Touch Free Operation for Smartphones and Other Handheld Devices

Technology #d-1126

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Changzhi Li, Ph.D.
Dr. Li's research interests include doppler radar for biomedical and structural health monitoring, CMOS RF and analog circuits, and microwave circuits
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Chenhui Liu
Changzhan Gu
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Cameron Smith
Licensing Associate 806-834-6822
Patent Protection

Provisional Patent Application Filed

PCT Patent Application Filed
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Non-contact_Hand_Interaction_with_Smart_Phones_Using_the_Wireless_Power_Transfer_Features.pdf [PDF]


Touchscreens are appearing in more and more products and used for controlling the operation of the devices.  This is especially true as it relates to smartphones.  There is currently no method for the operation of smartphones without some form of physical contact with the phone. Since wireless charging is now a standard feature for many smart phones, a system that leverages the wireless charging coil, can also enable a sensing system that will allow for touch free operation of the device.

Smartphone technology utilizes resonant frequency from the wireless power transfer (WPT) coils and a Colpitt’s oscillator to enable the non-contact interaction. The resonant frequency of the WPT coils is influenced by the interaction of a user’s hand. By analyzing how this frequency changes, it is possible to sense the hand movement of a user.  This technology is already available using the existing charging coil, so very little additional hardware is needed to incorporate this feature into the phone. Potentially, it may also prove to be more power efficient than existing touchscreen devices with remote recharging capabilities.

Reference Number: D-1126 

Market Applications:

  • Smart phones
  • Hand held health care devices
  • Scanning devices

Features, Benefits & Advantages: 

  • Ability to control a smartphone without touching the screen 

Intellectual Property: 

  • A U.S Provisional Patent Application, serial 62/106,318 was filed on 01/22/15, and a PCT application, PCT/US16/14592 was filed 01/22/16.

Development Stage:

  • The inventors have built and tested a prototype. The next step is to design the whole system into an integrated chip. 


  • Chenhui Liu, Graduate Student, Electrical and Computer Engineering, TTU
  • Changzhi Li, Ph.D, Assistant Professor, Electrical and Computer Engineering, TTU
  • Changzhan Gu, Senior Hardware Engineer, Marvell Semiconductor Inc., 994 Helen Ave Apt 3, Sunnyvale, CA 94086. 


Keywords: Hovering touch screen, Non-contact touch screen control, No touch smartphone interaction, Colpitts oscillator, Spectogram