Wearable Technology

Epidermal Electronics

Prof. Massimo De Vittorio

Epidermal electronics technology is based on matching the mechanical characteristics (elastic modulus and bending stiffness) of epidermis with flexible electronics, in order to insert traditional electronics in elastomeric sheets to be placed on skin via van der Waals forces and negligible mechanical loading, like a temporary tattoo. This strategy allows to overtake the incompatibility between the soft and curvilinear human body and rigid, planar, and physically static electronic devices.

Our aim is to eliminates this profound mismatch in properties developing a complete set of materials, production processes, and design layouts. Configuring hard inorganic functional materials into open mesh microarchitectures and embedding them in soft elastomeric film, allows the production of devices that can intimately integrate onto or into the human body for diagnostic, therapeutic, or surgical function.

The exploitation of both conductive and piezoelectric materials (i.e. AlN) and their specific characteristics such as ultrathin layout, optimized geometrical design will allow to reach the best stretching conditions, skin like mechanical properties and actuation capabilities for ultrasonic applications and self-powering.

This kind of technology could be used to create different kinds of devices, like sensors actuators or even multifunctional devices with wireless or radiofrequency control. The main goal is to develop a wearable platform for the monitoring of physiological parameters, like blood pressure and temperature, with the capability to communicate with external platform for the data transfer (phone, computer…).

Edible sensors

Prof. Massimo De Vittorio

The development of edible device for remote sensing of pH, ionic strength and temperature across all gastro intestinal (GI) tract is of great interest in health diagnostics. The control of pH is a important parameter to know if GI tract is in good condition or if are present an inflammatory states or an alteration of intestinal micro flora; moreover it is an important parameter useful to many pharmaceutical companies that have interest in understanding of pharmacokinetic (ADMA absorption, distribution, metabolism, and excretion) of their drug.

Biocompatible hydrogels such as cellulose derivatives, chitosan and acrylics undergo volume changes in response to environmental stimuli and are of great interest in medicine and biotechnology. These cross-linked hydrogels exhibit a swelling behaviour in aqueous solutions strongly dependent on several chemical and structural factors (i.e. hydrophilicity of polymer backbone, degree of cross-linking, density and type of fixed charges, amount of ionic groups and eventual presence of porosity) and by the properties of the aqueous solution in contact with the network (i.e. pH, ionic strength, temperature, electric field, presence specific molecules or other solvents).

Our aim is to develop an edible device (smart pill), whose volume changes can be detected through the application of a smart flexible packaging based on surface acoustic waves (SAW), micro piezoelectric transducers or magneto-elastics material – based wireless communication.

Furthermore, development of hydrogels cross-linked with antigen and antibody, that exhibiting different swelling behavior in dependence of presence of specific antigen could be envisioned. Antibody and antigen interactions are highly specific, and hydrogels that undergo volume changes or transitions by such an interaction may have potential for immunoassays and biosensor technology. It might be useful to diagnose a specific inflammation state or infection across GI tract.

Wearable Ultrasonic

Prof. Massimo De Vittorio

In order to monitor constantly physiologic health status (for example, hydration state) and for the diagnosis of disease, today much attention is given to the development of non-invasive wearable sensor which, acting as a miniature computer that can be worn on or attached to the body (as smart watches, smart glasses, clothing, jewelry or contact lens), can detect target analytes in extracorporeal fluid, i.e. tears, saliva, sweat and skin interstitial fluid. For instance, ultrasounds (US) are used as a non-destructive probe test in order to obtain structural information of solved analytes in different samples. In particular, in biology US are used to nondestructively study the structure, the equilibrium conformational fluctuations, and the thermodynamics of biomolecules and biomolecular processes.

At present wearable biosensor are based on electrochemical and colorimetric sensing. Our AIM is to develop a wearable device for chemical characterization of biological fluid using US. As a representative biofluids, sweat and saliva are of particular interest owing to their relative ease of non-invasive collection and their rich content of important biomarkers including electrolytes, proteins and small molecules (i.e. cortisol, sugars, drugs, tumor markers, etc.) able to give information about stress, hydration state, diabetes, etc.

The proposed device, represented schematically in Fig.1, is composed by: a flexible and wearable Ultrasound Transducer (which works both as a source as a detector, i.e. pulse echo mode), a propagation medium (a hydrogel) in which ultrasonic waves can propagate and in which a sensitive element is entrapped (protein). After the recognition of the target analyte, the sensitive element changes its acoustic properties, changing ultrasound velocity, amplitude and/or distorting US (exploiting non linear effects).

Smart patches for transdermal drug delivery

Prof. Massimo De Vittorio

Transdermal drug delivery is a potential method of drug administration that offers several advantages over traditional method such as injections and oral administration. Several drug delivery systems can be activated by external stimuli. Ultrasound has been used to trigger drug release from polymeric systems by causing their degradation.

Our aim is to create a wearable on-demand release system composed of an ultrasound-responsive hydrogel encapsulating specific drugs or proteins. Ultrasound can transiently disrupt the hydrogel structure causing the drug delivery. Ultrasound-activated method can realize precise and repeatable control release.

This system is a potentially valuable tool to engineer a dermal patch for topical administration of drugs. It can be used to create a platform composed of ultrasound-sensitive hydrogel, implanted with specific drugs, and a piezoelectric component for generating ultrasonic waves. This device allows to deliver and control therapeutic doses of drugs without the requirement for an external and impractical ultrasound source.