Since the invention by Arthur Ashkin in 1986, the optical tweezers have been an important tool for physics and biology. These optical tweezers can trap micro/nanoparticles without any physical contact while simultaneously measuring pN-level forces and nm displacements. However, traditional optical tweezers based on objective lenses have been limited within research labs, due to the expensive and bulky setup and susceptibility to environmental fluctuations. In this talk, I will discuss the recent progress on fiber-based optical tweezers, with an aim of bringing this technology out of the labs. Our fiber optical tweezers are small (~ 1x1x0.5 in^3), modular, and portable, while maintaining the capabilities of both microparticle trapping and nm-resolution displacement measurements. I will focus on a unique application of the modular fiber tweezers in disease diagnosis by single cell stiffness interrogation. Other potential applications including brain tissue mechanical measurements and trapping in air will also be discussed.

Fabrics have been used for centuries to passively communicate information through pattern, color and form factor.  Advances in multi-material fiber drawing processes have enabled the integration of both light emitting and high bandwidth optical devices within fibers of ever shrinking dimensions, thereby facilitating the development of a new form of fabric communication applications.  Fibers with embedded light emitting diodes are capable of transmitting information to the surrounding, while photodiode fiber devices are capable of receiving and transducing information transmitted optically, changing the way we think about fabrics and textiles in general.  In this talk, I will describe the integration of LEDs and high bandwidth photodiode dice within thermoplastic fibers with cross-sectional dimensions below 300 microns.  Successful integration of semiconductor devices such as InGaN, Si, InGaAs, or GaAs photodiodes permit broad spectrum coverage from the visible to 1.5 microns.  The resulting fibers may be converted into fabrics via conventional textile processes such as weaving, knitting, braiding and more. A few use cases will be described such as communicating apparel for roadway safety, LiFi to garments and caps, as well as broadcast of data in real time for physiological monitoring.

Over the last 25 years, various spectroscopic, Doppler, interferometric, and lifetime based optical measurement technologies have been developed for investigating brain function in humans and in animal models. My research has focused on developing and applying methods to measure cerebral blood flow and oxygenation. I will start by describing the development of functional near infrared spectroscopy of hemoglobin oxygenation and diffuse correlation spectroscopy of blood flow for measuring human brain function. I will then review the development of laser speckle contrast and multi-spectral optical intrinsic signal imaging for exploring the relationship between blood flow and oxygenation with neuronal activity in animal models, enabling us to better interpret human brain function measurements, including those made with functional magnetic resonance imaging. I will then discuss the development of two photon microscopy and optical coherence tomography methods for advancing the spatial resolution with which blood flow and oxygenation can be measured. I will couple descriptions of each of these technological developments with examples of their impactful applications.