SynCells: A 60 × 60 μm² Electronic Platform with Remote Actuation for Sensing Applications in Constrained Environments

Abstract

Autonomous electronic microsystems smaller than the diameter of a human hair (<100 μm) are promising for sensing in confined spaces such as microfluidic channels or the human body. However, they are difficult to implement due to fabrication challenges and limited power budget. Here we present a 60 × 60 μm electronic microsystem platform, or SynCell, that overcomes these issues by leveraging the integration capabilities of two-dimensional material circuits and the low power consumption of passive germanium timers, memory-like chemical sensors, and magnetic pads. In a proofof-concept experiment, we magnetically positioned SynCells in a microfluidic channel to detect putrescine. After we extracted them from the channel, we successfully read out the timer and sensor signal, the latter of which can be amplified by an onboard transistor circuit. The concepts developed here will be applicable to microsystems targeting a variety of applications from microfluidic sensing to biomedical research.

Memristor Circuits for Colloidal Robotics: Temporal Access to Memory, Sensing, and Actuation

“…The approximation is made on the basis that the devices are significantly smaller than the scales of interest in typical microrobotic applications, such as sensing in pipelines and reactors. This treatment is consistent with prior studies on micrometer-sized sensor nodes, both mobile [39,41] and immobile. [5,23] In the presence of a large chemical concentration gradient, however, the approximation may become less valid.…”

“…In the absence of chronometry, basic control‐theoretic notions of stability, robustness, and task‐performance become impossible to guarantee in any but the most trivial of control problems. [ 62,63 ] While there have been relevant efforts based on time‐dependent diffusion, [ 64 ] materials erosion, [ 41 ] and biological cell activity, [ 65 ] their temporal information is only communicated to the operator in the end and isolated from other robotic elements, if any. By contrast, temporal access to the memory, sensors, and actuators on‐board is desired for microrobots that sense, think, and act autonomously.…”

“…[22] To this end, a few research groups have fabricated sophisticated immobile sensor nodes [23][24][25][26] that exceed 250 μm in size and are externally supervised or monitored, with key tasks outsourced off-board such as recording of the sensed information. The infrequent breakthroughs in this area are contrasted with a rich body of literature on actuation, [4,[27][28][29][30] locomotion, [31][32][33][34][35] energy harvesting/ storage, [36,37] and sensing modules [38][39][40][41] for autonomous colloidal robotics. These components, which often tolerate a lower fabrication resolution but require IC-incompatible novel materials, present an opportunity for emerging fabrication platforms like inkjet printing, [38,[42][43][44] screen printing, [45,46] stamping, [47] and colloidal self-assembly.…”

Colloidal State Machines as Smart Tracers for Chemical Reactor Analysis

“…[54][55][56][57] However, conventional tracers are not capable of unraveling further details about the interior of reactors since they only have at most two states, making them insufficient for more advanced applications. The considerable advances in microrobotics, [58][59][60][61][62][63][64][65][66][67][68][69][70][71] broadly defined, open up new possibilities to temporally and spatially map a far greater number of variables in such complex systems with far fewer applied probes.…”

High Energy Density Picoliter Zn-Air Batteries for Colloidal Robots and State Machines

“…To date, the majority of millimeter-scale sensors were either powered by solar cells [2][3][4]20 or did not have internal power sources. [21][22][23][24] However, to enable autonomous operation of colloidal robots in confined environments, such as pipelines, underground and in-vivo, on-board, high energy density units are required since access to ambient energy sources such as illumination are necessarily limited. Thus, there is a pressing need for integrating tiny batteries with the tiny sensors and robots.…”