This paper presents an implantable parylene-based wireless pressure sensor for biomedical pressure sensing applications specifically designed for continuous intraocular pressure (IOP) monitoring in glaucoma patients. It has an electrical LC tank resonant circuit formed by an integrated capacitor and an inductor coil to facilitate passive wireless sensing using an external interrogating coil connected to a readout unit. Two surface-micromachined sensor designs incorporating variable capacitor and variable capacitor/inductor resonant circuits have been implemented to realize the pressure-sensitive components. The sensor is monolithically microfabricated by exploiting parylene as a biocompatible structural material in a suitable form factor for minimally invasive intraocular implantation. Pressure responses of the microsensor have been characterized to demonstrate its high pressure sensitivity ( > 7000 ppm/mmHg) in both sensor designs, which confirms the feasibility of pressure sensing with smaller than 1 mmHg of resolution for practical biomedical applications. A six-month animal study verifies the in vivo bioefficacy and biostability of the implant in the intraocular environment with no surgical or postoperative complications. Preliminary ex vivo experimental results verify the IOP sensing feasibility of such device. This sensor will ultimately be implanted at the pars plana or on the iris of the eye to fulfill continuous, convenient, direct, and faithful IOP monitoring.[2008-0111].

This paper presents an embedded chip integration technology that incorporates silicon housings and flexible Parylene-based microelectromechanical systems (MEMS) devices. Accelerated-lifetime soak testing is performed in saline at elevated temperatures to study the packaging performance of Parylene C thin films. Experimental results show that the silicon chip under test is well protected by Parylene, and the lifetime of Parylene-coated metal at body temperature (37°C) is more than 60 years, indicating that Parylene C is an excellent structural and packaging material for biomedical applications. To demonstrate the proposed packaging technology, a flexible MEMS radio-frequency (RF) coil has been integrated with an RF identification (RFID) circuit die. The coil has an inductance of 16 μH with two layers of metal completely encapsulated in Parylene C, which is microfabricated using a Parylene-metal-Parylene thin-film technology. The chip is a commercially available read-only RFID chip with a typical operating frequency of 125 kHz. The functionality of the embedded chip has been tested using an RFID reader module in both air and saline, demonstrating successful power and data transmission through the MEMS coil.

Ocular syphilis is reemerging as an important cause of uveitis in the new era of common co-infection with HIV. This study will reveal the clinical and laboratory characteristics in the group of individuals co-infected with ocular syphilis and HIV compared with HIV-negative individuals. In this retrospective observational case series, medical records of patients diagnosed with ocular syphilis with serologic support from 2008 to 2014 were reviewed. Ocular and systemic manifestation and laboratory profiles were reviewed. Twenty-nine eyes of 16 consecutive patients (10 HIV-positive and 6 HIV-negative) were included. All patients were males, and mean age of onset for ocular syphilis was 43 (mean 42.65 ± 13.13). In both HIV-positive and HIV-negative groups, ocular manifestations of syphilis were variable including anterior uveitis (4 eyes), posterior uveitis (8 eyes), panuveitis (13 eyes), and isolated papillitis (4 eyes). In HIV-positive patients, panuveitis was the most common feature (12/18 eyes, 67 %) and serum rapid plasma reagin (RPR) titers were significantly higher (range 1:64–1:16,348; mean 1:768; p = 0.018) than in HIV-negative patients. Upon the diagnosis of ocular syphilis in HIV-positive patients, HIV-1 viral load was high (median 206,887 copies/ml) and CD4 cell count ranged from 127 to 535 cells/ml (mean 237 ± 142; median 137). Regardless of HIV status, cerebrospinal fluid (CSF) exam was frequently abnormal: positive CSF fluorescent treponemal antibody absorption (FTA-ABS) or Venereal Disease Research Laboratory (VDRL) test results in seven patients or either elevated CSF WBC count or elevated CSF protein in six patients. Our results reveal that the patients with ocular syphilis with high serum RPR titers may have concomitant HIV infection requiring further testing for HIV status and ocular syphilis is likely associated with the central nervous system involvement and therefore needs to be managed according to the treatment recommendations for neurosyphilis.