Sensing pressure at the speed of light

In our latest paper, an optical pulse travels through a branched waveguide network. A ranging sensor made for consumer electronics is put to work measuring the arrival time distribution of the pulse after it splits and travels through branches with three different lengths. Rubber “switches” squeeze down on each branch when pressure is applied. This setup means a single optical sensor can monitor multiple pressure points in a system. Here, Dr. George Lin uses the setup to keep track of an object rolling around on a plate. Since the materials in the sensors are soft polymers, including the waveguide material, it’s a good match for soft robotics. It also works underwater.

Our low-level time-of-flight sensor reading code and sample data are available online.

Soft optics

The fall Materials Research Society meeting was a hybrid of in-person and remote presentations. Here is our work on characterizing a soft, micromolded silicone layer for its pressure-dependent optical properties. Independent Study students Michael Portaro and Rio Brittany, both in ECE, developed different parts of the project during 2021. The end result was a material that lets increasing amounts of light through when pressure is increased from 0 to 2 PSI. Applications of this microstructured material include touch sensors for soft robotic hands and human-computer interfaces.

Student has a solid grasp of the material

Research Experience for Undergraduates (REU) Student Muhemmad Yassin got a microelectromechanical (MEMS) gripper to grasp this conductive fiber as part of his summer research in the IMPACT REU program. This project aims to create a porous, breathable packaging system for MEMS in wearable and flow-through applications. Muhemmad is now taking the project on the road at the IMPACT convocation where dozens of students from different cleanroom REU sites meet. If you’re interested in participating next year, get in touch using the “Join the Lab” link.

A gripping presentation

Here is Sushmita’s talk from the 2021 Manufacturing Science and Engineering Conference on designing microelectromechanical system (MEMS) layouts that align with one-of-a-kind structures like a piece of fabric. Most fabrics do have a uniform and predictable structure that can be described by a measurement such as “threads per inch.” However, threads do not have the submicron dimensional accuracy of a MEMS layout on a silicon wafer. Threads are soft, often made from natural fibers that vary from batch to batch, and conditions such as tension during assembly control the tightness of the weave or knit. Therefore, on the microscale, each piece of fabric is different. In this presentation, images of individual fabric pieces are processed to generate a MEMS gripper layout that will attach microdevices to specific fibers in the swatch. The focus of this research is on automated image processing methods that quickly identify good gripper locations. The desired result is a technology that lets engineers use flexible, porous, multimaterial fabrics as new packaging materials for MEMS devices.