A fluid-supported 3D hydrogel bioprinting method.

Hydrogels are used in many biomedical applications, including regenerative medicine and surgical training phantoms. However, the ability to shape these materials into complex anatomical structures using additive manufacturing is limited in part by their low mechanical stiffness. We developed a hydrogel 3D printer, that projects patterns directly onto a thin layer of fluid-supported hydrogel precursor, which serves as a floating, liquid projection screen.

An Additive Manufacturing Technique for the Facile and Rapid Fabrication of Hydrogel-based Micromachines with Magnetically Responsive Components.

Polyethylene glycol (PEG)-based hydrogels are biocompatible hydrogels that have been approved for use in humans by the FDA. Typical PEG-based hydrogels have simple monolithic architectures and often function as scaffolding materials for tissue engineering applications. More sophisticated structures typically take a long time to fabricate and do not contain moving components.

Additive manufacturing of hydrogel-based materials for next-generation implantable medical devices.

Implantable microdevices often have static components rather than moving parts, and exhibit limited biocompatibility. This paper demonstrates a fast manufacturing method which can produce features in biocompatible materials down to tens of microns in scale, with intricate and composite patterns in each layer. By exploiting unique mechanical properties of hydrogels, we developed a "locking mechanism" for precise actuation and movement of freely moving parts, which can provide functions such as valves, manifolds, rotors, pumps, and delivery of payloads.

An implantable compound-releasing capsule triggered on demand by ultrasound.

Implantable devices have a large potential to improve human health, but they are often made of biofouling materials that necessitate special coatings, rely on electrical connections for external communication, and require a continuous power source. This paper demonstrates an alternative platform, which we call iTAG (implantable thermally actuated gel), where an implanted capsule can be wirelessly controlled by ultrasound to trigger the release of compounds. We constructed a millimeter-sized capsule containing a co-polymer gel (NiPAAm-co-AAm) that contracts above body temperature (i.

Mobile device for disease diagnosis and data tracking in resource-limited settings.

Background: Collection of epidemiological data and care of patients are hampered by lack of access to laboratory diagnostic equipment and patients' health records in resource-limited settings. We engineered a low-cost mobile device that combines cell-phone and satellite communication technologies with fluid miniaturization techniques for performing all essential ELISA functions.

Methods: We assessed the device's ability to perform HIV serodiagnostic testing in Rwanda and synchronize results in real time with electronic health records.

Microfluidic CD4+ T-cell counting device using chemiluminescence-based detection.

This letter demonstrates a microfluidic platform for enumerating CD4+ T-lymphocytes from whole blood using chemiluminescence as a detection method. We microfabricated traps in a chamber and coated them with anti-CD4 antibody to isolate CD4+ T-cells. Based on cell surface-bound CD3 antibodies conjugated with horseradish peroxidase, incubation with chemiluminescent substrate produced a current in the photodetector that was proportional to the number of captured CD4+ T-cells.

Polyelectrolyte complex membranes for specific cell adhesion.

The presentation of bioactive ligands on biomaterial surfaces is often confounded by the adsorption of proteins present in the biological milieu, rendering any type of cellular response nonspecific. We have engineered a polyelectrolyte complex membrane that demonstrates specific adhesion of various cell types for both two-dimensional (2D) and three-dimensional (3D) cell culture systems. Specific cell adhesion is achieved by a three-tiered structure: a silica cross-linked polycation as the bottom (first) tier, a nonfouling polyanion-poly(ethylene glycol) (PEG) conjugate as the intermediate (second) tier, and the cell-adhesion ligand as the top (third) tier.