Recent research on medical implants has asked for more reliable and biocompatible hermetic packaging techniques with integrated circuits (IC). Besides, high-density multi-channel IC interconnects also become a major requirement to realize high-resolution application on electrical stimulation and recording. Previously proposed packaging methods are mostly based on wire bonding technique to bond pads on chip to pads on biocompatible ceramics substrate individually. However, the real medical implant product that are currently in use or under development still lack the high-density packaging techniques which limit the further development of application [1-3].

The development of film package in implantable electronic medical device is one of the major solution. Rodger et al [4] introduced a biocompatible interconnect film packaging method based on parylene film, which is already a huge achievement of high-density packaging techniques. Also, Rodger have demonstrated the parylene flex and high-density multi-channel retinal IC chip have a strong bonding to survive during surgical manipulation. Unfortunately, water penetration problem of parylene C film still exists in the in vivo corrosive body fluid environment that could not meet the requirement of long-term implantation in humans. Thus, A desired medical implants of lifetime 10 years are mostly depends on the packaging design protection on the device.

Thin film encapsulation has been studied on flexible OLED packaging using incompatible three layers MgF₂/ZnS film, which has a good water vapor and oxygen barrier capability that could substantial improvement in lifetime [5]. In this work, we built an ideal packaging design by introducing multiple biocompatible organic/inorganic film together on PI substrate. The water penetration route of multiple film will significantly enhanced due to the multiple films design. The fabrication and functional validation of the well designed multiple film are based on PI substrate of 1 µm organic parylene C (PA) and 50 nm inorganic aluminum oxide (Al₂O₃) film, which are five layers PA/Al₂O₃/PA/Al₂O₃/PA design structure (Fig. 1). PA and Al₂O₃ film are deposited using advanced chemical vapor deposition (CVD) and atomic layer deposition (ALD) technology, respectively. Specifically, the films packaging sample and the He leakage test sample are shown on fig.2a and fig.2b, respectively. The He leakage test pressure is 1×10^-10 Pa·m³/s, meeting FDA 10 year in vivo implantation standard. Furthermore, the in vivo biological compatibility results of cell relative growth rate (RGR) also demonstrate highly biocompatible level (0 level) in cell L929 (Fig. 3). 

In conclusion, the state-of-the-art multiple organic/inorganic film packaging has been successfully demonstrated as a useful package design. Thus, synergistic organic/inorganic packaging by “multiple PA and Al₂O₃ film” provides a promising film package design that ensures highly biocompatible and long-term implantable for medical implants market. Next, we will use this film packaging design in our 1024 high-density retinal product to achieve long time reliable implantation in vivo.

Microfluidics is a multidisciplinary technology which enables the face-lift crossing a wide range of applications such as life science research, point-of-care diagnostics and personal medicine. Polymer materials, especially thermoplastics, are dominating this emerging market due to the low material cost and the ease of mass production. This talk reports the new development of major fabrication technologies for making polymer, especially thermoplastic microfluidic chips, including micro tooling, injection molding, bonding and surface treatment. The talk also discusses about the key challenges in fulfilling the needs of next generation microfluidic products.

Ordered fiber bundles (FBs) operating in the mid-infrared spectral region are desirable for the collection and delivery of thermal images in extreme (e.g. under nuclear irradiation) or unfavorable environments (e.g. stray electromagnetic fields, in restricted spaces, etc.). In this paper, high-resolution chalcogenide FBs suitable for transmitting images in the 1.5-6.5 μm and 3-11 μm spectral ranges were prepared and characterized. Recently, The FB was composed of ~200,000 single fibers with a GeAsTeSe glass core of 15 μm in diameter and a polyetherimide (PEI) cladding of 16.8 μm in diameter. The fiber shows good transparency in the 3-12 μm spectral region. The resulting FB presents active area of ~79 % and a crosstalk of ~1 %. Clear thermal images of a human body were obtained using the FB, encouraging that it could be a promising prospect in fiber-optic thermal imaging in medical and industrial applications, in particular for endoscopic thermal imaging.

The functionalities of traditional optical component are mainly based on the phase accumulation through the propagation length, leading to a bulky optical component like lens and waveplate. Plasmonic metasurfaces composed of two-dimensional (2D) artificial structures have attracted a huge number of interests due to their ability on controlling the optical properties including electromagnetic phase as well as amplitude at a subwavelength scale. They therefore pave a promising way for the development of flat optical devices and integrated optoelectronic systems. In this talk, several research topics for photonic applications based on metasurfaces will be performed and discussed: high efficiency anomalous beam deflection, highly dimensional holographic imaging, versatile polarization generation and analysis, multi-functional and tunable Metadevices, and engineering non-radiating anapole mode for the generation of toroidal dipole moment in free space.

Infrared (IR) spectroscopy probes the phonon vibrational states of molecules by measuring wavelength-dependent optical absorption in the mid-infrared regime (2.5-25 µm wavelength or 400-4,000 cm^-1 in wave number).  It is widely recognized as the gold standard for chemical analysis given its superior specificity. Traditional IR spectroscopy relies on fragile bench-top instruments located in dedicated laboratories, and is thus not suitable for emerging field-deployed applications such as in-line industrial process control, environmental monitoring, and point-of-care diagnosis. Recent strides in photonic integration technologies provide a promising route towards enabling miniaturized, rugged platforms for IR spectroscopic analysis. It is therefore attempting to simply replace the bulky discrete optical elements used in conventional IR spectroscopy with their on-chip counterparts. This size down-scaling approach, however, cripples the system performance as both the sensitivity of spectroscopic sensors and spectral resolution of spectrometers scale with optical path length.

To address this challenge, we present the development of two novel photonic device designs uniquely capable of reaping performance benefits from microphotonic scaling [1].  Firstly, we leverage strong optical and thermal confinement in judiciously designed microcavities to circumvent the thermal diffusion and optical diffraction limits in conventional photothermal sensors and achieve parts- per-billion (ppb) level gas molecule limit of detection. Photothermal spectroscopy has been predicted as a technique 10⁴ times more sensitive than conventional microcavity absorption spectroscopy [2, 3]. We propose a new technique that monitors the shift in cavity resonance as a result of heating.  Resonant absorption of cavity light by the gas molecules thermally heats the cavity, producing a large resonant shift in a suitably designed microdisk cavity, as schematically illustrated in Fig. 1. 

In the second example, a novel spectrometer technology based on on-chip digital Fourier Transform InfraRed (dFTIR) is proposed to overcome the aforementioned spectral resolution limit facing current on-chip spectrometers. As schematically depicted in Fig. 2, the dFTIR spectrometer consists of an interferometer with arms comprising a series of cascaded optical switches connected by waveguides of varying lengths. Each permutation of the switches modifies the physical waveguide path lengths and thus spectrometer configurations. Such a dFTIR approach is far more effective for varying the optical path length than index modulation and hence enables perform metrics comparable or even superior than conventional benchtop instruments.  The spectrometer design fulfills Fellgett’s advantage offering dramatically-improved SNR and enables sub-nm spectral resolution (as projected in Fig, 3) on a millimeter-sized, fully-packaged photonic integrated chip without mechanical moving parts.