FlexiForce FSR Sensor can help you to measure the force between almost any two surfaces. The sensors are highly flexible, have a paper-thin construction and robustness to stand up to most environments. Tekscan, the manufacturers, can create custom-designed force sensors because of the high durability and unique construction of the basic FSR sensor element. These meet the specific needs of several OEM customers. Off-the-shelf standard sensor products are also available for low-quantity requirements such as prototyping.

With FlexiForce FSR sensors, you can detect and measure any relative change in the applied load or force, the rate of change in force, detect touch and/or contact and identify force thresholds to trigger appropriate actions. Using a FlexiForce OEM force sensor offers several advantages over a competing product, such as superior linearity and accuracy of +/-3% over a wider range of forces. Tekscan provides expert technical guidance in custom solutions and they test all custom sensors to ensure they meet the agreed-upon specifications. Typically, the sensor output is not a function of the loading area and high temperature versions are available as well, going up to 400°F.

The FlexiForce FSR sensor functions as a force-sensing resistor within an electrical circuit. When there is no load or the force is very low, the resistance of the sensor is very high. The resistance decreases as force is applied to the sensor. If you connect a multi-meter to the outer two pins of the sensor, you can read a resistance, which will change when you apply a force to the sensing area. The sensor allows measurement of force against either resistance or conductance. Since the conductance curve for the sensor is linear, calibration is simple.

Integrating a FlexiForce FSR sensor within an application is very easy. One way is to use it in a force-to-voltage circuit. It will be necessary to calibrate the sensor for converting its output into the appropriate engineering unit. Based on the setup, you can easily adjust the arrangement to increase or decrease the sensitivity of the force sensor.

Typical performance specifications of the sensor are very impressive. The error in linearity is less than +/-3%, when the line is drawn from zero to 50% loading. When applying 80% of full force, a conditioned sensor can be expected to be repeatable with a spread of less than +/-2.5% of full scale and a hysteresis of less than 4.5% of full scale. With a constant load of 90% of the sensor rating, the total drift does not go beyond 5% per logarithmic time. If you are measuring impact load, the time required for the sensor to respond to an input force is less than five uS. The sensors work reliably between 15 and 140°F or -9 and +60°C, which are standard. For High-Temp versions, the operating range is 15 to 400°F or -9 to +204°C. The force reading change per degree of temperature is +/-0.2% for every °F or 0.36% for every °C.

FlexiForce FSR sensors have a variety of applications. They are used in bed monitoring, color balancer quality control, fitness training, golf grip measurements, improving robot balance and grip, detection of infusion pump occlusion and several other manufacturing and monitoring purposes.

Today, almost all of us use mobile phones every day and we depend on them for many features that personal computers offered earlier. The major advantages of mobile phones is their mobility, compact form-factor, always networked and untethered to power (except when charging). Moreover, mobile phones are now platforms that support continuous sensing applications.

Although mobile phones nowadays house many sensors such as imagers, gyroscopes and accelerometers, some sensors such as soil moisture, air quality and EKG have not been integrated yet. Many people desire support for such sensors and prefer a limited set of direct-connecting interfaces that make it suitable to power external peripherals for transferring data to and from them. This has resulted into a search for a universal peripheral interface port.

Every mobile phone has a headset port, which is almost standardized. Users can connect physically and electrically a vast range of hands-free and headphone audio devices. Therefore, the mobile phone’s headset port is a suitable candidate for such a peripheral interface. Recently introduced peripherals show that designers and manufacturers have a growing interest in using the mobile phone’s headset port for more than just headsets.

Transferring power and data to peripheral devices via the headset port looks an attractive proposition when considering the cost, simplicity and the ubiquity involved in the process. However, different mobile phones show considerable variance in their power delivery ability, microphone bias voltage and passband characteristics among their headset ports.

Therefore, contrary to recent claims, one is forced to conclude that the headset port is not as universal as it is made out to be. For example, peripherals designed to work with iPhones may fail on other Windows or Android phones and vice versa. Moreover, designs for smartphones may not be suitable for less capable feature phones. Therefore, mobile phone peripherals may have a hard time working with the headset ports of different mobile phones.

A new platform, called the AudioDAQ, makes it easier to acquire data continually via the headset port of a mobile phone. Unlike existing phone peripheral interfaces such as HiJack, AudioDAQ draws all the necessary power from the bias voltage of the microphone. It encodes all data as analog audio while taking advantage of the voice-memo application built into the phone for continuously collecting data.

Therefore, AudioDAQ is not limited only to iOS devices, but works smoothly on smartphones and feature phones as well – no hardware modification is required on the phone. Compared to HiJack, AudioDAQ has extended sampling periods, which is a result of using a power-efficient analog solution, making it suitable for a large class of sensing applications.

The efficient AudioDAQ design draws all its necessary power from the microphone bias voltage. Since this voltage is present on all phones, irrespective of whether it is a smartphone, feature phone, Android or iOS phone. Moreover, the voice memo application is present in almost all mobile phones. That makes AudioDAQ almost universal in its application. Designers of AudioDAQ have demonstrated the viability of their architecture by and end-to-end system that captures EKG signals continuously for several hours and sends the collected data to a cloud for storage, further processing and visualization.

