’s cheaper and easier to make,

A team of researchers has invented a method for producing inexpensive and high-performing wearable patches that can continuously monitor the body’s vital signs for human health and performance tracking. The researchers believe their new method is compatible with roll-to-roll manufacturing.

The researchers have provided a photograph of a prototype patch,

Assitant professor Nanshu Lu and her team have developed a faster, inexpensive method for making epidermal electronics. Cockrell School of Engineering

Assitant professor Nanshu Lu and her team have developed a faster, inexpensive method for making epidermal electronics. Cockrell School of Engineering

A University of Texas at Austin Sept. 29, 2015 news release (also on EurekAlert), which originated the news item, provides more details,

Led by Assistant Professor Nanshu Lu, the team’s manufacturing method aims to construct disposable tattoo-like health monitoring patches for the mass production of epidermal electronics, a popular technology that Lu helped develop in 2011.

The team’s breakthrough is a repeatable “cut-and-paste” method that cuts manufacturing time from several days to only 20 minutes. The researchers believe their new method is compatible with roll-to-roll manufacturing — an existing method for creating devices in bulk using a roll of flexible plastic and a processing machine.

Reliable, ultrathin wearable electronic devices that stick to the skin like a temporary tattoo are a relatively new innovation. These devices have the ability to pick up and transmit the human body’s vital signals, tracking heart rate, hydration level, muscle movement, temperature and brain activity.

Although it is a promising invention, a lengthy, tedious and costly production process has until now hampered these wearables’ potential.

“One of the most attractive aspects of epidermal electronics is their ability to be disposable,” Lu said. “If you can make them inexpensively, say for $1, then more people will be able to use them more frequently. This will open the door for a number of mobile medical applications and beyond.”

The UT Austin method is the first dry and portable process for producing these electronics, which, unlike the current method, does not require a clean room, wafers and other expensive resources and equipment. Instead, the technique relies on freeform manufacturing, which is similar in scope to 3-D printing but different in that material is removed instead of added.

The two-step process starts with inexpensive, pre-fabricated, industrial-quality metal deposited on polymer sheets. First, an electronic mechanical cutter is used to form patterns on the metal-polymer sheets. Second, after removing excessive areas, the electronics are printed onto any polymer adhesives, including temporary tattoo films. The cutter is programmable so the size of the patch and pattern can be easily customized.

Deji Akinwande, an associate professor and materials expert in the Cockrell School, believes Lu’s method can be transferred to roll-to-roll manufacturing.

“These initial prototype patches can be adapted to roll-to-roll manufacturing that can reduce the cost significantly for mass production,” Akinwande said. “In this light, Lu’s invention represents a major advancement for the mobile health industry.”

After producing the cut-and-pasted patches, the researchers tested them as part of their study. In each test, the researchers’ newly fabricated patches picked up body signals that were stronger than those taken by existing medical devices, including an ECG/EKG, a tool used to assess the electrical and muscular function of the heart. The team also found that their patch conforms almost perfectly to the skin, minimizing motion-induced false signals or errors.

The UT Austin wearable patches are so sensitive that Lu and her team can envision humans wearing the patches to more easily maneuver a prosthetic hand or limb using muscle signals. For now, Lu said, “We are trying to add more types of sensors including blood pressure and oxygen saturation monitors to the low-cost patch.”

Here’s a link to and a citation for the paper,

“Cut-and-Paste” Manufacture of Multiparametric Epidermal Sensor Systems by Shixuan Yang, Ying-Chen Chen, Luke Nicolini, Praveenkumar Pasupathy, Jacob Sacks, Su Becky, Russell Yang, Sanchez Daniel, Yao-Feng Chang, Pulin Wang, David Schnyer, Dean Neikirk, and Nanshu Lu. Advanced Materials DOI: 10.1002/adma.201502386 First published: 23 September 2015

This paper is behind a paywall.

