Miaomiao Yang

A Physically Transient Form of Silicon Electronics

Reversible Implants Silicon electronics are generally designed to be stable and robust—it would be counterproductive if the key parts of your computer or cell phone slowly dissolved away while you were using it. In order to develop transient electronics for use as medical implants, Hwang et al. (p. 1640, see the cover) produced a complete set of tools and materials that would be needed to make standard devices. Devices were designed to have a specific lifetime, after which the component materials, such as porous silicon and silk, would be resorbed by the body. A platform of materials and fabrication methods furnishes resorbable electronic devices for in vivo use. A remarkable feature of modern silicon electronics is its ability to remain physically invariant, almost indefinitely for practical purposes. Although this characteristic is a hallmark of applications of integrated circuits that exist today, there might be opportunities for systems that offer the opposite behavior, such as implantable devices that function for medically useful time frames but then completely disappear via resorption by the body. We report a set of materials, manufacturing schemes, device components, and theoretical design tools for a silicon-based complementary metal oxide semiconductor (CMOS) technology that has this type of transient behavior, together with integrated sensors, actuators, power supply systems, and wireless control strategies. An implantable transient device that acts as a programmable nonantibiotic bacteriocide provides a system-level example.

Silk‐Based Conformal, Adhesive, Edible Food Sensors

An array of passive metamaterial antennas fabricated on all protein-based silk substrates were conformally transferred and adhered to the surface of an apple. This process allows the opportunity for intimate contact of micro- and nanostructures that can probe, and accordingly monitor changes in, their surrounding environment. This provides in situ monitoring of food quality. It is to be noted that this type of sensor consists of all edible and biodegradable components, holding utility and potential relevance for healthcare and food/consumer products and markets.

Silk-based resorbable electronic devices for remotely controlled therapy and in vivo infection abatement

Significance We present the demonstration of in vivo operation of a subcutaneously implanted, resorbable electronic device. The remotely controlled device was wirelessly activated after implantation, successfully eliminating infection, and subsequently dissolving in the surrounding tissue. This approach is a first step for the development of a class of implantable, technological, biomedical devices that resorb harmlessly, eliminating the need for retrieval after use. A paradigm shift for implantable medical devices lies at the confluence between regenerative medicine, where materials remodel and integrate in the biological milieu, and technology, through the use of recently developed material platforms based on biomaterials and bioresorbable technologies such as optics and electronics. The union of materials and technology in this context enables a class of biomedical devices that can be optically or electronically functional and yet harmlessly degrade once their use is complete. We present here a fully degradable, remotely controlled, implantable therapeutic device operating in vivo to counter a Staphylococcus aureus infection that disappears once its function is complete. This class of device provides fully resorbable packaging and electronics that can be turned on remotely, after implantation, to provide the necessary thermal therapy or trigger drug delivery. Such externally controllable, resorbable devices not only obviate the need for secondary surgeries and retrieval, but also have extended utility as therapeutic devices that can be left behind at a surgical or suturing site, following intervention, and can be externally controlled to allow for infection management by either thermal treatment or by remote triggering of drug release when there is retardation of antibiotic diffusion, deep infections are present, or when systemic antibiotic treatment alone is insufficient due to the emergence of antibiotic-resistant strains. After completion of function, the device is safely resorbed into the body, within a programmable period.

Materials and designs for wirelessly powered implantable light-emitting systems

Strategies are presented to achieve bendable and stretchable systems of microscale inorganic light-emitting diodes with wireless powering schemes, suitable for use in implantable devices. The results include materials strategies, together with studies of the mechanical, electronic, thermal and radio frequency behaviors both in vitro and in in-vivo animal experiments.

Inkjet Printing of Regenerated Silk Fibroin: From Printable Forms to Printable Functions.

A formulation of regenerated silk fibroin solution that can be easily functionalized and inkjet printed on numerous surfaces is developed. As an example, the inks can be printed on laboratory gloves that change color when exposed to bacteria.

Fabrication of Tunable, High‐Refractive‐Index Titanate–Silk Nanocomposites on the Micro‐ and Nanoscale

The combination of water-based titanate nanosheets dispersion and silk fibroin solution allows the realization of a versatile nanocomposite. Different fabrication techniques can be easily applied on these nanocomposites to manipulate the end form of these materials on the micro- and nanoscale. Easy tunability of the refractive index from n = 1.55 up to n = 1.97 is achieved, making it attractive for flexible, biopolymer-based optical devices.

Inkjet printing of functionalized silk proteins for enhanced stability and colorimetric bacterial sensing applications

We present the use of functionalized silk proteins for enhanced stability of biochemically active agents (e.g. horseradish peroxidase) in printed silk materials without the need of refrigeration storage. Direct printing of polydiacetylene vesicles conjugated with goat IgG antibody in printed silk materials for colorimetric detection of E. coli. has also been demonstrated.

Fully implantable and resorbable wireless medical devices for postsurgical infection abatement

We present a therapeutic application of a microfabricated implantable and resorbable medical device made out of fully degradable materials by demonstrating in vivo elimination of bacterial infection by wireless activation of the device after implantation. The device disappears upon its completion, requiring no retrieval.