We hear so much of 3D today that we are no longer surprised with 3D printing, 3D movies, 3D gaming consoles, 3D TV sets etc. Therefore, 3D tablets ought not to come as a surprise. When we live in a 3D environment, it is no wonder that we try to capture it in 3D. Therefore, very soon we will have 3D mobile devices that will not only display 3D movies and games, but also record videos and pictures in full 3D.

In the past three weeks, Google set the whole news world abuzz by announcing their Project Tango and you can see them working with NASA here. The goal of the Project Tango is to let a mobile device sense space and movement in a way similar to what humans do. Google released their first prototype in February 2014 – an Android smartphone with a five-inch screen. The smartphone uses special software for tracking the movements of the device entirely in 3D motion. Measuring over 250-thousand 3D movements every second, it creates a virtual space model of the user’s environment.

Wall Street Journal reports that Google is on its way to building a first-generation 3D tablet as a part of the Project Tango. According to the report, apart from the usual sensors that are present on current tablets, the 3D tablet will have additional and advanced vision sensors such as sophisticated 3D cameras and infrared depth sensors including dedicated software.

The report suggests that Google may well be producing about 4,000 such units of seven-inch tablets for presenting at their annual developer’s conference. Possibilities are the tablet could have the ability to create accurate virtual worlds from real-world environments. This would be similar to mockup sets, and would be of great assistance to movie producers and game developers, as it could cut down on digitizing time.

The report also conjectures that the Movidius Vision Processor, also known as Myriad 1, would power the new tablet – this can map space and motion in real time and with detailed accuracy and precision. Myriad 1 is specifically designed to handle these tasks, and Movidius has a set of tools for developers planning to implement 3D solutions quickly.

Very soon, users will be able to experience the new way of how a mobile device can be used to experience the world and Google is paving the future direction that smart mobile vision systems are expected to take.

Although 3D technology is nothing new, the potential of commercialization by a company such as Google, at an affordable price, is the transforming point in its adoption. As such, phones and consumer tablets running on the Android Operating System are already highly popular. Google, by developing this really compelling technology, is helping fields such as medicine, real estate, engineering and automotive, which make heavy use of video and imaging.

As many of these fields already make extensive use of imaging technology, the next stage will open up huge vistas for them. Imagine doctors and researchers able to see and understand human health in an entirely new way. Other uses can be very diverse such as a property inspection by a prospective buyer or examination of a road project.

Where precision resistors are concerned, a small size may not always be the perfect answer and SMT has its trade-offs. Power density in surface-mount chip resistors is higher than in through-hole parts, which results in chip resistors running hotter. Surface area in the case of through-hole resistors is higher, allowing them to dissipate internal heat to the surrounding air, while SMT devices mostly dissipate through the PCB. That leads to heat build-up in the system, affecting all the components. Due to this excess heat, long-term stability of resistors is degraded, especially when operating at higher temperatures.

Configuration considerations also affect SMT components. The length vs. width of the chip is an important parameter. If this aspect ratio is beyond a limit prescribed by reliability studies, generally ~2:1, board flex stresses may cause the chip to de-laminate from the board or to crack. Widening the chip does not help to eliminate the stress – rather that makes it harder to remove solvents and resins from under the chip.

Therefore, the best choice of a resistor for high-precision application would be one specifically designed to provide higher resistance value, dissipate higher power, be available in tighter tolerances and provide better long-term stability. It must also use less board space and allow easier cleaning of resins and solvents. All this is possible when precision resistors are configured in metal hermetic cans or in molded rectangular blocks, with through-hole leads extending from the bottom surface. The construction also prevents the resistor from being subject to thermo-mechanic stresses from the PCB.

Such constructions, which include stand-offs, allow reliable cleaning from under the component and the approach also minimizes the required board space. However, on some occasions, the only option available for design is to use an SMT. In such cases, using a surface-mount device with flexible terminations will be most useful.

The main idea behind use of SMTs is miniaturization. However, a tightly packed board may not always be a good idea, specifically for precision applications. For example, a mounted resistive element placed parallel to the PCB is susceptible to vibrational movement, resulting in parasitic microphonic noise. This is one reason designers do not prefer using SMT components in the feedback path of circuits. A better choice here would be to use vertically oriented through-hole parts. The legs help to absorb the deflections from the PCB.

For a precision resistor to remain stable over long periods, its temperature must remain within limits specified by the manufacturer. Heat from adjacent components and changes in the ambient temperatures affect the stability. This is defined by the TCR or temperature coefficient of resistance. Self-heating (because of load), is another factor and this is defined by the Power TCR or power coefficient of resistance.

Specific equipment such as medical instrumentation using precision resistors is highly dependent on these performance characteristics. Designers prefer to use Bulk Metal Foil resistors to deliver proven stability and reliability performance. Bulk Metal Foil resistors perform superbly even when exposed to unstable levels of humidity and temperature including other harsh environmental conditions. Foil resistors also feature non-capacitive and non-inductive designs.