Surgery with fingertip control

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In the future, ‘surgery at your fingertips’ could be literally true. Researchers at the University of Illinois at Urbana-Champaign have created a silicon nanomembrane that can be fitted onto the fingertips and could, one day, be used in surgical procedures. From the Aug. 9, 2012 news item on ScienceDaily,

The intricate properties of the fingertips have been mimicked and recreated using semiconductor devices in what researchers hope will lead to the development of advanced surgical gloves.

The devices, shown to be capable of responding with high precision to the stresses and strains associated with touch and finger movement, are a step towards the creation of surgical gloves for use in medical procedures such as local ablations [excising or removing tissue] and ultrasound scans.

Researchers from the University of Illinois at Urbana-Champaign, Northwestern University and Dalian University of Technology have published their study August 10, in IOP [Institute of Physics] Publishing’s journal Nanotechnology.

The Aug. 10,2012 posting on the IOP website  offers this detail about the research,

The electronic circuit on the ‘skin’ is made of patterns of gold conductive lines and ultrathin sheets of silicon, integrated onto a flexible polymer called polyimide. The sheet is then etched into an open mesh geometry and transferred to a thin sheet of silicone rubber moulded into the precise shape of a finger.

This electronic ‘skin’, or finger cuff, was designed to measure the stresses and strains at the fingertip by measuring the change in capacitance – the ability to store electrical charge – of pairs of microelectrodes in the circuit.  Applied forces decreased the spacing in the skin which, in turn, increased the capacitance.

The fingertip device could also be fitted with sensors for measuring motion and temperature, with small-scale heaters as actuators for ablation and other related operations

The researchers experimented with having the electronics on the inside of the device, in contact with wearer’s skin, and also on the outside. They believe that because the device exploits materials and fabrication techniques adopted from the established semiconductor industry, the processes can be scaled for realistic use at reasonable cost.

“Perhaps the most important result is that we are able to incorporate multifunctional, silicon semiconductor device technologies into the form of soft, three-dimensional, form-fitting skins, suitable for integration not only with the fingertips but also other parts of the body,” continued Professor Rogers [John Rogers, co-author of the study].

Here’s what an image of these e-fingertips,

Virtual touch. Electronic fingertips could one day allow us to feel virtual sensations. Credit: John Rogers/University of Illinois at Urbana-Champaign

Krystnell A offers a more detailed description of the e-fingetips in an Aug. 9, 2012 story for Science NOW,

Hoping to create circuits with the flexibility of skin, materials scientist John Rogers of the University of Illinois, Urbana-Champaign, and colleagues cut up nanometer-sized strips of silicon; implanted thin, wavy strips of gold to conduct electricity; and mounted the entire circuit in a stretchable, spider web-type mesh of polymer as a support. They then embedded the circuit-polyimide structure onto a hollow tube of silicone that had been fashioned in the shape of a finger. Just like turning a sock inside out, the researchers flipped the structure so that the circuit, which was once on the outside of the tube, was on the inside where it could touch a finger placed against it.

To test the electronic fingers, the researchers put them on and pressed flat objects, such as the top of their desks. The pressure created electric currents that were transferred to the skin, which the researchers felt as mild tingling. That’s a first step in creating electrical signals that could be sent to the fingers, which could virtually recreate sensations such as heat, pressure, and texture, the team reports online today in Nanotechnology.

…

Rogers says another application of the technology is to custom fit the “electronic skin” around entire organs, allowing doctors to remotely monitor changes in temperature and blood flow. Electronic skin could also restore sensation to people who have lost their natural skin, he says, such as burn victims or amputees.

Here’s a link to the article which is freely accessible for 30 days after publication, from the Aug. 9, 2012 news item on ScienceDaily,

Ming Ying, Andrew P Bonifas, Nanshu Lu, Yewang Su, Rui Li, Huanyu Cheng, Abid Ameen, Yonggang Huang, John A Rogers. Silicon nanomembranes for fingertip electronics. Nanotechnology, 2012; 23 (34): 344004 DOI: 10.1088/0957-4484/23/34/344004

My best guess is that free access will no longer be available by Sept. 7 (or so) , 2012. I last wrote about John Rogers’ work in an Aug. 12, 2011 posting about electronic tattoos.