Characteristics of an Implantable Blood Pressure Sensor Packaged by Ultrafast Laser Microwelding

Abstract

We propose a new packaging process for an implantable blood pressure sensor using ultrafast laser micro-welding. The sensor is a membrane type, passive device that uses the change in the capacitance caused by the membrane deformation due to applied pressure. Components of the sensor such as inductors and capacitors were fabricated on two glass (quartz) wafers and the two wafers were bonded into a single package. Conventional bonding methods such as adhesive bonding, thermal bonding, and anodic bonding require considerable effort and cost. Therefore CO2 laser cutting was used due to its fast and easy operation providing melting and bonding of the interface at the same time. However, a severe heat process leading to a large temperature gradient by rapid heating and quenching at the interface causes microcracks in brittle glass and results in low durability and production yield. In this paper, we introduce an ultrafast laser process for glass bonding because it can optimize the heat accumulation inside the glass by a short pulse width within a few picoseconds and a high pulse repetition rate. As a result, the ultrafast laser welding provides microscale bonding for glass pressure sensor packaging. The packaging process was performed with a minimized welding seam width of 100 μm with a minute. The minimized welding seam allows a drastic reduction of the sensor size, which is a significant benefit for implantable sensors. The fabricated pressure sensor was operated with resonance frequencies corresponding to applied pressures and there was no air leakage through the welded interface. In addition, in vitro cytotoxicity tests with the sensor showed that there was no elution of inner components and the ultrafast laser packaged sensor is non-toxic. The ultrafast laser welding provides a fast and robust glass chip packaging, which has advantages in hermeticity, bio-compatibility, and cost-effectiveness in the manufacturing of compact implantable sensors.

Enhanced Hemocompatibility of a Direct Chemical Vapor Deposition-Derived Graphene Film

“…Due to the use of a graphene film, which is free of polymer contamination or functionalization, our study might reflect the intrinsic antithrombogenic properties of the graphene film. Glass-based sensors are widely used in various blood-contacting applications, including measurements of blood pressure, blood oxygen concentration, and blood glucose levels, as well as ABO blood group typing and erythrocyte counting. We believe that using a graphene film as a modification coating could enhance the application of these blood-contacting glass-based sensors.…”

Commercial Devices-Based System Designed to Improve the Treatment Adherence of Hypertensive Patients

“…Many groups are searching for precise methods to measure the actual BP of patients in diverse types of treatment. It is known that body position can affect the values obtained, and techniques were developed to overcome the related effects [55,56,57]. When dealing with clinical situations, the cardiovascular control conditions and the automatic measurement of BP may be crucial and demands more precise and even invasive devices [58,59].…”

Technology and Properties of Peripheral Laser-Welded Micro-Joints

“…− Micro-welding of materials with diverse properties [2][3][4][5][6][7]; − Choice of laser type and the impact of the operating parameters on the joint properties [1,[7][8][9]; − Micro-welding of materials with diverse shapes and sizes [2][3][4]; − Modelling of the micro-welding process [1,[10][11][12][13][14]; − Evaluation of properties and metallurgical changes of laser-welded micro-joints [15][16][17].…”

“…Here, we are dealing with a material with a very low heat capacity, and therefore the energy supplied must be extremely precisely selected. Laser welding technology, as opposed to standard methods, is distinguished by features that make laser welding, on a micro-scale, the best possible solution next to electron-beam welding [3,4,9]. This is determined by the possibility of choosing the type of laser beam used for welding, the possibility of precise energy dosing in the form of pulses of a short duration and the possibility of focusing the beam on a very small area located in a specific place.…”

“…Nd:YAG, fibre and disc lasers are the most commonly used lasers for micro-welding applications [1,[18][19][20][21]. The current research interest is focused on the use of ultrashort pulse lasers [6,9]. The nanosecond and picosecond interaction of pulses causes a qualitative change in the phenomena occurring in the material and is a rewarding research area, which also enters the field of micro-welding.…”