Helping Blind People Grasp: Evaluating a Tactile Bracelet for Remotely Guiding Grasping Movements.

The problem of supporting visually impaired and blind people in meaningful interactions with objects is often neglected. To address this issue, we adapted a tactile belt for enhanced spatial navigation into a bracelet worn on the wrist that allows visually impaired people to grasp target objects. Participants' performance in locating and grasping target items when guided using the bracelet, which provides direction commands via vibrotactile signals, was compared to their performance when receiving auditory instructions. While participants were faster with the auditory commands, they also performed well with the bracelet, encouraging future development of this system and similar systems.

Synthesis and Characterization of Cationic Hydrogels from Thiolated Copolymers for Independent Manipulation of Mechanical and Chemical Properties of Cell Substrates.

Cells sense both mechanical and chemical properties in their environment and respond to these inputs with altered phenotypes. Precise and selective experimental manipulations of these environmental cues require biocompatible synthetic materials, for which multiple properties can be fine-tuned independently from each other. For example, cells typically show critical thresholds for cell adhesion as a function of substrate parameters such as stiffness and the degree of functionalization. However, the choice of tailor-made, defined materials to produce such cell adhesion substrates is still very limited. Here, a platform of synthetic hydrogels based on well-defined thiolated copolymers is presented. Therefore, four disulfide crosslinked hydrogels of different composition by free radical polymerization are prepared. After cleavage with dithiothreitol, four soluble copolymers P1-P4 with 0-96% cationic monomer content are obtained. P1 and P4 are then combined with PEGDA3500 as a crosslinker, to fabricate 12 hydrogels with variable elasticity, ranging from 8.1 to 26.3 kPa and cationic group concentrations of up to 350 µmol cm-3 . Systematic analysis using COS7 cells shows that all of these hydrogels are nontoxic. However, successful cell adhesion requires both a minimal elasticity and a minimal cationic group concentration.