Fig 1.
A—DST nano-T temperature logging device, as supplied; B—illustration of vaginal ring device with cavity for insertion of temperature logger.
C—construction of temperature logging device encapsulated in silicone elastomer tubing for vaginal testing in macaques; C1 shows the silicone elastomer tubing (8.0 mm overall diameter); C2 shows the logger inserted into the silicone elastomer tubing; C3 shows the tubing end-sealed with silicone elastomer.
Fig 2.
In vitro testing of DST nano-T temperature logging devices using sampling rates of 8 and 60 min.
Devices were placed in a shaking orbital incubator set to 37°C, removed from the incubator at 120 min, returned to the incubator at 240 min, and then finally removed at 360 min. A—devices as supplied, i.e. non-encapsulated. B—devices sealed in silicone elastomer tubing. C—devices sealed in silicone elastomer tubing and placed in 10 mL of simulated vaginal fluid contained in a glass beaker.
Fig 3.
Effect of silicone elastomer sheath thickness on the in vitro temperature responsiveness of encapsulated DST nano-T devices in SVF.
A—Four removals and re-insertions were performed. The removal periods were 20, 30, 30 and 40 min. Temperature was recorded at 20 sec intervals; data points are not shown for sake of clarity. B—Magnified view of the first removal and re-insertion period, showing the cooling and heating trends as a function of sheath thickness.
Fig 4.
In vitro testing of silicone elastomer encapsulated DST nano-T devices immersed in incubated SVF, showing the temperature responses subject to four different use schedules.
In each case, the sampling interval was 8 min. A—device maintained at 37°C; B—device removed from incubator at 96 h; C—device removed and returned to incubator numerous times during a 12 h period; D—device removed from incubator for progressively longer time periods before being returned.
Table 1.
Statistical data for DST nano-T devices placed in various in vitro and in vivo environments.
Fig 5.
Temperature response of the silicone elastomer-encapsulated temperature logging devices before, during and immediately after vaginal insertion in cynomolgus macaques (n = 3).
The arrows indicate vaginal insertion of the device. The dashed line (RT) indicates ambient laboratory temperature.
Fig 6.
Temperature response versus time for vaginally and subcutaneously administered temperature loggers in cynomolgus macaques.
Each graph shows a representative plot for a single macaque. Solid and dashed arrows indicate removal and re-insertion of the vaginal device, respectively. Laboratory temperature as measured by a control temperature logging device is indicated by the dashed line at ~22°C. A—vaginal device worn continuously over a 7-day period. B—vaginal device removed after 3 days placement. C—vaginal device removed and reinserted on three different occasions during the 7-day period.
Fig 7.
Evaporative cooling effect following removal of the silicone elastomer encapsulated DST nano-T device from the macaque vagina.
Temperatures recorded by the vaginal device drop immediately after removal and increase with time. The lower temperatures measured soon after removal are due to evaporation of PBS wash buffer from the encapsulated device. As the water evaporates, the measured temperature rises. To more fully appreciate the evaporative cooling phenomenon, the baseline laboratory data, which is relatively low due to remote location of the sensor, can be shifted to 22.3°C.
Fig 8.
Effect of DST nano-T temperature sampling interval on measured battery life.
Dotted line indicates battery life at 8 min sampling interval.