A tetrode is a bundle of four microwires that can record from multiple neurons simultaneously in the brain of a freely moving animal. Tetrodes are usually electroplated to reduce impedances from 2-3 MΩ to 200-500 kΩ (measured at 1 kHz), which increases the signal-to-noise ratio and allows for the recording of small amplitude signals. Tetrodes with even lower impedances could improve neural recordings but cannot be made using standard electroplating methods without shorting. We were able to electroplate tetrodes to 30-70 kΩ by adding polyethylene glycol (PEG) or multiwalled carbon nanotube (MWCNT) solutions to a commercial gold-plating solution. The MWCNTs and PEG acted as inhibitors in the electroplating process and created large-surfacearea, low-impedance coatings on the tetrode tips.

Many medical devices that are implanted in the body use wires or wireless radiofrequency telemetry to communicate with circuitry outside the body. However, the wires are a common source of surgical complications, including breakage, infection and electrical noise. In addition, radiofrequency telemetry requires large amounts of power and results in low-efficiency transmission through biological tissue. As an alternative, the conductive properties of the body can be used to enable wireless communication with implanted devices. In this article, several methods of intrabody communication are described and compared. In addition to reducing the complications that occur with current implantable medical devices, intrabody communication can enable novel types of miniature devices for research and clinical applications.

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Introduction: Medication-taking is a routine instrumental activity of daily living affected by mild cognitive impairment (MCI) but difficult to measure with clinical tools. This prospective longitudinal study examined in-home medication-taking and transition from normative aging to MCI. Methods: Daily, weekly, and monthly medication-taking metrics derived from an instrumented pillbox were examined in 64 healthy cognitively intact older adults (Mage=85.5 y) followed for a mean of 2.3 years; 9 transitioned to MCI during study follow-up. Results: In the time up to and after MCI diagnosis, incident MCI participants opened their pillbox later in the day (by 19 min/mo; β=0.46, P<0.001) and had increased day-to-day variability in the first pillbox opening over time (by 4 min/mo) as compared with stable cognitively intact participants (β=4.0, P=0.003). Discussion: Individuals who transitioned to MCI opened their pillboxes later in the day and were more variable in their medication-taking habits. These differences increased in the time up to and after diagnosis of MCI. Unobtrusive medication-taking monitoring is an ecologically valid approach for identifying early activity of daily living changes that signal transition to MCI.

Objective: This paper reports the iterative redesign, feasibility and usability of the Comprehensive Mobile Assessment of Pressure (CMAP) system's mobile app used by Veterans with SCI. Design: This three-year, multi-staged study used a mixed-methods approach.