Thermoresponsive Transient Radio Frequency Antennas: Toward Triggered Wireless Transient Circuits

Abstract

While implantable medical devices offer tremendous potential for treating a myriad of diseases and disorders, there are many situations in which such devices are only needed for short time periods, with extended presence or surgical removal leading to a host of undesired complications. To address this concern, researchers are working to develop implantable circuitry that eventually disintegrates. Prior work in this area leveraged known bioresorbable materials, but the lifetime of circuits formed from such materials is determined upon fabrication, and on‐demand, triggered disintegration is not possible. To better match the lifetime of an implanted device to the status of the condition it is monitoring or treating, it would be advantageous to be able to noninvasively trigger disintegration at a particular time, avoiding situations in which the device lifetime is either too short or too long. Thus, to enable implantable circuitry with wireless capabilities that can disintegrate upon external stimuli, thermoresponsive transient RF antennas are formed that exhibit stable wireless response in warm aqueous environments but disintegrate and irreversibly lose functionality when cooled below a critical temperature. Antennas are formed by embedding patterned networks of silver nanowires in a thermoresponsive polymeric binder, which maintains network conductivity in warm solution but disintegrates and releases the nanowires when solution temperature drops. Mild sintering enhances electrical properties of the conductive nanowire network and antenna response while maintaining the capability for disintegration. To reduce the undesired effects of swelling, devices are sandwiched between two parylene films. These thermoresponsive transient devices represent an important step toward the realization of wireless medical implants whose disintegration can be triggered at any time by an external cooling stimulus.

Synthesis and characterization of cellulose-based graft copolymers crosslinked by gamma-irradiation for enhanced oil recovery applications

“…The results showed that the cellulose concentration increase contributed to the decrease in the LCST of the copolymer. The LCST decrease was likely due to the increase in the ratio of hydrophobic cellulose monomers to hydrophilic methylcellulose monomers [23,24]. With a higher fraction of the hydrophobic cellulose moieties conjugated, the cellulose-methylcellulose copolymer is more prone to aggregation into core-shell micelles.…”

Leveraging the gel-to-sol transition of physically crosslinked thermoresponsive polymer hydrogels to enable reactions induced by lowering temperature

“…Stimuli-responsive materials have many potential applications due to their ability to respond dramatically to small environmental changes. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Temperature-responsive materials are particularly attractive as temperature is easy to control and is orthogonal to other relevant environmental conditions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] One possible application of such materials is to enable thermal initiation of mixing of separate payloads.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Temperature-responsive materials are particularly attractive as temperature is easy to control and is orthogonal to other relevant environmental conditions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] One possible application of such materials is to enable thermal initiation of mixing of separate payloads. This can be achieved through dramatic temperature-dependent transformation of a constraining material, allowing release from encapsulation, 2,[6][7][8]13,14 ow through a blockade or valve, [9][10][11][12] or the owing together of previously distinct solid-like gels.…”

Large‐Area Transient Conductive Films Obtained through Photonic Sintering of 2D Materials

“…Transient electronics that can dissolve or disappear under external or internal stimulus has aroused great interest in biology, [1][2] healthcare, [3][4] data storage, [5][6] and consumer electronics. [7][8][9] Transient electronic devices are typically constructed by nano/microscale thin films made of materials such as Mg, Zn, Si, SiO 2 , MgO, and ZnO that are degradable or dissolv-substrates to poly(vinyl alcohol) (PVA) substrates. The resulting transient films were 10 × 10 cm 2 in dimension with controllable thickness ranging from 60 to 440 nm and conductivities from 5.26 × 10 −2 to 1.92 × 10 4 S m −1 .…”

“…Transient electronics that can dissolve or disappear under external or internal stimulus has aroused great interest in biology, [ 1–2 ] healthcare, [ 3–4 ] data storage, [ 5–6 ] and consumer electronics. [ 7–9 ] Transient electronic devices are typically constructed by nano/microscale thin films made of materials such as Mg, Zn, Si, SiO 2 , MgO, and ZnO that are degradable or dissolvable when interacting with environmental molecules such as water, enzymes, and oxygen. [ 10–11 ] Despite that many innovative works in transient electronics have yielded diverse devices such as sensors, [ 12–14 ] power suppliers, [ 15–17 ] passive components, [ 18 ] and transistors, [ 19–21 ] the category of transient electronics remains inadequate as compared with other types of electronic devices, making construction of fully transient integration circuits extremely challenging due to limited selection in transient chips and devices.…”