Microbots: Medical Infantry | David Cappelleri | TEDxPurdueU
## People - Joe + subject of stroke + suffered a massive stroke. ## Organizations - Purdue + location where the speaker showcased fabricated robots. ## Tools, Tech & Products - Electromagnets + used to surround the workspace of the robot and control it to move in the plane. - Magnetic feet + magnetic properties different from the ones on the robot's hat, added to the robot for rough terrain negotiation. - Magnetic body + core component of the robot. - Soft compliant structure + used as the end effector, deforms when pushed on an object. - Micro force sensor + used in conjunction with the soft compliance structure to measure forces. - Micro robot + small bot with onboard computers, cameras, intelligence, arms, and hands (future goal). ## Concepts & Definitions - Microbot/Micro robot + a robot that is very small, submillimetre dimensions. - Cytoskeleton + the skeleton inside a single cell. - Mechanobiology + the study of forces and how the cell reacts to them and develops. - Stiffness (cell) + the force displacement relationship for the cells. ## Numbers & Data - 100 microns + diameter of a human hair (for comparison). - 8 human hair + width approximation for the microbots discussed initially. - 7 human hair + height approximation for the microbots discussed initially. - Three human hairs wide by four human hairs long + dimensions of the developed tumbling robot. - 700 microns footprint + size of one of the sensing mobile micro robots. - Four millimeters by four millimeters + size of the prototyped coils. - Two millimeters in diameter + size of the independently moving robots prototyped. - 300 microns in diameter + desired size for the micro coils for scalable manufacturing. ## Claims & Theses - The first thing you need to know about a micro robot is it's very small so we say its submillimetre dimensions. - If the robot is really small, you can't stick a battery on this robot for power. - We can surround the workspace of the robot with electromagnets and control it to move in the plane. - We can give this robot some magnetic feet to negotiate rough terrain. - We can cycle the robot to roll and tumble to the target location. - We can get the robot to "walk along the surface" using a stick-slip motion. - The micro robot can help in applications where users don't know how much force they are actually pushing the cell with. - A normal cell will have a different stiffness property than say a cancer cell. - We can use a vision based micro force sensor to observe deformation and back out the force. - We can plan a path around obstacles in the workspace, allowing the robot to move autonomously. - We can control teams and swarms of these robots working independently. - By shrinking the electromagnets to the size of the robots and arranging them in an array, we can achieve independent motion. - We can use micro strips of wire arranged in two layers to achieve directional force control. - The more exciting and more impactful applications are the medical domain. - These micro robots offer unprecedented capabilities that you just can't get with these larger macro scale robots. ## Mechanisms & Processes - Magnetic attraction/repulsion + used by electromagnets to guide the robot. - Negotiation of rough terrain + achieved by using magnetic feet to allow the robot to roll and tumble. - Tumbling locomotion + method to get the robot over rough terrain on a sticky surface. - Sliding mode operation + mechanism involving a stick-slip motion to get the robot to walk along a surface. - Cell reconfiguration + the cytoskeleton reconfigures itself to be stiffer where force is applied. - Force measurement process + observing deformation with a camera attached to a microscope, and using stiffness data to calculate force. - Autonomous navigation + the robot planning a path and following GPS coordinates around obstacles. - Independent control of magnetic robots + achieved by using patterned coils/micro strips to generate specific directional forces. - Directed force application for cell characterization + applying small, controlled forces to measure cell stiffness. ## Examples & Cases - A human hair + used as a scale reference (100 microns diameter). - The robot dimensions are about 3 human hairs wide by 4 human hairs long. - Using the robot on biological tissue + where sticky surface prevents simple pulling. - The robot negotiating the surface of a penny + example of navigating different features. - The robot moving over different bumps in the workspace + example of traversing varied topography. - The robot moving up and down inclined planes + example of managing slopes. - Biologists using a petri dish to move and arrange individual cells. - Applying force to two different cells (Cell A and Cell B) + example used to compare their stiffness. - Using the sensing mobile micro robot on a microsphere + example showing deformation tracking. - Controlling a team of three robots using electromagnets + example demonstrating coordinated movement. - Using micro strips of wire to achieve force to the right, left, up, and down on two robots simultaneously + example of independent, patterned force application. - Joe's case + example of a massive stroke requiring clot removal from a deep brain area. ## Trade-offs & Alternatives - Large-scale robot vs. Micro robot: Cannot put a battery on a tiny robot. - Standard magnets (on a "hat") vs. Electromagnets: Electromagnets can be turned on and off. - Large, bulky tires vs. Magnetic feet: Magnetic feet allow negotiation on the body's internal sticky surfaces. - Using probes (current method) vs. Micro robot: Probes lack precision on applied force, potentially damaging cells. - Manual force application vs. Vision-based force sensor: The sensor allows observation and quantification of force/deformation. - Controlling a single robot vs. Controlling teams/swarms: Individual control vs. collective action. - Using micro coils (high cost/difficulty) vs. Micro strips of wire (cheaper/easier): Alternative technology for micro-scale force generation. ## Counterarguments & Caveats - If the electromagnet on the robot's hat is not used, the robot can be guided by magnetic fields. - If the robot is pushed with a probe, the user might not know how much force they are actually pushing the cell with. - The initial electromagnets create global fields, which prevents independent control of multiple robots. - Making micro coils or strips at the micro scale is very hard and very expensive. ## Methodology - Electromagnet array setup + used to surround the workspace and guide the robot. - Developing magnetic feet + required a different magnetic property than the main robot magnet. - Utilizing a soft compliant structure + used as an end effector to measure mechanical properties. - Microscopy and Camera integration + required to observe deformation for force calculation. - Programming micro coils/strips + used to generate patterned, controlled forces for independent movement. ## References Cited - None explicitly cited (the speaker speaks about the field of mechanobiology). ## Conclusions & Recommendations - The ultimate goal is to use the microbots at the micro scale. - If you can think of anything, the microbots can do it. - The only limit is your imagination. ## Implications & Consequences - Using microbots in the body could allow removal of blood clots where surgeons struggle. - Targeted drug delivery with microbots could allow higher concentrations of drugs at the tumor site compared to traditional diffusion. - Microbots could enable less invasive biopsies by taking tissue samples inside the body. - Microbots in the future could have onboard computers, cameras, intelligence, arms, and hands. ## Open Questions - How to build micro-scale electromagnets or arrays cheaply/easily enough for widespread use (addressed by micro strips). ## Verbatim Moments - "The only limit is your imagination." - "Microbots, microbots." - "This is an unscripted event in Joe's life in my life."